Replacing a gas boiler with a heat pump 

Bob, Good Evening. You probably can't tell but I'm blushing. Thank you for your kind words. Drop me a line if you have any questions: M

@@michaeldepodesta001 I will definitely follow up. Just set my gas boiler to always on at 40 degrees as a test. I h e never seen that recommended before. I have a DHW tank so will boost with immersion overnight, I am on Octopus Agile and rates low tonight

Dear @fje1948, Thank you for your kind words. And good luck with your heat pump installation. Do drop me a line if you have any questions. Best wishes. M

Phil, Good Morning. Thank you so much for your comment which actually made me cry. I am happy you found the video helpful and I wish you all the best in your future endeavours. M

Paul O'Donnell, Good Evening, please forgive my delay in replying. I'm afraid I don't know your circumstances, either financial, geographical or structural. So here are some comments which may or may not be helpful. First of all, Air-Water heat pumps systems are well established in Europe and they have SCOPs that are more or less as good as ground source systems - but with much less hassle. I recently wrote about the 5 things that go wrong with installations in the UK - you might find that helpful. protonsforbreakfast.wordpress.com/2024/02/10/5-reasons-heat-pump-installations-have-problems/ They are very reliable in operation - but nothing is perfect, and I would encourage to employ a system that can be serviced - without relying on expensive imported parts. Second, *in principle* air to air system ought to have a high SCOP. Why? because the pitied evaporator technology is similar, but the heat exchanger between the working fluid and air should be more efficient and allow for lower temperatures of the working fluid. e.g. it you need to reach 20 °C internally, you need only heat the working fluid to (say) 25 °C to obtain good heat transfer you your dwelling. Using water in radiators you may need to heat water to (say) 35 °C to obtain teh same heat transfer. One downside of air-to-air systems - is that they don't meter themselves! And so it can be impossible to know how efficient your installation actually is! Finally, getting to net zero is tough. But stopping burning stuff is the key - which ever system you go for (and I recommend low GWP refrigerants whatever you do) will be dramatically better than burning gas. For me, Our emissions have fallen from about 4.5 tonnes/year to about 0.7 tonnes. I've also bought a fraction of a wind farm via Ripple and I pay Climeworks to physically bury 50 kgCO2/month. I'm working on my diet habits now and am foresworn from flying. I wish you good luck in your endeavours - and I hope you can stay joyful and positive in these difficult times. Best wishes M

Thanks for comprehensive reply. Again, very helpful!

John, Good Luck. Do ask if you have any specific queries. All the best: M

Steve, Good afternoon. I'm afraid I can't answer specifically to your system, but in general using Weather Compensation (WC) will give you the most comfortable home at the lowest cost. In my own system (Vaillant heat pump) I use WC with an 'extended' setting. Vaillant don't specify exactly how this works but I think it uses WC, but if it has difficulty achieving the target temperature it adjust the output slightly (I think it adjust the slope of the WC curve) based on the thermostat setting. You can see an example of the performance below. protonsforbreakfast.files.wordpress.com/2024/02/heat-pump-errors-10.png Solar gain is difficult for all control systems, and I am not sure that PURE-WC or PURE-THERMOSTAT will give you the best answer, but a sort of hybrid mode might sort of allow you to muddle through. If you start to play with the settings I encourage you to write down everything you do - and maybe take a photo of the setting in the App or Controller - it's very easy to get completely lost! Best wishes M

@@michaeldepodesta001 Thank you Michael. I won’t be tinkering with the settings without professional help! I have a Heat Geek engineer coming to service the boiler so I’m hoping to get better advice than I did from the installer. Thank you again for taking the time to reply. Any new videos in the pipeline? They are always a great watch.

Ian, thank you for your kind words: M

Keith: Thanks for your kind words: and good luck with your project. It's all still much harder than it should be! M

Tom: You're welcome: Thanks for taking the time to stop by. M

Paul, Thank you for your kind words. M

@frederickbowdler8169, Good Evening, Thank you for your kind words. Do drop me a line if you have any specific questions. Best wishes Michael

Hazmat: Great News. My top tip is to read your gas meter each week this winter so you can record how much gas you are using to keep your home at the temperature you want it. This will be helpful in choosing the correct heat pump size. Good luck!

@@michaeldepodesta001 I have monthly gas readings going back 3 years and use on average 12800 Kwh per year (for both heating and hot water at 80% boiler efficiency). In Jan-Feb I use on average about 70 Kwh per day. Incidentally my 35 year old boiler runs at a flow temperature of 52.5 degrees, very strange, but it seems to do the job.

@@hazmat5749 Sounds you are heat pump ready! Good luck with endeavours. M

Robert & Zandra: Thank you for your kind words: good luck with your endeavours! M

If you will have to wait for at least winter, then prepare by reading your gas meter once a week. You can then put the results in a spreadsheet and see what your real heating requirement is: this should help you get the right size heat pump when the opportunity occurs.

Charlie: I hope it all goes well for you. Best wishes: M

Arwin: Thank you for your kind words. And goof luck with your endeavours. M

Sorry, I mistyped your name: Apologies. M

Rob, thank you for your kind words. 1. If you have a 4 kW(peak) array in the UK then depending on orientation I guess you will generate between 3,000 kWh and 4,000 kWh/year. In summer peak generation will be ~25 kWh/day and in winter it will typically be ~2 kWh/day. 2. My house required 3.5 kW of heating when it was - 5 °C last week and this was supplied with a COP of about 2.5 - so it required 3.5/2.5 ~1.4 kW of electrical power. Over 18 hours this amounts to 1.4 kW x 18 hours = 25 kWh of electricity. Our battery is a Tesla Powerwall 2 with 13.5 kW nominal capacity. Currently capacity is about 12.2 kWh (protonsforbreakfast.wordpress.com/2023/12/30/solar-pv-review-of-2023/). 3. We charge up the battery on cheap rate electricity from 11:30 p.m. to 5:30 a.m. and then run off the battery until it runs out. On the cold days with no Sun, we ran out of battery in early afternoon. With bright winter sunshine we managed to make it through to 4 p.m. or so before running out. Regarding heat pump sizing, do make sure that your gas consumption corresponds to a situation where you are keeping your home at a reasonably constant temperature during the day. If you are switching off your gas for half the day, and the house cools, then using the rule of thumb this will lead to an underestimate of the size o heat pump required. Drop me a line (house@depodesta.net) if you need any clarification. Best wishes M

@@michaeldepodesta001 Hi Micheal, thanks ever so much for the helpful response. Lots of food for thought. You've accurately surmised by solar systems generating capacity so it's helpful to know that Vs what your heat pump requires. Following your message, I've also tweaked how we are heating our house to a constant setting (we were previously heating intermittently) to get a better idea on demand and sizing. Thanks again, I really appreciate you taking the time to write. Cheers Rob

Leslie, Good Evening. Excellent! If you have any collective questions, please do feel free to drop me a line either here or at house@depodesta.net All the best Michael

Good Morning. If I understand correctly, in a condensing boiler then the water vapour in the combustion exhaust is condensed by having the inlet cold water pipe flow around the exhaust. This condenses the water vapour, releases extra heat and the condensation is captured and dripped away outside. In a non-condensing boiler, the hot exhaust gas flow straight out of the house. So I don't think lowering the flow temperature could cause condensation. Lowering the flow temperature bit by bit is a smart way to (a) reduce bills now and (b) see if your system is heat pump ready. Obviously the best test is on a cold day. The article below summarises my heat pump performance over the last three years. In my installation, the evidence shows that the low-loss header did not make a difference: it was unnecessary. But neither did it seem to do any harm! Plumbers explain this badly, but roughly speaking, if an installer does not know what the radiator pipework is like, then installing a low-loss header is like an insurance policy: It makes sure that the installation will work - but it may not be optimally efficient. protonsforbreakfast.wordpress.com/2024/08/21/2024-summer-summary/ I think low loss headers and buffers are different. I think a buffer adds some water volume to the system to prevent the heat pump cycling on and off too quickly. I think a low loss header is used to match the flow impedance of the radiator network to the hydraulic pumping power of the heat pump. Do get back to me if this isn't clear. And good luck with your endeavours! Do visit some owners (or me! I'm in Teddington) to see how they feel about it app.visitaheatpump.com Best wishes M

@@michaeldepodesta001 Thanks for your reply, and a very good video btw. Its widely said across the Internet that you should avoid flow temps below the dew temp in a non condensing boiler as it will allow condensation that will cause corrosion of the boiler (and I presume a water leak as there is no means to capture the condensate). I was challenging that to see if it mattered for a just couple of days or so. Otherwise I would have done it years ago 😉 I would do the test when its colder. I thought a volumizer adds water to the system (to aid defrost for example) but a buffer reduces cycling when the flow rate isn't high enough to exact the heat (e.g. with some microbore). This sounds like what you are describing as a low loss header, so maybe there are the same? Btw, love physics, especially "spooky action at a distance"! Life relies on it, e.g. neurons simultaneously firing 👍And nuclear fusion is still "only 20 years away" 😄

@montyoomska, Good Evening, Mmmm. Tricky. First of all, I can't give you a definitive answer, but here are some reflections. 1. Boilers do last a long time - frequently for decades. But when they break, I have never heard of a boiler breaking from 'being on too much". What breaks are nearly always electromechanical components such as electric valves, relays and pumps. 2. If a boiler has an output power of (say) 20 kW which it can modulate down to 5 kW, then components in the primary heat exchanger (which extracts the heat from the flame) will get less hot, and will not heat up and cool down so frequently. I would imagine that would lead to less stress and less corrosion. So my guess is that modulating a boiler to lower output is generally beneficial rather than harmful. 3. Improving efficiency by 10% is (neglecting standing charges) 10% off your gas bill. If that's £1000 a year, then that's £100/year. Have I missed something obvious? All the best Michael

Darren, Good Afternoon. I wrote an article about this issue here: protonsforbreakfast.wordpress.com/2023/08/02/hydronics/ Hydronics is the fancy name for plumbing. Heat pumps are good at producing heat, but they need to circulate a lot of water to pass on that heat. Narrow tubing requires a high pressure to pump the water through. As the article says, the standard approach to this is to use what's called a low-loss header to help the heat pump circulate water, and then to use an auxiliary pump to push the hot water through your radiators. I have chatted with people on Twitter who have heat pumps micropore pipes and are happy with their installation, but without seeing, I can't say for sure if it is achievable in your home. The issue about flow temperature is not associated with micropore pipes but wit radiator area. If you have large multi panel radiators AND you can get enough water to them - then you can have a low temperature installation. Octopus tend to avoid 'difficult installs' and I recommend you search for a HeatGeek-trained installer who will be your best chance to get a good installation. And other heat pumps - such as the Vaillant Arotherm plus series - can heat to 70 °C too. Good luck - it's a stressful activity! Do ask more detailed questions as you progress. M

Colin. Thank you for your kind words. Insulating your loft is definitely to be recommended. I would suggest you read your gas meter weekly for the rest of the winter and perhaps for next winter. This will allow you to save up your money and assess your real heat loss. protonsforbreakfast.wordpress.com/2022/11/07/what-to-do-on-the-coldest-day-of-the-year/ ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-hCeghKa3liM.html Best wishes Michael

Kevin, thank you for your kind words. And yes, I agree with you. If you have the capital available, then the combination of Solar PV, a battery and heat pump works very well together to reduce teh running costs. For example at the moment with this very cold weather, half my electricity is cheap rate. For most of the winter it's more like 80% cheap rate. Together with a COP of 3 this makes the heating very cheap. Good luck with your endeavours! Michael

@@michaeldepodesta001 Whilst the £5k grant and the VAT exclusion are welcome there aren't going to be enough consumers with a spare £8k to make the switch. A favourable government loan to cover the shortfall would probably make quite a difference on the level of uptake. Just like we have the Student Loan Company, we could have the Carbon Reduction Loan Company.

@@bvqbvq , good evening. I think they use a loan scheme in Scotland, although I do not know the details. But yes, I think that would be a great idea. All the best: Michael

Mohamed, Good Morning, Firstly let me answer your question: The battery I have is a Tesla Powerwall with 13.5 kWh of storage. Since November 2019 I have had 12 x 340 watt peak panels: 6 facing 20° E of South and 6 facing 20 ° S of West. But in November this year I added more panels. I added 3 x 390 watt peak panels on a flat roof and 5 on the main roof facing 20° N or East. I discuss the installation and my expectations in this blog article protonsforbreakfast.wordpress.com/2022/10/27/new-solar-panels/ Now let me tell you what I *think* is the right way to get a balanced system. My wife and I use around 10 kWh/day of electricity - excluding heating. If the children were still with us this might be as much as 20 kWh/day. This consumption sets the scale of the storage you require. I think optimally - balancing cost and utility - one should aim for battery storage to cover about one day's household consumption. Batteries are expensive but they can generally be installed in slowly over a few years. Regarding solar, I would recommend to get as much as you can. The panels themselves are cheap and while the people are on the roof it doesn't take much time to add another panel or two. I expect annual yield to go up from around 3,800 kWh/year to around 6,000 kWh/year. But the key result is how many kWh/day of solar one gets. For our current system in summer we get ~15 kWh/day on average and in winter ~ 3 kWh/day. This should be compared to 10 kWh/day summer consumption. and 25 kWh/day winter consumption (including all heating) So in summer we get ~ 15 kWh/solar which runs the house and charges the 13.5 kWh battery and we then run on the battery overnight. In winter we buy 130.5 kWh of cheap electricity at night and then run on the battery for most of the day, generally running out late in the day. Solar tops up the battery a tiny amount during teh day. Check out the website and use the search function for more articles. protonsforbreakfast.wordpress.com Good luck with all your endeavours. M

@@michaeldepodesta001 Many thanks Michael for this detailed reply which is very useful for me. I have already a 6kwh solar (16 x 380w panels facing south) and no room really to add more. I have also 19kwh battery (pylontech). Now I am thinking about the heat pump and was worried about the cost especially that my combi boiler is new (two years old) and my annual gas consumption is low (8000kwh max). I am very surprised that you meed 130kwh every night during winter. That’s really a lot. What is the size of your heat pump? Octopus just finished their report and they are suggesting 8kw pump and just two radiators to change. Thanks again for caring.

@@DahouiM Firstly 6 kW-peak is a great installation and 19 kWh of batteries is LOADS! If your gas consumption is 8000 kwh then I can't see any way that you can possibly need an 8kW heat pump. It's almost physically impossible. What to do? If we have any more cold weather this winter (i.e. around 0 °C) try measuring your gas consumption (in kWh) in the coldest weather over 24 hours. If you divide by 24 your will get a pretty solid estimate of your heat pump size. Having an oversize heat pump is not a disaster - it's very very common - but it costs more and won't get teh best COP. I don't use 130 kWh each winter night. This graph shows the daily consumption (average power) versus external temperature during the cold weather. protonsforbreakfast.files.wordpress.com/2022/12/cold-weather-2.png Peak heat demand is about 3 kW(i.e. 72 kWh/day) with -3 °C outside which we meet with around 30 kWh of electricity consumption (COP = 2.5) This is easily met with the 5 kW heat pump. Indeed, we could get by with one size down. Over most of the cold winter we use around 45 kWh heat a day - with a COP of between 3 and 4. Good luck. M

@@michaeldepodesta001 many thanks Michael for all the help and willingness to provide all these details. I will now consider my options seriously. 8kwh pump is what Octupus are suggesting and I don’t think they will change their mind to ensure their installs meet their requirements. It still worries me that the heat pump would consume more than 30kwh a day

@@DahouiM 30 kWh/day of electricity is just 1.25 kW on average. That's not much to heat an entire house! Of course teh thermal power would be around 5 kW.

Mohamed, Hi. Good Evening, First of all, congratulations: you are now savings TONNES of CO2 emissions per year! Secondly, yes, assuming you are in the UK as I am, with outside temperatures above 10 °C your radiators will be barely warm. As I type, the outside temperature is 10 °C, the radiators are at about 30 °C, and the room temperature is 20 °C within ±0.5°C. The COP is about 4.3. In my house the maximum radiator temperature is about 45 °C when the outside temperature is -3 °C or so. I think after a while you will get used to it - it's weather compensation in action. My guess is that we will still have a cold spell or two to come before spring and summer finally arrives and then you should see the radiator temperature rise. What you should never be is ...cold! Best wishes: Michael

@@michaeldepodesta001 thank you so much Michael. Yes I have the same conditions as you (by the way I am in the south east as well). The weather compensation is active. All the best

Great: I hope everything goes well. BTW, (and I don't know if this is relevant) but over the summer I switch my hot water cycles from night time (using cheap electricity) to daytime (using solar electricity - and since the air is warmer during the day it is more efficient). Best wishes: M

@@michaeldepodesta001 many thanks Michael, yes it’s a learning curve. You are a scientist with experience in measurement and clearly the sensors in the house are indicating the desirable temperature but somehow our body feels the warmth when it comes as bursts of heat instead of gentle heat.

@@DahouiM I am concerned that you might be cold! If you are cold, you need to increase the setting on the thermostat, change the weather compensation setting or put on a pullover! A thermometer can tell you the temperature, but it can't tell you whether or not you feel cold!

Dear 'The Askews' Firstly I would encourage you to make the change if you can, but don't beat yourself up! Secondly, Tom Swaffield-Bray (@tom_bray on Twitter) lives in teh NE and has just installed a heat pump. He may have knowledge of suppliers in your region, or use the Heatgeek web site. 11 kW and 14 kW are big heat pumps and based on your description of your house it sounds a lot, but maybe your house is detached (lots of outside walls) and in a windy place. What was your gas usage last year? Also, if you don't install this year. Be sure to read your gas meter once a week to get a real sense of how your gas demand varies. This will be really helpful for sizing the heat pump. Best wishes Michael

don't undersize it will burn money and never heat the house properly

@@richardbartlett6932 Hi. Obviously one would aim to get the 'right size' every time. But a little undersizing is probably not that harmful. Why do I say that? Well a modestly undersized heat pump will heat a dwelling well for most of the heating season when the heating demand is below the maximum. On the coldest days, additional electric heat will be required. This will come with a COP of 1 but it is not worst case. And oversizing by a factor two or more - which is common - is not without it's problems such as a extra cost and inefficient use of the pump during most of the heating season. Obviously, 'the right size' is the right choice, but undersizing is not a disaster and can be a reasonable choice. Best wishes Michael

What was the lowest flow temperature you could achieve with 6kW of heat delivery? That's an important data point in figuring out how your house works! M

I had a similar issue with traditional electric water heater (simple thermostat controlled ) as opposed to heat pump. My fault being I did'nt even bother to check the power termination on the cylinder before I replaced it. We have an off peak for the water heater. I've tracked the consumption and it averaged 13-14 kWh/day. After I had it replaced, I thought I should as least have a look at the temperature adjustment knob on the outside. Well, bugger, not that the knob actually did anything !! It just appears to be a cover with a knob that must have been designed for another under cover control for the same unit. All that was in there was an inline resistor and thermostat with a temperature control similar to the pre-set potentiometer type. And the previous owner had set it to max temp of 70 C. So far the heat pump is going well though. The long term results are still in the making but tracking overnight 24 hour consumption over the last two days, it's already down by 5 kWh. And we are still in early spring here.

@@greywolf271 It seems that every installation is an adventure! Good luck!

@@michaeldepodesta001 how do you find this out? I’ve lowered my flow to 50 for now but as not every room is calling for heat its still cycling. Will be trying to heat the entire house to see if that helps - but I can’t see the energy consumed by the boiler. I’ve done rough numbers done and someone look at the radiators and I appear to be heat pump ready (even the ‘low hanging fruit’ that Octopus prefers). Main caveat to me is hot water - don’t really have convenient room for a tank anymore, so would prefer something like a sunamp but that massively increases the cost. Same if we had an electric boiler. a combi-style instantaenous but centralised hot water system would be good for users like us - COP for HW is low anyway

​@@MrKlawUK Hi. The only way to get a handle on gas consumption is to read the meter regularly. I read all the meters once a week, and the gas meter reading corresponded closely with the outside temperature. If you change the boiler flow temperature you should see a change in that correlation. Regarding DHW, in the video at 49m11s there is a picture of an installation of an outside insulated 'hutch' for a Sunamp unit. Might something like that be possible? DHW COP is not bad - above 3 at this time of year protonsforbreakfast.wordpress.com/2021/09/07/assessment-of-heat-pump-heating-water-to-50-c-and-70-c/ which is a factor 3 reduction in cost and carbon. It sounds to me like you are on top of most of the important issues. Congratulations. M

Thank you for your kind words. :-)

Thank you: Not a tiny error - a factor 10! I did flag the error and would edit the video if I could -. Sorry. M

Thank you for your kind words. protonsforbreakfast.wordpress.com/2023/03/27/the-gas-man-cometh-for-the-last-time/ My wife asked to keep the gas supply for the winter of 2022/23 in case of Power Cuts arising from the Ukraine crisis. The gas meter is gone now. All the best Michael

Adrian, Good Morning. When we had our system installed it was with a low-loss header - which functions similarly to a buffer. At the time I did not really understand why and wrote this article about the role of a low-loss header to try to explain it to myself. protonsforbreakfast.wordpress.com/2021/06/10/heat-pumps1/ I think buffers and low-loss headers improve the chance that a system will "work" first time. But I am pretty sure it reduces the best achievable COP. We have had the system for two heating seasons now - I'll be comparing the two seasons on my blog sometime in July - and achieved a COP of 3.5 for both years. This is good, but I am considering having the low-loss header removed to see if that improves the COP for the next heating season. Advice? It's difficult to advise you remotely, and in the end you are in the hands of your installer. Personally, I let the installer do what they thought best, and it has worked out OK for me. But you could ask the installer about why they recommend a buffer? And if you are prepared to take the consequences, insist on leaving the buffer out. The problem with this is that if something doesn't work then the installer may not want to take responsibility. I would always want to stay on good terms with your installer! I am sorry I can't be more specific. But best wishes with your installation. Michael

Thanks Michael. I will install the buffer, but additionally i will install a bypass valve, as well, so that I can go around it, if/when needed.

@@adrianbotos2819 That's a great idea. Will you install a monitoring system such as Open Energy Monitor?

@@michaeldepodesta001, i will add a monitoring system, hopefully upon the Ashp install. They are not the cheapest gadgets, but i know i will need them, eventually….

@PaulRansonArt, thanks for stopping by. Three points in response to your comments. Firstly, with regard to embodied carbon dioxide in the panels and heat pump, that 'debt' is paid back in a year or two. Here are my calculations from a year or two ago. protonsforbreakfast.files.wordpress.com/2022/01/image_2022-01-01_172251.png The figure is part of this article protonsforbreakfast.wordpress.com/2022/01/02/carbon-accounts-2021-looking-back-and-looking-ahead/ Secondly, financially a heat pump by itself is borderline 'profitable' i.e. it has a long 'payback' time. However in terms of reduction in carbon dioxide emissions the payback effect is dramatic - resulting in ~80% emissions reductions. In terms of capital outlay, for many homes the UK government's £7,500 grant makes a heat pump installation similar in cost to replacing a gas boiler. Finally. Metaphorically we have set our house on fire. Putting out the fire does not come at zero cost. Best wishes Michael

@@michaeldepodesta001 I absolutly agree with your comments. We as a planet have no option other than to adopt a greener way of living. Such a shame that energy companies saw the £2,500 additionally grant as a windfall for them. Yes, my quote for a heatpump was £3,659 in addition to the £5,000 grant. When I saw the additional boost to the grant I leapt for joy as my quote would be reduced to £1,159! Right ....... think again. The quote remained unchanged but they would have pocketed the extra money. How on earth is this going to encourage us to change. My total investment on a solar system, batteries, and an ASHP would be £17,000. Add an EV and we're up to £50,000. Keep on making great videos and lets pray the economy of scale makes a greener solution affordable for everyone.

@@PaulRansonArt Oh Dear: that sounds depressing and potentially rage-inducing! I wish it were not so. Please allow me to wish you good luck with your endeavours. Michael

Whoops. How embarrassing to make such a basic error! Thank you for pointing that out. But it's still a big area!

Hi: The maximum temperature that can be reached is determined by the working fluid inside the pump. My Arotherm plus use propane as a working fluid and will heat water to 70 °C without the use of an immersion heater. I think one or two others can do this too, but I believe most heat pumps top out at 55 °C. Wow: An 8 kW-peak system: that's very impressive and will probably generate around 8,000 kWh. I am just in the process of upgrading to a system which might reach 6,000 kWh, up from 3,800 kWh. Together with a 13.5 kWh battery I hope this will allow us to stay off grid for 6 months of the year. protonsforbreakfast.wordpress.com/2022/09/01/its-been-a-sunny-summer/ protonsforbreakfast.wordpress.com/2022/10/27/new-solar-panels/ Do you have plans for a battery? All the best Michael

I just went with however many panels would fit on my roof, it's east west facing so not really 8kw peak. Not installed yet so I'll see. PW2 later next year

@@ExplodingPiggy Sounds very sensible. All I can wish you is good luck!

"You suggest this figure should be under 100 or insulation likely is necessary for a heat pump to be feasible." Jon, Hi. Did I actually say that? If so I think I may have mis-spoken. What I think is that heat pumps can heat any home, but a heat loss of 100 kWh/m^2/year is indicative of whether there is more you could do with insulation. If, for whatever reason, you have insulated as much as you can, then a heat pump can be made to work. 11 kW is a large heat pump so presumably you have a large house? It is very difficult for me to give specific advice without knowledge of your specific situation, and if someone has looked at your property in detail and thinks that - with radiator upgrades - it would be OK, then I would trust their 'on the ground' judgement. Best wishes in your endeavours. Michael

@@michaeldepodesta001 Thanks Michael, I thought you might say that given everything else you've said. Good to know. No we don't have a large house (although everything is relative) and I have challenged them (British Gas) on the size they are recommending but they have said it is down to the flat roof and large window on the extension and the chimney in our living room. Octopus wouldn't proceed after they surveyed as they felt everything was borderline (still 10-11kW) although they didn't suggest hardly any changes to radiators so I think they just have a different business model - choosing to install in homes requiring less updates of existing system perhaps as that way they can give lower fixed quotes. There is an additional irritation that they seem to be using the EPC energy use estimates which are higher in my opinion than they should be as I put in 300mm of loft insulation last year which seems to have reduced gas consumption by about 400 kWh (to 20350 kWh compared to the 2 years before), not to mention the assumptions they use in terms of construction, but they don't use the energy usage as stated on my bills. Sorry Michael, all my frustrations. Just putting you in the picture and I don't expect advice. I have noticed that the correction you did on 24th March on the coldest day spreadsheet doesn't seem to be there - the gas cubic metres option is not included in the formula. All much appreciated and all the best. Jon

@@JonWalker-l9h What a frustrating time. Here are a couple of thoughts (assuming your home is in the UK south of Manchester). 1. I hope you have made a typo and that the loft insulation saved you 4,000 kWh/year (about 17% of your consumption) not 400 kWh ((about 2% of your consumption - and well within annual variability). 2. Using the 'Rule of Thumb', 20,350 kWh/year corresponds to around 7 kW heat pump size. If you previously used 24,000 kWh/year then the 'Rule of Thumb' would indicate around 8.3 kW peak heat pump power - which in terms of heat pump sizing is not very different from 10 kW. Physically they are both likely to be large twin-fan units. And given the conservatism of installers, I can see why they are suggesting 10 kW heat pumps. 3. The whole process is very frustrating and filled with uncertainty. Please allow me to send my best wishes with your endeavours. Best wishes Michael

@@michaeldepodesta001 Michael, thanks so much. It is great to have your input and I do appreciate your thoughts. I have challenged again based on the fact they estimate heat loss rather than using energy usage according to my bills but it's really only me wanting to maximise efficiency of operation. I just want to see what they say. Yes, it was a typo. 4000 kWh saved with loft insulation. Jon

Alan.Good Afternoon. The issue of 'setback' conditions is very hard to resolve definitively. I'm sure you understand the trade off between (a) saving gas by lowering the temperature for a few hours and (b) wasting gas by having to heat rapidly at the end of the setback period. The optimised balance depends on the length (hours) and depth (°C) of the setback compared to the rate at which your home loses energy. I would suggest you measure it. This cold weather is ideal for these measurements. To do that just read the meter 24 hours apart with the set up as you like it. And then try an alternative. You will probably need to repeat the test a couple of times to be confident in the results and to compensate for changes in outside temperature. Drop me a line if you want help to interpret the data. We have a small AC system which we use in summer to keep the bedroom and hall cool, but we find the 'coolth' does not spread well through the house. A so-called mini-split AC unit could provide an economical boost to winter heat (it's a heat pump!) and offer cooling in summer. Solar gain is a difficult topic to discuss without specific knowledge of room orientation, but solar is very powerful. In summer it's 1 kW per square meter directly and if a big fraction of that is making it into your home you can have the equivalent of a multi kilowatt heater! Anyway: Good luck with your heating - my advice is to get some measurements under your belt! All the best: M

@@michaeldepodesta001 many thanks, yes I will do some tests - weather on the turn but worth trying - I think I might start with extremes, ie 65c/low hours v 40c/24 hours and judge the outcomes re comfort and cost. cheers A

David Joelsen, thank you for your kind words. The solar installation is a standard 3.6 kW-peak installation of 12 x 340 W (nominal) panels - 6 on a south-facing roof and 6 on a west-facing roof. The battery is a Tesla Powerwall 2 and has a capacity of 13.5 kWh. I think the video below has all the details including costings and installation photos. protonsforbreakfast.wordpress.com/2022/02/04/reducing-carbon-dioxide-emissions-from-my-home-video-and-slides/ Incidentally in a couple of weeks I will add to the solar installation by putting panels on the east facing roof and a flat roof above the kitchen. These are non-optimal locations and orientations but I hope the combination will add enough to perhaps allow me to stay off-grid for a whole 6 months. I explain the rationale in this recent article. protonsforbreakfast.wordpress.com/2022/09/01/its-been-a-sunny-summer/ Best wishes Michael

Mark, Good Morning, I'm afraid I can't follow you calculation - I think you have switch kWh and kW somewhere. Can you tell me your annual gas consumption and the rough location of your dwelling? All the best Michael

David, Good Morning. Replacing a boiler with a heat pump always makes sense from a carbon emissions reduction perspective, but I agree, it only makes financial sense if you can get access to cheap electricity through a battery/solar system. Best wishes Michael

Gerry, good morning. 'Downloading to a battery' is just charging the battery from the mains. Most batteries will have a Battery Management System (BMS) that will allow you to do this either once or regularly at a fixed time. Is your battery 4 kW in power or 4 kWh (notice the h for hours) in capacity. 4 kW in power is quite big, but 4 kWh is quite small. Do you know how much electricity you use each day on average? M

​@@michaeldepodesta001 Michael you are a gentleman,I didn't expect a swift response. Not at all "teckie" sorry. I took a number of screenshots but do not know how to send. Anyway the battery is a 3.85 kWh with 12 P.V panels installed last year. Average 25 kWh per day consumption or with 9 generated. I also heat with gas boiler and looking at possibly Air to Water? Lat years costs - Electric €1,300 Gas €950.

@@JG-cj5gm Here is my summary You have a battery capacity of 3.85 kWh You use roughly 25 kWh/day of electricity. That seems like the usage for a small family. Is that correct? Otherwise that’s a lot of electricity for one person or even a couple! You have 12 solar panels that generate 9 kWh/day. Is that 9 kWh/day in October? What does a battery do? Even in October, there is a lot of solar PV to be had. But if solar does not match your usage instantaneously, and without a battery the electricity is lost to the grid. Even a small battery such as yours will enable you stay ‘off-grid’ for much of the daylight hours. If you get a bigger battery it is possible to stay off-grid for longer and longer and over the summer it’s possible to stay off-grid for a month or two with 12 solar panels - even with your high daily usage. I don’t know your circumstances but if you have the opportunity to buy electricity cheaply at night, check if your battery management system will allow you to store that cheap electricity and run of the battery overnight. And if you have spare cash that you don’t need for anything pressing, and you can buy electricity cheaply at night, then a larger battery could save you a significant amount of money. In any case: good luck with your endeavours. Michael

@@michaeldepodesta001 Morning Michael, I really appreciate your time and thank you. Re the 25kWh per day it is used by 4 adults in the main house and my son and his wife in a studio apartment, all on the one supply. The studio is all electric with a monitor and they pay us for their usage. October panels have produced 10 days @ 9 kWh, 10@ 15/16k and 10@ 3/4. So October figure's Cons 770kwh, Gen 245, Buy energy 560, Charge energy 87 and Grid 38 kWh. I am told I will soon receive a payment for grid. I'm going to hold out on extra battery for now and hope to add ATWH in new year. Thanks for everything. Regards Gerry

@@JG-cj5gm Good luck: it sound like you are pretty much on top of things.

Mark, Good Evening. In my house, my wife and I use around 10 kWh o electricity for all the usual nonsense. How much electricity a heat pump uses depends on how cold it is and how well insulated your house is! But he's an example for my house. For heating I used to use ~7,500 kWh of gas per year which heated my home with around 90% efficiency i.e. around 7,000 kWh of heat. With a heat pump I still need to deliver ~ 7,000 kWh/year of heat but now with an efficiency between 300% and 400% so the heat pump uses between 1,700 and 2,300 kWh/year of electrical power. On the very coldest days in December, the heat pump average power was just over 3kW of heating power i.e. it delivered 3 x 24 = 72 kWh of heat with an efficiency of ~280% i.e. I used around 26 kWh/day of electricity to run the heat pump. On these extra cold days, the 13.5 kWh battery was emptied just after midday. That's very much a worst case for my home. With more typical December and January weather the battery runs out late in the evening. The link below has more details. protonsforbreakfast.wordpress.com/2022/12/11/cold-weather-measurements-of-heat-transfer-coefficient/ All the best Michael

@@michaeldepodesta001 Thanks for those real life stats. My gripe with the 'green brigade' is this. If you have a battery system coupled with solar, from Nov to March, the only way the battery will be replenished is via cheap overnight electricity. This is the same for all these with EVs too. The only way this is possible is because of access to ridiculously cheap overnight electricity. If everybody did this, there would be no overnight cheap electricity as there would be no 'off-peak'. I'd hazard a guess to say that the current infrastructure (sub-stations, single phase supply, increasing use of domestic electricity) could probably support as little as possibly 10% of people adopting a life-style similar to yours. If any more did it, there would be outages because of blown fuses, burned out cables etc. Then off course there is the up-front cost. I've installed an 8.4kW array, three 5kW inverters and a 15kW (usable) lead acid battery bank, not because I wanted to, but because my duel fuel bills have risen 600% since September 2021, when my 'fixed contract' was 'null and voided' when they went bust, leaving Octopus to pick us up. I've no doubt that Octopus and all the energy companies are in some kind of Government collusion because I left Octopus three years ago when I found a cheaper company, only to be returned to them now with a massive price hike. The cost for my install, doing it myself is about £10,000. My estimated usage this year was between £3500- £4000. My install should see this diminish to about £1000 if I judiciously monitor the system. To change my heating to ASHP is going to cost at least another £5000 doing it myself and double if using an installer. Another reason for doing this however, is that if the public were stupid enough to swallow the idea of a PANDEMIC which was 99.97% survivable in order to get them to roll up the sleeves three times or more, then how much easier it's going to be when they turn the electricity off because of nasty Mr. Putin.

@@fredflintstone1428 Hi. There's a lot to unpack in your comments. You seem very unhappy despite the prospect of heating your home with 300%efficiency! That makes me happy! Regarding, the idea that the grid will 'max out' I disagree. In 2002 peak grid demand was around 46 GW. In 2004 it was close to 60 GW. So the basic capability to cope with increased consumption is there. And the use of batteries will actually only smooth consumption reducing peaks and (as you said) increasing consumption when lots of renewable supply is available. Will it be easy? No. But widespread electrification of everything is the only way I know to continue to live a relatively good life without emitting carbon dioxide. Best wishes Michael

Yes! In all three cases - with a flow temperature of 75 °C or 38 °C) the heat delivered to you home by the boiler is the same. But in order to deliver that heat at 75°C the boiler has to use 11% more gas.

Soumen, Thank you for your kind words. M

Dear Porcupine Pete, Good Morning. Sorry to hear about your electrical woes. As you say, if you don't have a reliable electrical supply, then a heat pump is not a good choice - at least not without a large battery. If you don't care about emissions of CO2, then a gas boiler is great. All the best Michael

Steve: Thank you for your kind words. Heat pumps can be mounted on walls and elevated. It's a good solution if you have a side wall to your house. If you are totally stymied - and the regulations are mad - then consider an air-to-air system. AKA Air conditioning. These systems can heat as well as cool and have a very high COP for heating air. In a multi split system, 1 outdoor unit can supply 4 or 5 indoor fan coil units that are mounted above doors. If you have a large home you may need to 2 systems. Pros are that they are very efficient and you get summer cooling for free! Also you can get rid of radiators and free up wall space. Cons are that it doesn't supply domestic hot water. Several manufactures supply DHW cylinders that incorporate a heat pump. These have ducts to pull in air from outside and expel cooled air from which the heat has been extracted. They are then just plumbed into the hot water system. Products are available from Vaillant, Simplex and Daikin I think. Search Google for "Hot water cylinder with integrated air source heat pump" They are very popular in the US where they often use AC for heating and cooling too. All the best Michael

@@michaeldepodesta001 Hi Michael. I forgot to say we have wet underfloor heating throughout our ground floor so would not want to change from that. I’m looking for a different method of heating the water passing around the UFH pipes. I saw a Heatrae Sadia electric boiler that seems promising. One of the problems for an ASHP on our property is the neighbour on the side we’d need to install a heat pump. He objects to everything!! Keep up you excellent information videos, Michael.

@@stevesmith7675 OK I rather missed the point. But do consider alternative sites for an ASHP: going pure electric multiplies the bills (and the CO2) by a factor 3 to 4! But you know your situation better than I do: good luck with your installation! M

@@michaeldepodesta001 One last question, Michael. I have a 170L Heatrae Sadia unvented cylinder. If I were to go to an ASHP can I keep my current cylinder? It would save costs if I could. 😁

@@stevesmith7675 It depends, but I would guess not. Why not? A heat pump heats the DHW by passing hotter water through a coil inside. Here is a cross section of one: www.installershub.co.uk/product/rm-intercyl-unvented-twin-coil/?attribute_pa_capacity=300-litre&gclid=CjwKCAjwh4ObBhAzEiwAHzZYU_nc5EhtcTPVPfOGRU9gA1I0x335rIA44zIg_YvNOVkYVddsNGhTXRoClkMQAvD_BwE It may be possible to exchange heat between the DHW and the heat pump circuit using an external heat exchanger, but I am not familiar with how to do it. Nothing is easy! Sorry. Best wishes with your endeavours. M

Arpad Arpad, good evening. First of all, that's an impressively sized system both in terms of generation and storage. Depending on exactly which end of New Zealand you live in, your results would differ, but I would guess that would take you substantially off-grid for a solid 6 months/year. To understand how the system will behave in winter, you need to compare a few numbers. Firstly, peak winter heating load. To estimate this take the coldest day of winter and measure your gas consumption (if you heat with gas) for that 24 hour day. Depending on the size of your home this might be 100 kWh/day. With a heat pump you can deliver that heating with typically 33 kWh/day of electricity. So then the question is: can you generate 33 kWh/day in winter from your solar PV. My guess is probably not. My 21 panel system generates about 4 kWh/day in winter but heating demand on the coldest days is about 75 kWh i.e. requiring 25 kWh of electricity to operate the heat pump. SO you need to compare your peak winter load with typical winter generation - the most useful units are kWh/day. I hope that helps Michael

@@michaeldepodesta001 Yes, we are in Christchurch which is pretty good in terms of heating demand (that's probably the main reason why people reluctant to spend on energy efficient heating options), we barely have frosty nights, and the daytime temperature is pretty much always above 0. The difficult part to create baseline data. Heating a house here is basically ad hoc. The most advanced technology is using air to air heat pump, generally to heat one area in the house, or having the larger , ducted version, which is the closest to "central heating". Of course I'm talking about older houses, some new builds in colder areas has underfloor heating. In my case the house is about 30 years old. As we just purchased this house in December 2021, I have very limited data available, and that is electricity only (no other energy has been used). The highest usage was not exceeded 60kWh/day. Looking at the daily consumption during the summer months is in average of 15kWh/day, so we used approximately 45 kWh for heating per day (likely on a cold day), which included a 6kW air to air heat pump, and four electric heaters in the bedrooms (electric fan heater in the bathrooms occasionally). Needless to say the comfort is questionable when you have to go through on the cold hallway between rooms, not even mention other necessities in the smallest room in the house.. I'm sure we need to purchase electricity, as the winter production will be only around 20kWh on bad days. What I'm hoping for is topping up the battery during the off peak power, which cost less than the half of the peak power, with my power company it is between 9pm and 7 am, which is very generous.

@@arpa592 Hello again. Yes, we switch modes with our heating. When the average solar yield exceeds the normal household, we switch to self-sufficient mode: We charge up on solar energy during the day and run down the batteries over night. When the average solar yield falls below the normal household, we switch to grid-mode: We charge up on cheap electricity at night and then run off the battery during the day with the solar 'topping up' to some extent. Your are right, your electricity is being very generous with their cheap hours. We just get 4 hours! All the best Michael

Erald, Good Evening, It sounds like you are on top this: your comments are very sound. If you want to double check, then on these cold days coming up (December 6th in the UK) if you record your electricity and gas consumption over 24 hours of a cold day - read your meter 24 hours apart - with your home internal temperature as you want it - then you can measure the heat loss from your home directly. Just divide consumption by 24 to get the power of heat pump you require. E.g 150 kWh/day of consumption = 6.3 kW average power. I wrote about this idea here - with a few tweaks. protonsforbreakfast.wordpress.com/2022/11/07/what-to-do-on-the-coldest-day-of-the-year/ Regarding the fact that it is not necessary to insulate first, I agree. I think the insulate first idea embedded itself early on when heat pumps were and expensive and high tech novelty whose wonder must be 'earned by good deeds'. That kind if attitude is redundant now: we just need to get them in as fast as possible. Best wishes Michael

@@michaeldepodesta001 I'll do just that - thanks for the suggestion and all the other help.

"No house is that leaky". Lol hold my bear. 1904 detached house. Solid walls. Air vents everywhere. Had eight open fires places. To say I don't have my work cut out for me is an understatement. Was using 55,000 kilowatt hours of gas a year. I've got it down to 27, 000kWh of gas. I'm going to try and get it under 16,000 kWh by converting to a heat pump

As for your cylinder problem. Look at "sunamp" or alternatives Using vacuum insulation and phase change liquid. It only lose about just over a kilowatt of energy in 24-hour. It's also half the size of a normal cylinder

@@MichaelPickles Michael, Good Evening. If you use 27,000 kWh of gas to heat your house then (Depending on your use of DHW) your heating demand is probably less 90% of that i.e. 24,000 kWh/year, which suggests a beefy 9 kW maximum output heat pump should be OK - as long as the radiators have sufficient output. It's worth lowering the flow temperature of your gas boiler to 50 °C to see if the boiler can still heat your house at that flow temperature. But switching to a heat pump won't lower your heat demand. Best wishes Michael

Zoran, Good Evening. Putting a fan or blower underneath a radiator is a great idea. It improves heat transfer from the radiator and improves the heating power of the radiator - assuming the flow temperature remains the same. Alternatively, using a blower can allow the same heating power with lower flow temperatures. All the best: M

TY

Good afternoon. And thank you for your kind words. However I think you are *completely* wrong about hydrogen. We need hydrogen for many reasons (high temperature heating and chemical feedstock) but heating is a complete waste of hydrogen. The difficult and expense of making it will require that it's used in applications where it is irreplaceable. Hydrogen provide no alternative to using heat pumps. Best wishes Michael

@@michaeldepodesta001 totally agree for domestic heating (and I'm probably going to get a heat pump myself so agree it's probably the best solution for this use). But I work in the energy industry and can't see any substitute for some level of gas generation during prolonged periods of low wind (the so called "dunkelflaute") so converting natural gas CCGTs to hydrogen could be part of the solution. And there is no choice here - the O&G majors will be part of the energy transition whether people like it or not. Net zero comes at a huge cost and the economics need to work. But there will be endless debate on this fascinating topic!

@@gianpaologliori3604 In my understanding it is not so easy to convert CCGT to hydrogen. I am not aware that it has been done. The flame properties of hydrogen and methane are completely different. Given that production of hydrogen is so difficult and expensive, it would probably just be better to keep generating with methane as we do now during the low wind periods. Then - as has happened with coal - our requirements for gas will diminish year on year as renewable generation grows. What to do with the surplus renewable generation that we will soon find ourselves with? I think it's an open question. Synthesis of liquid fuels is one option, but I think there are a lot of long-term energy storage technologies with durations of days to months that may become economic. In any case: it's not today's problem. Best wishes. M

Yes it is possible to run at a flow temperature of 50 °C and a SCOP of 3 would be achievable. But please note the following. 1. 50 °C is generally considered 'hot' in the heat pump world and for some older heat pumps it is the maximum temperature they can reach without an addition resistive heater. 2. The link below is to the Vaillant Arotherm plus spec sheet. www.vaillant.co.uk/downloads/aproducts/renewables-1/arotherm-plus/arotherm-plus-spec-sheet-1892564.pdf If you scroll down you will see a complicated table labelled "SCOP and heating output". Look at the column label "50 °C flow". For the 5 kW heat pump this suggests that a SCOP of 3.41 is achievable. Great! 3. However I would recommend that you use the heat pump with weather compensation. This changes the flow temperature to meet heating demand. When teh outside temperature is 10 °C, for my system teh flow temperature is 30 °C, but when it falls to 0 °C outside, teh flow temperature is increased to 40 °C. So for you system, you might only need 50 °C on a few very cold days. Weather compensation is discussed at 37m10s into the video. Best wishes Michael

@@michaeldepodesta001 Thanks for the info Michael, the Vaillant data sheet is extremely useful. My heat loss calculations are based on a 22-degree internal temperature and minus 3 external (I feel the cold!). I live on the south coast so these conditions are likely to occur on just a handful of days each year, most of the time the flow temperature would be substantially lower. I will definitely follow your advice and have weather compensation.

Ken, I agree. Typical UK costs are £13,000 reduced to £8,000 with a government grant. I think it will reduce over time, but a heat pump itself is more complicated than a boiler, and a heat pump installation is more complicated than a boiler installation. SO I guess that explains the cost. But in terms of CO2 emissions, your heat pump will be a big win for the planet. Is the ASHP keeping you warm? M

@@michaeldepodesta001 the only way they can reduce costs is by cutting quality that's already going on . HP's may become cheaper but they won't last. they have a very hard life by working flat out in the worst conditions and far less in better weather longevity isn't in HP's DNA I've been in the trade since '82 and until cop goes up to around 6 at zero c by increasing compression technology I don't believe they are a good long life solution against a gas boiler unless air to air is used. air to water is still too inefficient.you'd need to add solar to realise true gains. however the world needs early adopters to drive the tech forward which it will 👍

@@richardbartlett6932 Richard, Hi. The longevity of the current generation of heat pumps is unknown - time will tell. "I don't believe they are a good long life solution against a gas boiler: The problem with gas boilers is that they emit tonnes of planet warming CO2 every year, and I don't think that is a good long-life solution for the planet! Best wishes Michael

Ken, the UK government is making things expensive with the rebate program requirements. Most places use much cheaper and just as effective air to air systems that can be bought for $1-2000. Sorry the UK is such a mess.

@@michaeldepodesta001 the co2 is a red herring look at total co2 then look at emissions and then look at boilers . I'm all for cleaning up the environment but MMGW is a nonsense and doesn't really bear proper scrutiny

Leichat Hi. Good question with an answer that is longer than I would like. As I explained in this blog article protonsforbreakfast.wordpress.com/2022/09/23/finally-off-gas-well-almost-finally/ we are using zero gas, but replacing the gas hob and cooker with electric versions required a compromise with my wife. And she 'suggested' that we keep the old gas fire in our front room for one more year in case there are Power Cuts this winter. I felt obligated to agree, but hopefully in the spring of 2023 I will be able to persuade her to disconnect the gas completely. All the best M

Hi Dilemma. I agree with you. I love some modern radiator designs, but I suspect the boring standard radiators with two or three panels and loads of fins are dramatically more effective. Thanks for the suggestion about a video: I'll add it to the list but I am bit overwhelmed at the moment! Best wishes M

(I live in different weather conditions and it would be pretty nifty to be able to provide heat and cold with the same system)

@FelipeBudinich Good afternoon. It varies from model to model, but many heat pumps can be run in reverse to provide cooling. However cooling through normal radiators is not very effective. If the flow temperature falls below roughly 10 °C then water will condense on the outside of the radiators - and drip onto furnishings. Instead of radiators, special units are available which maximise heat transfer - similar to the fan-coil units used in air conditioners, but still with water as coolant/

Peter, Good Morning. Thank you for your kind words. Yes, it is an expensive business. And I am a bit odd! Yes, I am trying hard not to emit carbon dioxide - and after retiring I had a pot of money to spend and I couldn't think of a better way of spending it. So I have no concern for return on investment which I know matters to most people. It sounds like you are already on a journey, and I wish you good luck with your endeavours. It really shouldn't be this hard to do the right thing! Best wishes M

Mike, Hi. Yes, the slide is correct. In this example the heat pump CONSUMES 1 kWh of electrical energy (in order to operate the compressor) and MOVES 2 kWh of heat energy from a cold temperature to a hot temperature. In all. 3 kWh of heat energy is delivered. Best wishes Michael

1 in + 2 moved = 3 total. So 3/1 gives a COP of 3.

@@davidreece1642 1 in + 2 MOVED = 3 out

@@michaeldepodesta001 yes, (now edited) moved not generated👍👍

Wow: That looks like a no brainer. Well done for switching! M

Man, I'm jealous, where do you live that you're paying 6 cents a kWh?

Good Evening Tesh. Mmmm. That's the opposite to the usual problem. 45,000 kWh a year is a lot of gas. Do you use a lot of hot water? In the rule of thumb I guessed that 5% to 10% of teh gas usage is hot water. If you use a lot more than that then a smaller fraction of the 45,000 kWh/year would be used for space heating. In any case, I would discuss that with your installer. If the installation isn't imminent then when some really cold temperatures come along, read teh gas meter 24 hours apart to get a decent estimate for the maximum power required to heat your home. Take the number of kWh of gas used on this cold day and divide by 24 e.g. 100 kWh used in one day: divide by 24 h gives. heat pump power of roughly 4 kW. I'd add a bit to make sure it could cope so probably a 5 kW pump would be fine for that. BEst wishes M

@@michaeldepodesta001 I guess you mean, they will need a pump that will be 5kW (electrical), but if working with a COP of 3, it will provide 15kW (thermal). Is that correct?

@@oaklejant That's correct. Heat pumps are specified by their nominal THERMAL output at a specified environmental condition with a specified water delivery temperature.

Damian, good morning. That's a fair point. But finding extra space inside a home is very difficult, particularly for those in small dwellings. So I see a thermino as 'heat storage of last resort'. All the best: Michael

Mohamed, good evening. I wanted to have to the gas meter removed last year, but with the political uncertainty last autumn (2022) there was talk of possible electrical power cuts. For that reason my wanted to keep the gas supply - we still had one gas fire - as a back up. But earlier this year we did have our gas meter removed. Hurray! protonsforbreakfast.wordpress.com/2023/03/27/the-gas-man-cometh-for-the-last-time/ All the best Michael

@@michaeldepodesta001 many thanks Michael. I am thinking of removing mine and wanted to have some advice. I am using your video as a good reference

Marijus, Good Evening. Yes, you are correct. A heat pump is broadly cost-neutral with a gas boiler at current prices. And it costs more to install. So how could I possibly recommend a heat pump to anyone in good faith? Because not every decision is made as a pure financial decision. Do people calculate the payback period on a car? Or a holiday? Or a new Kitchen? People make these decisions because they want the benefit and they accept the cost. Similarly, living a life where I know have done my utmost to minimise carbon emissions under my control makes me feel better each day. Many people are not in my privileged position. I accept that. And if you have something better to spend your money on, that's great. One of the other high impact options - if you have the money and location is solar + a battery. This will have a much faster payback. Alternatively consider buying shares in Ripple - and own a fraction of a wind farm. In any case: good luck and best wishes. Michael

Great presentation! I appreciate the simplified schematics showing the heat pump operation. Here in the USA, it´s a little more confusing as the efficiency numbers are stated as SEER (Seasonal Energy Efficiency Ration)for cooling and HSPF (Heating Seasonal Performance Factor). If you only consider the SEER, you could be way off on your condenser estimate and be left with an anemic heater. Also, in our Luddite system here in the USA, heat pumps are specified in terms of Tons of capacity while the gas units are BTU´s or Therms as opposed to KWH used for electrical equipment. For the average person, it´s a pain to convert units to compare apples to apples and get a resonable cost comparison. Also, it seems the most common domestic condensors are the cube types dominated by legacy American manufacturers-- e.g. Carrier-Payne, Trane-American Standard, York, Rhud, Goodman etc..). I see some of the brands you mention here as well but mostly for mini-splits or smaller units. Here in california, we´ve got approx. $0.30/KWH baseline with NG at equivalent of $0.125/KWH ($2.30/Therm). Soo...it seems here as well, the best you can do is break even unless you have home electric generation. The rate structure is designed to punish subscribers with higher energy needs and if the user´ś elex load increases--say, by installing a heat pump, they get penalized at $0.38/KWH..so loose-loose from a rate standpoint.

@@bigwave_dave8468 Dear Big Wave Dave, Good Evening. Thanks for the information on Californian pricing structures. Regarding US manufacturers I have seen those 'cube' type units on videos and been curious that European units just don't look like that at all. I think one part of it may be to do with space: you've got a lot more of it than we have in Europe or the UK. Also there is very tight regulation on noise which actually dictates quite a lot of the unit dimensions by the need to keep the fan tip speed low at even the largest air throughput. But even though the economics are currently marginal both here and in the US, I do have hope that that will change. In any case, all the best: M

@@michaeldepodesta001 Those US manufacturers i mentioned basically have a 3-tier modeling scheme (low, medium highest efficiency) They are almost all Cube types but it may also have to do with the average capacity being larger (coils around perimeter with fan flat horizontal on top of the cube) as opposed to stacking two units vertically to achieve similar capacity. I'm not sure about noise regulation here. Nobody seems to publish noise figures like they do for bathroom fans. Besides efficiency, quietness is my main criteria. oh one last thing -- it seems that here, Air-Air heat pumps are most common. likely since the housing inventory in the US is much younger. It's rare to see a house with radiators nowadays and hydronic heating is unusual in anything but expensive homes :-(

@@bigwave_dave8468 Yes, good thought. In Europe they just stack the fans to increase capacity. And yes, air-to-air makes lots of sense if you don't already have radiators. In the UK heating currently almost entirely from gas boilers with radiators (or under-floor heating in more modern homes) and for these Air-to-water heat pumps represent the upgrade path requiring the least internal re-modelling of a home. Sometimes I wish things were simpler... All the best Michael

Dear Tung Tung, Good Afternoon. The 2 kWh of thermal energy is removed from teh air outside your house. The outside air (which is already cold) gets even colder. And that thermal energy which has been removed from the air is used to heat your home. Check out this video for a slightly chaotic explanation of how a heat pump works. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-jDjBZ9GqFmc.html Best wishes Michael

@@michaeldepodesta001 Thanks Michael. If heat pump is replaced by a normal fan, the fan also moves 2kWh heat from outside into the house. Its efficiency can be said as 100% (ignore small loss in the fan). My understanding is: Heat pump converts 1kwh electricity to mechanical energy that raises the pressure applied to the refrigerant hence increase the temperature of the refrigerant. That in turn transfers more heat into the house. So heat pump is not moving heat only but also contributes to the extra heat in the house.

@@tungtung4229 You are correct that the heat energy used to operate the heat pumps also ends up in the house. Typically 1 kWh of electrical/mechanical energy is sufficient to harvest 2 kWh of environmental energy making a total of 3 kWh of heat which enters the house. I don't understand your comment about a fan: A fan blowing cold air from the outside into the home will not heat the home at all! Best wishes: M

Paul, Good Evening. I don't think so. Air to Water Air-Source Heat Pumps do offer the possibility of cooling with the use of special fan-coil units. But it seemed so complicated - extra pipework etc - that in my home I installed the ASHP without any cooling and instead added a small Mini-split AC (i.e. air to air) unit to provide cooling for my bedroom. They can also provide heat with a high COP if the ASHP is out of action for any reason. This probably saved money and definitely reduced the complexity of the installation.

Phil, Good Afternoon. It sounds like you are very much on top of the situation in your home: congratulations. However, you are only doing financial accounting. Do you do the same accounting for other things in your life? Do you calculate the Return on Investment and payback period of a new kitchen, or a car? When you you do carbon accounting, the calculations run the other way. Boilers emit tonnes of carbon dioxide per year that we have no way to remove. This is adding to the problem that we will leave to the next generation. The embodied carbon in a heat pump pays for itself in a year or two. Each one of us has to choose what we would like to leave our children: a pile of cash or a marginally cooler planet. Best wishes Michael

9000 pounds is a lot of money. I put in my air to air system for $1400, which was free after rebates. Reducing capital expenses helps the most with payback period, but the UK systems sound awful and expensive. :(

@@michaeldepodesta001 Boilers emit CO2? That's what plants take in. Don't say we have no way to remove.

​@@philware1546 Phil, Good Afternoon. CO2 cycles in and out of the biosphere in many ways. And you are right, plants do absorb CO2. But they don't absorb it permanently at scale. We don't have any technology that can remove *permanently* CO2 from the atmosphere *at the scale of gigatons or above*. There are possible technologies which might in a few decades, and they are worth developing. All the best Michael

@@motog6436 Hi. In the UK installation of air to air AC systems is strictly regulated. Installation must be by an accredited Fluorinated-Gas Engineer. This drives up the cost but improves the overall quality of installations. All the best. Michael

Dear Fritzy Babe - that is not something I thought would be typing this evening! First of all well done for planning early on. That's really smart! Regarding heat pump sizing. Did you record gas usage during the recent cold spell? If you did, try dividing your gas usage (say 150 kWh/day) by 24 hours to give you the average heat pump power in kW. I wrote about this here: protonsforbreakfast.wordpress.com/2022/11/07/what-to-do-on-the-coldest-day-of-the-year/ and here protonsforbreakfast.wordpress.com/2022/12/11/cold-weather-measurements-of-heat-transfer-coefficient/ These should give you very good estimates of the heat pump size you require. Regarding Peak Demand. In the second of those I plotted average consumption versus heating demand. In the days afterwards, things got even colder and peak demand was around 3.5 kW. So technically I could have got the smaller size (3.5 kW rather than 5 kW) but I felt 5 kW was no longer grossly oversized. But it is too big for most winter days which more normally require only 1 kW- 2 kW to heat the house. Regarding the Legionella Cycle. Yes, I do run one weekly in place of a regular cylinder top-up. It heats to 60 °C. Using excess PV to heat the cylinder is a smart first step, but it is way too much heating in summer. In summer we heat DHW in the afternoon when outside temperatures area maximum and the PV has generally topped up the battery already. This uses PV which would otherwise have been exported. Once that is done, we export the electricity. In winter, we heat DHW at night using cheap rate electricity. At 7.5 p/kWh and a COP of 3 this is very cheap. We also charge the battery using cheap rate electricity and then run teh heat pump with it during the day. When it's 10 °C outside, we can generally make it through to 11 p.m. or so before the battery runs out. When it was -5 °C we only made it to midday before the battery ran out and we had to buy full-price electricity. Anyway: Good luck with endeavours! Michael

Thanks for the comprehensive reply. Unfortunately I can't calculate using gas usage as I don't heat the house up! My house is enormous (16 rooms if you include ensuites for 2 of us!). I currently have 3 rooms + 2 ensuites heated for 1 hour a day (probably 3 hours on those really cold days last week). My office (I WFH) is heated by solar gain if sunny and a 1kw for an hour if not sunny. My gas usage runs from 21st each month and was 128kw Oct-Nov 690kw Nov-Dec. As you can see not high usage but you get used to being cold - many layers! I want to install a HP as I think I could have a higher background heat for very little running costs. At the Renovating show this year I was advised that the roof would support a 9kv system (subject to DNO approval) as the installer recognised the house design. That means very cheap heating with a battery installed.

@@MrFritzybabe Ahhh. Everything is always complicated. But with 9kW peak solar, batteries and a heat pump you should be flying! Good luck with all your endeavours. M

In the video (ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-n3AoUjuBixA.html) I explain the typical saving is small and I also say exactly how much my bill is. If you want to comment on the video, you might want to watch it first. Best wishes Michael

Gino, Important Question. I have discussed all the works and the cost in a couple of videos. 1. This quality isnty very good but the costs are discussed at 26m11s into the video. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-3Pr7wL63FjQ.html 2. This talk has the same slides with slightly better quality video. Discussion of costs start 13m10s into the video ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-E03O3qAZYx0.html Do ask if you would like more details. M

@@michaeldepodesta001 you are a star , I don't have a pc so using the smallest mobile in the world lol . cheers

Wow you have put some serious investment. I replaced every windows and door glass to k glass so I have now. Used secondary double glazing and wow what a huge difference that has made. I agree with regards east and west. This year I installed roof rails ready for another 6 KW of solar pannels to be placed in East and West positions so I will have at least 20 KW spread over the day. Tip for you boil a kettle and use flasks to keep water hot, then decant enough for a kettle the kettle will be quick to reheat as your water will be hot from flasks.

@@gino2465 What a wonderful kettle tip which I will be sure to try. Regarding the general costs, when I retired I had a tax free lump sum of £60,000 and I couldn't think of anything better to do with it than to try to reduce carbon dioxide emissions. If I had had less I would have done less: I would probably have slipped the external insulation and just installed a bigger heat pump.

@@michaeldepodesta001 good man , I am trying but the cheap way lol. My issue where I live is power outages and as I write this we are on our 12kw Diesel Genny. I invested in bigger to allow for EV charging and heat pump when I fit one. I will not go away from log for many years as I don't want all my eggs in one basket . I will work both together side by side .

Mark, Good Evening. The 2900 is part of a rule of thumb for estimating the maximum heating power required for a dwelling. I discuss this at length in this video ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-hCeghKa3liM.html In summary, it's got a factor for boiler efficiency and factor for the number of "heating degree days" in a UK winter - essentially the length and depth of winter. All the best Michael

I agree those incentives go the wrong way, but actually for me it's 360% efficient and a gas boiler is at best 90% efficient. And since I buy the electricity at night for 7.5 p unit, most of my heating costs 7.5/3.6 = 2.1p/kWh. I am quite happy with that. M

Ry, yes. I agree 90% is optimistic. A better choice might be 85% ± 5%. I chose to work with that figure because it overestimates the heating required in the house and thus tends to slightly overestimate the heat pump size required. Best wishes Michael

@@michaeldepodesta001 I currently waiting in for my octopus energy ASHP survey. So excited. From what I’ve heard and the number of people who octopus have refused to install for Im hoping these guys are doing a proper job! Solid wall property, with EWI, Triple Glazzing, PV & storage also for me the ASHP is the cherry on top! Fabric first approach on my 1940s hard to heat home apparently 🤷🏼‍♂️ I’ve found you channel so informative and I intend to recommend it to any one who ask about ASHPs

@@rymoe6299 Good Morning and thank you for your kind words. It looks like you are 'on a journey' and I wish you all the best with your endeavours. I do hope you have a good installation experience! All the best Michael

David Granger, Good Afternoon. I'm afraid I can't exactly understand your comment. Firstly, heat pumps don't produce "heat from nothing": They move heat from a colder place to a hotter place using mechanical work. Secondly I wasn't sure what you meant by WEF. Is that the World Economic Forum ? I don't know what that organisation is relevant to this video. Thirdly, a heat pump would not be used to move heat from (say) 0°C outside to the temperature of a gas oven at (say) 200 °C. But it can easily move heat from 0°C outside to 50 °C inside which is enough to provide hot water and heat your home. I did make an explainer for how heat pumps work which can see here: protonsforbreakfast.wordpress.com/2022/02/24/heat-pump-explainer/ All the best Michael

Brian, Good Afternoon. Indeed, no energy conversion has 100% efficiency, but it is interesting to understand that starting with methane gas, it is more efficient to burn it in a power station (50% efficiency) and use that electricity to operate a heat pump at a COP of 3 (300% efficiency) than it is to burn the gas directly in someone's home (90% efficiency). Best wishes Michael

Michael, Good Evening. The figures you have proposed are all a bit off as far as I can see. For my system: Summer COP is around 2.3 - because it pumps so little heat, the 20 W standby consumption becomes significant. In summer we are off grid and DHW heating is done via solar. Winter COP is closer to 4: Sept/Oct/Nov/Dec/Jan = 3.3/3.7/4.0/3.1/3.8 With the Battery I buy electricity at 7.5p/kWh and this provides over 90% of the electricity we use. We just top up on full price (42p/kWh) electricity at the end of the day. Cost per kWh of heat is 3 or 4 pence - way cheaper than gas. Costs for Sept/Oct/Nov/Dec/ = £18, £30, £62, £124. The government's £400 subsidy will pay the entire year's energy bill. And yes, this kind of set up is expensive, but it will only get cheaper. Best wishes: Michael

David: Good Morning. So your annual gas usage was 23,200 kWh which satisfactorily warmed your home. Have I got that right? Some of that was used for water heating (say 10%?) and some was wasted (say 10%). So the actual heating required for that year was 0.8 x 23,200 = 18,560 kWh. I would discuss with these installers how their space heating requirements can be justified given your actual gas usage. They will say "It's what the MCS process specifies". But in the end I think a nice ~ 10 kWh pump would satisfy everybody. If you are sticking with gas for another year, try reading your meter once a week and getting the average weekly temperature near you from Weather Undergrounds 'Wundermap'. Then you will definitely know how much heating your home requires. In any case: Good luck with your endeavours. M

@@michaeldepodesta001 All assumptions are correct. I've had the MCS process spec discussion and neither installer is willing to budge (which means the £5k grant isn't happening). I'd be happy with a 10kW ASHP as insurance. My gas boiler's 11 years old but still working OK so I'll read the gas meter weekly and the Wundermap average weekly temp (what a fantastic resource) as you suggest. Thank you so much.

@@michaeldepodesta001 could you please point me to your explanation of what to do once you have the weekly usage and average temperature. I'm sure it's a straight forward calc. Thanks for doing so much positive action!

@@pumpkinhead456 Drop me a note at house@depodesta.net and I will send you a spreadsheet template. M

@@pumpkinhead456 Dear Pumpkinhead, Once you have the data, there are a number of ways to proceed. And if you worry about details things will get VERY complicated. So this is simplified - but if you get how this works, maybe you can think of ways to improve the estimates. Let's suppose you have week by week data on gas consumption and week-by-week data on average outside temperature. Step 0. Divide your weekly gas consumption by 7 to give the average daily gas consumption during that week. Step 1. Work out the difference between your average indoor temperature and average outdoor temperature: this is your temperature 'demand' - a measure of how hard you are asking your heating system to work. Step 2. This is cosmetic and you can skip this if you want. Plot both 'demand' (°C) and and 'gas consumption' (kWh/day) versus week of the year. You should see they correlate closely. Step 3. Plot 'gas consumption' (kWh/day) on the vertical axis (y) versus 'demand' (°C) on the horizontal axis (x). You should see a sort of slope with the biggest consumption being when the temperature demand is greatest. Step 4. The slope of the data near the peak demand is an estimate for the heat transfer coefficient of you house (HTC). The units are kWh/day per °C. A typical (large) value might be 10 kWh/day per °C. Convert to W/°C by multiplying by 1000/24 i.e. 41.66 i.e 416 W/°C Step 5. To get the heat pump power required, multiply the HTC by the maximum likely temperature demand - usually around 20 °C in the UK. This is the maximum heat pump power required i.e. 416 W/°C x 20 °C = 8,320 W or 8.3 kW. Buy a heat pump with a maximum power at low temperature just a little bit greater than 8.3 kW. Or actually 8 kW would do - if you get cold one just or two hours on one or two days a year you can just put an electric heater on! protonsforbreakfast.wordpress.com/2021/02/15/understanding-heat-flow-in-my-home-the-key-graph/ The above blog article and ones I link to it may help. Do drop me a line if I can help further! Seriously! Best wishes Michael

Hi Mike. Why do you say that? If a heat pump delivers the same heat as a boiler, how can it not be equivalent a boiler? Best wishes Michael

@@michaeldepodesta001 that's your view. I have seen plenty of other reports saying the exact opposite.

@@mikeuk1954So you have read reports but don't have any personal experience. Mmmm.

Hi Mike. Do you have any links to these reports? What reasons do they give that a great pump with the same heat output as a boiler won't work?

@@ferguswalker7345 It is easier to mis-install a heat pump than it is a boiler. Here is one way this can happen. Heat Pumps with a high heat output (say 10 kW) deliver that heat at the same temperature (say 40 °C) as heat pumps with a lower heat output (say 5 kW). To output more heat they simply flow water faster through the pump: Say 20 litres per minute rather than 10 litres per minute. If the pipework in the house is too narrow, then it becomes impossible for the pump to move that much water through the pipes to actually deliver the heat to the radiators and the house. In part this kind of installation fault arises because inexperienced installers will focus on the shiny 'new thing' that costs thousands of pounds, and not think about the heating system as a whole. So it is also possible to attach a 10 kW heat pump, but find that it can't deliver 10 kW of heat to the house, which results in a mystified and disappointed customer. But it is also possible that with a little bit more thought, that same pump could happily deliver 10 kW to the house resulting in a delighted customer. Best wishes M

Dear Snarky User, good evening. Restricting the use of AC at peak summer demand is something that I think is still voluntary in most places. For example, in the recent California heatwave text messages sent to users asking for voluntary reductions in electricity use - mostly AC - managed to avoid the need for power cuts. But heating is different. Heat pumps are 300% efficient and represent the lowest energy way to heat any home or business. Anyone with the power - which I don't think exists - would turn off electric heaters and gas boilers both of which waste energy compared to a heat pump. Best wishes Michael

Grazie

Thanks: Sorry, It's a silly error and I made a note of it immediately in the notes below the video. All the best. M

AR: Sounds like you have had some bad experiences. But I urge you not to let that colour your judgement. Regarding Heat pumps, my heat pump will warm water to 70 °C if I want and my house sits at very comfortable 20 °C no matter how cold it gets outside. And it - combined with other CO2 reduction measures is saving me thousands of pounds a year:. The article below was written before the current government subsidy. With the subsidy my annual bills are practically zero. It sounds to me like the installers were not competent. protonsforbreakfast.wordpress.com/2022/08/26/non-je-ne-regrette-rien-update/ Regarding electric cars, the Nissan leaf is a very old car and new technology is much better. In any case, keep warm. M

@frederickbowdler8169 Good Evening, Reliability is an important issue, and it it is yet to be really tested in practice because heat pumps have not been installed long enough. But the technology is similar to that in domestic refrigerators and air conditioning units, both of which are spectacularly reliable. Was it something specific that caused you raise this concern? Best wishes Michael