if you want to see the difference between the COP for hot water vs heating, looking in in the yield figures on the Vaillant wall unit. (the one with the 'volume' nob in the middle) you can see the 'working figure' which is Vaillant's term for COP. you can see daily monthly and total cop for each of hot water and heating separately. people say its not that accurate but as a comparison between heating and hot water is useful.
Great point, thanks for commenting Joe. I often forget about the COP figures on the Vaillant panel because we have dedicated electricity and heat meter that were installed as part of our installation. But definitely helpful to point out. Thanks Tom
@7:38 Worth the distinction - the heat pump doesn't have the immersion heater, the cylinder does, and with some heat pumps (i.e. R290 ones), the immersion in the cylinder can be completely disabled.
That’s a fair point. Sorry if I was misleading or confusing! I do get a few comments saying that a heat pump isn’t efficient it just runs off an immersion coil. So that misunderstanding is common!
@@TomBray-LowCarbonLifestyle Yeah, I knew what you meant 🙂But as you probably know, there are people who will jump on it saying "See, heat pumps do have an immersion heater", when in reality it's only used for Anti-legionella in non-R290 (mostly R32) heat pumps.
Hi Tom, we're looking at a couple of quotes for Solar PV + battery and both include a Solar Diverter to heat our water tank. We have a non condensing Glow Worm boiler which I've set to come on for half an hour to heat our water. Once we've got the SolarPV / battery sortd then an ASHP will be next on the list. Just wondering if the Solar Diverter would mean that the ASHP wouldn't be needed for water heating? Great content, well presented 👍
Hello! Thanks for the comment and encouragement! Interesting point about the solar diverter. And yes I imagine for lots of the year your boiler / future heat pump wouldn't be needed for hot water if you can dump excess energy in there. One thought though... if you used your heat pump powered by the solar generation you would be using x2.5 / x3 less energy for hot water than if you used the energy with a solar diverter. It won't make a huge amount of different as hot water is probably about 10% of your heat pump usage, but potentially worth thinking about... We've not got solar yet, our roof is in need of some TLC in the next few years, but maybe I would look to program the heat pump to heat water during day light hours so I can benefit from any generation. Everything better than the gas boiler I guess!! Tom
It depends. The efficency of ashp means timing it for peak sun time is more efficent than the solar diverter. Octopus exprot rate is generous too so no need to burn through the solar electricity if you don't have too.
What settings are you using for your DHW cycle? Personally i've found my efficiency is slightly better with the eco mode on the main controller but only when the offset is set low at 10k. I know energystatsuk didn't find much difference in his own use but my data is showing a larger delta so far. I wonder what offset his was set to?
Good question, I haven't played much with the DHW settings, other than taking out the legionella cycle (I tend to wait for very low prices on Octopus agile before lifting temperature particularly high). Our offset is actually set at 3k, I wonder what impact that has....? It is tricky with so many different settings in the controller to know a) what you are doing when you tinker... b) know what is the 'right' or most efficient setting We don't use eco mode... but not 100% sure why... All seems to be working ok, but maybe more to explore??! Tom
@@TomBray-LowCarbonLifestyle the offset at 3k means your HP flow temp is only 3 degrees above the cylinder probe temp. Your recharge temp may be slow with it set so low. Mine was left at 25k which gave a fast reheat time but poor efficiency. I discussed with Vaillant tech and they recommended 10-15k for a Unistor cylinder and my 7kW Arotherm Plus. The eco mode I refer to is not set on the sensocomfort controller, it is set on the white main controller, hidden in the installer menu. The eco setting on the sensocomfort only applies to gas boilers and not applicable to heat pumps 👍 Keep up all the great content and the awareness that it raises 👍
I have been wondering the same about summer use. I dont as yet have a heat pump as my gas rate is 6.6p and running my combi at a low flow. I did use the mixergy tank over summer and that gave me a big insight as to how much water we use, and its alot. 4 of us eat through 200l . Wear and tear on the heat pump is a consideration when using solar diverter as i do. Solar diverter is great if you dont have battery, but with battery's definitely good to charge and then use the higher power requirement of the heat pump. My goal is still heat pump but with 30kwh battery's. 300% + efficency and time of day tariff electricity. I think its next year though as the heat pump prices have magically risen. Can i ask who installed you'res?
Your combi boiler isn't heating a massive tank though, you'd only be paying to heat the water you use. We only used 5 units of gas last month - family of 4 with no gas cooking appliances. That's 35p last month for gas - but sadly closer to £10 once the standing charge was added. I'd like to hope heat pumps will get to a point where they can heat water on the fly too - water tanks are realistically an expensive and inefficient way of heating water when considering the amount of water actually used by the end user, and they will feel like a step backwards to a lot of people
Hi Motion Plays, just to confirm, 5 units of gas you mean 5 kWh? Or 5 m3? 5 kWh would be enough to heat 100-110 litres of mains water to 50 degrees. 100 litres would be about 11 minutes of showers. Or 5 m3, 11 times that, which is maybe more reasonable but that would be 55 kWh in a month, which is more than what I have used…? I’ve tried to put inefficiencies of my water tank into the calc on the video. Heat pumps are very unlikely to be able to heat water like a combi boiler. Partly because combi boilers are so oversized they can deliver a lot of heat very quickly. Apologies if I have misunderstood your comment! Tom
