Octopus Energy Heat Pump Installation Part 3 - Days 4 & 5 

Thank you, that's good to have that feedback!

Yeah it is huge and I can understand why people wouldn’t have room for one.

Thank you!

That's a neat idea. Problem is mine was being changed from a vented to an unvented system so depending on the temporary cylinder type there was a fair bit of work required to get it working!

Woah yeah I wouldn’t want to be going into the loft all the time to keep an eye on it!

@@SpeakToTheGeekTech we’ve got a remote “master” thermostat, but programming the hot water timing, flow temps, weather compensation all have to be done from the control panel in the loft. The Wi-Fi dongle is £200 or so and I’ve heard it’s not that good either. Have seen a video on connecting the heat pump to Home Assistant via modbus so that’s another future project. Always stuff to do!

Three-phase? You are serious about this then :) I'll investigate Tendra, I was looking at Eero because of their guaranteed 5 year support promise on updates. My Asus ZenWifi mesh is creaking from lack of updates in over 18 months now so I need to swap it for something else.

@@SpeakToTheGeekTech I managed to get the three phase connection free of charge from our DNO & their doing all the work too, so was a no brainer for us, is a bit more work & cost but think be worth it as also have a zappi 22kw fast charger along with heat pump, solar & battery, also means I can have a 10kwh inverter on a G98 from the DNO so be able to make the most of the dfs events. A friend has the Eero system which I think has also been fantastic so be also a good shout Will be using your referral code in March when I switch to octopus too 🙂

Thank you very much, I really appreciate whenever anyone uses my referral code. It's exciting to see a new referral pop up and watching when they go live in my account!

@@SpeakToTheGeekTech it's the very least I can do. I've just jumped over to X on the post with this video on to show you pics the three phase meter box I've had installed 😁

Thank you very much sir!

All planned for future videos :)

I'll cover the noise in a future video. It's true it's not silent, but it's no worse in my opinion than the boiler was. I've even been told by a Samsung heat pump owner that it sounds quieter than theirs.

The HA add-on is great but doesn’t supply all the data a geek could want… but there are other options!

@@SpeakToTheGeekTech the energy overview was it a HACS integration.

Yes, check out "Daikin Residential Controller for Altherma" which I'll demo in a future video, but also ESPAltherma if you're competent with electronics - I have ESPAltherma hooked up to read live data from it and it's brilliant.

A couple of reasons - new tank had to be a certain size and wouldn’t fit in there, but also building regs don’t allow the tank to go there now because it would be over the stairs so I’m told

I have access to the installer profile and can adjust it, but I need to do some reading and learning to get to grips with it.

Already set up :)

@@SpeakToTheGeekTech ahah! That would be epic content

Getting on very well. Water tanks give you flexibility of being able to heat water off peak, but of course you lose the unlimited on demand hot water a combi provides. There are solutions for that such as inline hot water heaters (I’m told they are very popular in the US). It’s not a one size fits all solution but there’s always viable options to replacing that combi

A 'combi' boiler is only really good for a shower... in every other way, they are inferior to 'heat-only' or 'system' boilers. Sadly, the British general public, generally, don't understand any of that... and love 'combi' boilers. ASHPs are defo an improvement on 'combi' boilers... but if you already have a perfectly working gas boiler of some sort... just carry on as you are !

My last two combi boilers could only support one shower operating at a time - having two bathrooms this can be inconvenient! Hot water tank means I can run two showers full pressure no problem!

@@gregevans8939I think whilst on paper yes I completely agree that system or heat only boilers are better and having a tank, a lot of people don’t need to tap off lots at one time and they like the simplicity and ease of the combi, more of a “heats my house, and when I turn a tap on, hot always comes out”. I completely agree with your points, but a lot of people I think are just not interested in any change to what just works currently.

​@@gregevans8939 a shower , what are you talking about , a combi boiler provides unlimited hot water , unlike a hot water cylinder which runs out , gas combi boilers are better than any other heat and hot water source available today , and cheaper , and you have more space , be interesting to know how much this installation cost , plain and simple these are the reasons the UK love gas combi boilers

There were three guys, one electrician plus two installers. Oh and a couple of gas guys turned up to isolate the supply for an hour or so at one point.

Thank you. The reason for the tank going in the garage was two-fold. Firstly they told me the MCS requirement for new tank size was 250L, and that would be physical too big to fit in the cupboard. Secondly they say they aren't allowed to put water tanks over the stairs anymore (building regs I guess) and my airing cupboard is directly above the stairs.

@@SpeakToTheGeekTech thank you. When you do another recap video about the really cold weather we had recently, if possible can you also do another Apple Watch dB check when it’s under load?

During the milder December it was between 6-12kWh/day. I will be doing a video all about energy use once I've got more data though.

Oh, sorry - and one single controller in my hallway for the whole house. It's just a single zone too. I am wondering if additional monitors around the home might be possible to improve comfort levels.

The lagging is about an inch thick outdoors, but it’s protected insulation specifically for outdoors. There’s an electric feed to from a consumer unit in the house out to the heat pump, then a second connection running from the heat pump along with the pipes to the MMI and components there (immersion, MMI, diverter, etc)

Amazing thanks. Also, the nice little wooden structure that surrounds the pump and gravel stones… I don’t suppose you know if that’s a standard thing Octopus do as part of the install or was it they either did specially for you or you partially built beforehand in preparation? Thanks

@@kieranmistry2659that wooden structure is the soak away and Octopus built that. It’s standard if there’s no drain nearby. The options are a soak away or direct drainage

Thank you very much! I had the email through so hopefully the switch goes well for you :)

I've found a way to get the pressure data out, video on that in a few weeks :)

@@SpeakToTheGeekTech Nice one, glad you got something sorted :)

Oh yes, lots of data! I haven’t recorded that video yet though but it is scripted ready

@@SpeakToTheGeekTech Awesome, I'll definitely be adding mine then

Thank god, can't wait, I'm waiting on my octopus installation (June 2024) and home assistant was a real worry after they said my nest won't be compatible with the heat pump

It’s the Mira Activate, an amazing shower! I plan to do a video on that in a few weeks

@@SpeakToTheGeekTech Cool, I look forward to it!!!

I'm not sure what it is, but it's like a slightly stretchy foam tape.

It should be glued together !

The hard foam ones should be glued but I think these are soft with a vinyl skin.@@gregevans8939

It's difficult to get your head around - the short answer is it works just like any other heating system, you tell it what temperature you wish the house to be and at what times of the day you want it at that temperature. So if you want the house at 20 degrees twice a day, set that in your schedule, but you also set what you want the temperature to be in between. I let it drop down to 18 during the day and 16 at night. But.... what kills efficiency is the initial heat up. Once up to temperature it suddenly becomes massively efficient to maintain the temperature by ramping down the power used to just what is needed. The longer it runs in that state for each initial power hungry heat up then the more efficient it becomes. Imagine running it for 2 hours to heat your house up, it gets 200% efficiency, but run it for 3 hours and it gets 400% efficiency for example. Some gas systems can work in a similar way, OpenTherm for example, but they will never reach the efficiency of heat pumps.

@@SpeakToTheGeekTechheat pumps get their efficiency when they are not running hard. Imagine a bicycle pump. If you pump hard then it gets warm quickly but you expend a lot of energy. If you want it to get a little bit warm you’d be pumping less hard. Heat pumps are capable of putting out a lot of heat but are less efficient doing so. Your analogy isn’t quite right on the 400% efficiency as the initial efficiency would be much less and then increase as the heat requirement reduce. The problem is that it does depend on a number of variables as to which is more efficient (and good design and installation as well) For me I am out of the house at work for quite a lot of the day and my desire would be to have the house warm when I come home. If the heat pump cannot raise the temperature quickly enough I will be using more electricity to heat a house when I am not in it. Unfortunately Government greenwashing and fly by night installers are going to make this a nightmare when boilers are banned. Spare parts will signify the end of a lot of boilers and you won’t be able to install a new one at some point so it’s an effective ban. Frankly subsidising insulation would be a better option in my opinion

Yup... future video though!

I looked at open energy monitor but it would have meant putting a flow meter into my existing ASHP plumbing to measure energy generated. Not something I wanted to tackle even as an enthusiastic diyer !

Yes there's a small buffer / bypass tank installed

Hi. No Octopus didn't install OpenEnergyMonitor. I've been told they've done it for others if you ask them in advance and supply all the parts, but I have gone down a different route (will be shown in a couple of weeks in another video). They replaced the shower controller for me because they had to re-plumb the whole airing cupboard anyway and swapping over the unit while they were in there made no difference to their timings. I did however swap over the user controls end myself - they would probably have done that for me if I'd asked, but they were massively busy. The didn't brick up the flue, but they filled it with expansion foam and put a fan grill over it. Personally I think that looks neat enough but there have been comments suggesting otherwise. I've looked at Homely yes and it's something I might consider over the summer, but for now I'm sticking with the supplied controls to get a nice baseline this winter.

Thank you for your reply. We are looking forward to our HP installation.

10mm, no tail pipes changed at all, and yes there's a buffer which I was told in part is because of the 10mm pipes. I've not kept the smart TRVs - they have all been sold on eBay!

​@@SpeakToTheGeekTech Thanks. Will be interested to see how you get on. We have 10mm tails too. I don't really want them replacing but I'm not keen on a buffer either as I've read they should be avoided if possible. Great videos. Thanks again.

Cylinder is 155cm tall and 62cm diameter. Buffet is 81cm tall and 31cm diameter. Both need extra space for pipes though.

Yes it is hardwired there using existing wiring.

The hot water tank is heated to a lower temperature of 48 degrees (apart from on legionella cycle days) which is perfectly fine for baths and showers, but of course you need more hot water in a mixer due to its lower temperature. We have a 250 litre tank and we easily get 3 showers. I wouldn’t want a smaller tank though. I’m surprised they are getting it working on 10mm plastic. I have 10mm copper and that’s the lowest they told me they do, plastic has a lower internal volume I think. But their system designers appear to know what they’re doing.

Yes they assure me the plastic pipes will work, despite the reduced volume - but I'm a tad anxious about this. They told me they wouldn't do 8mm plastic but 10mm plastic is fine, seems we are being told different things. Just wondered what sort of COP you are getting at the moment given it is so cold? I think our design temperature is 21C in the living areas, 18C in bedroom & 22C in the bathrooms. Probably a bit hotter than we need, do you find by tweaking the thermostat lower, you can improve the COP - we were quoted an average COP (heat & hot water) of 3.19 which is not brilliant, but as we have solar & a storage battery I think it will still save us quite a bit on our gas boiler. Also wondered how many KWH the system is consuming daily atm? Many thanks for your help, very much looking forward to your next video update post install - it's been a massive help as trying to find anyone who has had an Octopus HP install is next to impossible. Thanks again

I’ll be covering all of that in future videos, but rest assured all values/running costs are reasonable!

I opened it up and took a look inside :) There's a regular-looking Grundfos branded central heating pump inside the heat pump itself. Good luck with your install!

@SpeakToTheGeekTech That's great, thanks for the info. Fingers crossed that our install goes as well as yours!

Yup sure will do

There's no cement that I know of - the holes were cut quite large and the pipes running through them are lagged. I can see the lagging coming through inside the house

I was looking at 3:33 and I can't see the lagging, just the pipes entering the garage @@SpeakToTheGeekTech

Ah I can see why you're thinking that now. That's a trick of the light - those are freshly cut open holes in the brick which are the same diameter as the pipe lagging. They hadn't fitted the insulation at that point but it was done later on and is a nice snug fit completely sealing up those holes.

Yup, I replaced the whole thing with the same shower but for high pressure systems. I love that shower!

Thanks for the reply, yeah it’s a fantastic system but the pumps are expensive, did you just replace the pump or the whole shower, mines not that old so wouldn’t want to replace the whole system.

I mulled this over for a while and eventually just bit the bullet and bought a whole new system from plumbworld. I then boxed up the old one and sold it on Facebook marketplace to someone who could make use of it. Got £150 for it which helped but I had always known I would need to spend a fair bit to replace it. I went from dual to single outlet too and the user controller for that is slightly different too so it was a good job I replaced the whole thing!

I had solar and a couple of GivEnergy batteries installed yesterday, heat pump is the next upgrade, I’ve paid a deposit with Octopus last October and still waiting for the survey. They did say it would be in the new year and probably not installed till summer. Thanks for all your excellent videos, they have been a tremendous help.

The circulation pump is inside the heat pump itself, sorry forgot to mention that! I opened it up to have a look and there's a Grundfos pump inside, and there are no other circulation pumps on the system at all. The 'Esme' device is definitely a type of motorised valve for the hot water. I've seen it move back and forth as the hot water kicks in!

I think there’s a pump inside my LG ASHP as well, but I’ve got two external pumps in my system as well in a push pull configuration to ensure decent flow rate. All depends on the system size I guess

@@SpeakToTheGeekTech It would be nice if my circ pump was outside, it’s the noisiest part of my installation

I was pleasantly surprised to find the main circulation pump was in our Daikin unit (also an Octopus install). The motorised valve is a three way valve to switch between heating and domestic hot water - you can over ride it manually if you want by turning it (although no reason to). Check the controller - information - actuators to see which it is doing and whether the compressor is on. You may be going to pull that data into Home Assistant as most people who get into the data want to track starts per hour to watch for short cycling in mild weather. I’ll be interested to see how yours does compared to ours.

@@DavidBarker-fv1vg sounds like lots of great HA stats available with the Daikin. No such luck with LG. On the subject of short cycling, one time one of our pumps got stuck and the installer came out to free it, but in the process he gave the system a general health check. On the Honeywell master room thermostat he changed one of the config settings to avoid short cycling - basically a delay on the stat for when it’ll call for heat again. Might be worth seeing if there is similar on yours as this setting wasn’t the factory default

Honestly I've not used the integration in the Octopus app - it was interesting at first as a novelty but the practicality of it is that I have the Onecta app or Home Assistant control, both of which have far more control options than the Octopus app.

I previously had a Mira Activate pumped digital shower which was installed because the pressure from the tanks wasn't great. That shower does not work (big warning stickers all over it!) with a mains pressure system such as that used by the heat pump. The 'box' was a pump and a control box all in one. I purchased exactly the same shower (so another Mira Activate) but the model designed for mains pressure instead. Because it's a digital shower, the 'box' is now no longer a pump, but it still mixes the hot and cold water to output at the requested temperature, and regulates the pressure. The water pressure is now less than it was with the pump, but it's still a good pressure. There are many other shower options available, I just happen to really like the Mira Activate and wanted to stick with it.

Thanks for the replay, they need to remove my shower pump and was worried it would be unusable been waiting forever for the install going to be end of April before they install. Thanks for posting it gives me a much better idea of what to expect come install. Look forward to the updates. @@SpeakToTheGeekTech

Expanding foam and a plastic vent cover both sides. Looks neat enough to be honest and it's only a single skinned brick wall. I have whatever curve they set, not sure how to describe it really and I ned to read up on that.

@@SpeakToTheGeekTech So are you running on weather compensation now?

@@normanboyes4983 yup

@@SpeakToTheGeekTech Have fun homing in on the best curve for your home.👍

Yes, the flue hole is filled with expansion foam and a plastic grill over to make it look nicer. Looks neat to me. The cat flap is on the garage door anyway and is the least of my worries over heat loss in there! The uninsulated tile roof above it all for one thing! The rest of the house is nice and cosy though and very well insulated - keeps its heat really well for hours.

Octopus filled it with insulating foam and covered that with plastic vents for cosmetic reasons. I personally think that looks neater than a cement repair but many other commenters disagreed!

AHH just found the answer in one of the comments about them using expansion foam and a grill :)

It's only been a few weeks rather than months but I'm liking it especially compared to the boiler. I'll be putting together a 'first month with the heat pump' video in Feb.

Moving a mesh node to about 2m away from it seems to fix it. Strength is now showing -45dBm instead of -90 and no drop-outs!

I hadn't noticed they'd moved it? Nothing to do with me! I let them crack on - my only request to them was about the size of the soakaway outside.

All good so far, I've had a lot of people asking me this so there's a video on its way in a couple of weeks. Daikin cloud integration works fine via HACS, and if you're electronically minded you can build something called ESPAltherma to get data direct from the heat pump.

@@SpeakToTheGeekTech thanks I’ll take a look! Does that go inside the HP or on the MMI?

ESPAltherma goes inside the heat pump itself. All done at your own risk!

I paid extra to change all of our bedroom radiators because I didn't believe their sums. Cost me another £180ish I think and I'm glad I did that. I think they would have been underpowered otherwise.

@@SpeakToTheGeekTech we had no way of knowing that their sums were wrong. 3 surveys! You would expect them to get it right!

Yes they did but I've forgotten - I can always read up in the manual if I want to though!

Page 147 of the installer manual! Also, if you have always used thermostat control to the same comfort levels you can calculate your curve using old smart meter data for gas usage. Truly geeky then!

I was surprised to see all that stuff in the garage. I'd been looking into heat pumps and I thought it would just go outside and the pipes would simply connect into the existing heating system (with the boiler removed). Is the immersion heater required?

Yes, it needs a lot of space and there's no hiding that fact. If I compare it to my old heating system there's probably 30% more stuff! It's all in the garage now rather than being split between the garage and airing cupboard so looks worse due to being in one place. Smaller houses will probably need a different solution though, but this solution works for my home.

Yes, there needs to be another solution, we don’t have a garage or space for all of the additional stuff, there are many thousands of houses lacking this space.

6kW heat pump and a 250 litre tank

I’ll be putting together a costs video at some point because for me it’s not as straightforward as saying it was £x. Our indoor setpoint in the morning and evening is 20, during the day it’s 18 and over night it’s 16. No the radiators do not get as hot as before but they are warm to the touch which is expected - the old boiler basically ramped up to nuclear mode and wasted a lot of energy, heating at a lower flow temperature (between 30 and 45 degrees so far rather than 70 like the old boiler) uses a lot less energy.

The idea of radiators getting 'hot' is very much linked to old gas/oil/solid fuel systems. The way an ASHP system is designed means that rather than the radiators cycling from zero to 70°c to heat a room... they are at a constant 40°c (say). This is one of the ways that makes ASHP so efficient. Having said that... some people, for whatever reason, expect the radiator to be too hot to touch, and if it isn't, will complain that the system isn't working... even though the room temp might be 25°c !

@@gregevans8939 I guess its more a mindset thing with people like myself on legacy systems.

@@gregevans8939 My wife!

I have a wife too and this is the main reason I am unlikely to be investing in a heat pump in the near future. If she sees this series of videos I will never get one! Don't get me wrong, I am not opposed to heat pumps but I really don't need the grief as I spend enough time in the doghouse as it is.@@Richardincancale

Yes, the garage wall is only a single brick thick so they put expanding foam in and a fan grill to tidy it up. Looks quite neat on the outside, I have no complaints about the approach although I've had lots of comments to the contrary. Finding matching bricks and then neatly repairing the wall would take a long time and the most likely outcome would have been a mess! I think the vent approach works well.

@@SpeakToTheGeekTech I guess into a garage you just need something weather proof. My boiler flue goes out through the roof of my utility room, but hopefully matching and patching roof tiles is easier than bricks! Thinking to up my battery storage this year, with the 0% VAT change, and then replace the 2017 combi boiler with a heat pump next year. Just need to figure out water tank placement...

It's a new thing I was told, the installers talked me through adding the device to the app. I can't remember the exact steps but it was obvious when you add a new device and select Daikin heat pump. It then asks you to authenticate with your Daikin credentials and after about 5 minutes it pairs itself.

@@SpeakToTheGeekTech do you have a car or charger linked?

No, but hopefully the GivEnergy charger I have will be supported very soon

@@SpeakToTheGeekTech it will be nice to have the charger and heat pump together, let see if Octopus can sort it. If they add Solaredge into the ecosystem, they could have full control of the house.

It really depends on the temperature. It's been very mild so far and I guess it's using maybe 6-12kWh / day so far. But temperatures are dropping so it's going to go up massively I imagine. Feel free to browse my My Heatpump data to get a better feel for it. unpraying-ape-8145.dataplicity.io/app/view?name=ASHP&readkey=82af8f22985d47049461f3fbbc16632a

Impressive SCOP ! Can I ask what the heating requirement is for you house ? (kW @ outside design temp @ inside design temp) and how many square metres ?@@SpeakToTheGeekTech

110 sqm. Design temp is for 55 degree flow at -1.6, and inside temps varying between 18 and 21 depending on the room. I think I show the radiator schedule in one of my earlier videos in this series.

@@SpeakToTheGeekTech Is that 141 kWh for the whole house? So about 9 kWh a day since December 22nd?

Did you have a heat meter installed to get that heat output data, or is it the Daikin ONECTA data? I asked about having a heat meter installed but Octopus said they are looking at it but weren’t able to offer yet. They may have subcontracted it but didn’t offer to do so with my early November install. I therefore have energy input monitoring only.

35-45 celcius depending on the weather, it's on a weather comp curve so adapts as needed. It could go up to 55 if it got really cold

Just 2 that I can see and there are bypass valves in place too I think

@@SpeakToTheGeekTech Thank you, my primary interest is that I'm having the very same heat pump fitted in February, a Daikin 6kW, for heat loss 'calculated' at 5.2 kW. As part of the instal a 25l 'buffer' tank will be fitted, I'd assumed that it would be used as a volumiser, as I will only have seven radiators. My understanding is that its primary use will be the defrost cycle, as my primary flow and return to radiators will be 22mm, with 15 or 22mm tees to radiators, so should have fairly good flow through heat pump.

Class as in power rating? It's a 6kW one.

Yeah, I'll be honest it would have been better if they could have done that, but having seen what was involved to get it working (I was observing a lot!) I can't see how they could have done it all in one day. They would have needed 1-2 more people on the job I think. Just to summarise what was needed, they'd had to have panelled the wall in the garage, run the pipes through from the utility room for cold / hot, strip the airing cupboard and re-work all of the plumbing to convert it from vented to unvented, and replaced my shower all in one day. More people on the job would have made that possible I think, but what was positive is all details of the scheduling like this was fed back to the central team and I'm sure they'll be learning from it.

It's telling you about the wifi signal between your heating controller and your wifi network, nothing to do with your phone's signal. You fix that by putting in a wifi extender or additional mesh node near your heating MMI (the fancy control panel, not the indoor thermostat)

@@SpeakToTheGeekTech I probably wasn't clear enough. What I meant is that the location of the Daikin MMI controller is in area of good WiFi coverage, as proven by the WiFi signal my phone receives in the same location. Although Onecta always displays that there is poor WiFi, it still works.

Same here. I assume it's because the wireless adapter for the MMI is a small card with an internal antenna and surrounded by metal pipework. My GivEnergy AC-coupled inverter is nearby too and struggles but putting an access point right next to both of them has solved the issues.

Mine certainly get warm and they need to. There are thermostatic valves on them all so for a couple of upstairs rooms I've actually set them to the middle value '3' which I think is about 20 degrees. Two bedrooms were getting way too hot as backed up by a temperature sensor I put in them. Single zone for me though, no complications.

18° is typical for bedrooms... (too hot for me though !). Don't get fixated on the temp of the rads... measure the room temp.

You need to balance your radiators. Unless of course your rads are too small for the room’s heat loss. Why on Earth do you have three stats?

​@@normanboyes4983no idea, bought the house this way. But it's 3800sqft so I assume one is kitchen and hall, another sitting room and another bed rooms maybe

@@ITB_News It’s the wrong way to run ASHPs - best open loop, no room influence (thermostat) and run on weather compensation at the lowest setting to maintain satisfactory room temps. Zones and stats just cause cycling.

Seems to be working quite well so far. I’m under no illusion that it could be more efficient if the pipes were upgraded but that would be extra cost and work to the house. No reason why I couldn’t opt to do that in the future if I felt like it. Given I had a boiler about to fail I don’t consider it a waste of time

The whole system needed to be converted from vented to unvented so they couldn't have put the cylinder in until the plumbing had been done, and also the boiler needed to be removed too in order to fit the new cylinder in properly. Quite a complex chain of dependencies really, I'm sure it could have been managed better and I'm sure they'll learn from the order things were done in, but all-in-all it wasn't a problem for us and I'm pleased with the system.

Is it really? Where did you see that information? Mine is only a 6kW anyway for a home of 110m2

@SpeakToTheGeekTech 6kw is ok I think. Info about >9kw is on open energy monitor forums

@@muso31 Spotted one post like that, not sure where the 16kW out is derived from as the EDLA09DA3V3 technical spec' shows 9kW out at 45C LWC.

@_Dougaldog looks like its internals consist of the same circulation pump, compressor and the same minimum operating level as the 16kw version, which makes it the wrong size for the multitude of homes it's being installed in. Due to this I'm holding fire a few months on my octopus installation

9kW rated output modulating down to 900w is ok and should be similar across other brands as most ASHP have a modulation ratio of 4:1. For example the Vaillant Arotherm Plus 7kW will typically draw a max of about 3kw and a min of about 600w. Minimum modulation and potential short cycling is one of the reasons to have a buffer tank installed.

Until this week the odds would have been very low, but we have guests staying and it turns out we all want showers at the same time :) Oh well, not quite enough mains pressure for us to have two showers at the same time here it turns out, but a 5 minute wait for your turn is acceptable of course!

For what?

Haha Heat Geek Adam is most welcome to come and inspect if he wished to do so but I'm unlikely to be on his radar!