That's insane I don't even know where to start. Don't they have an ESOS or at least some study up front?
Heat Pumps: anyone have one/thought about it?
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Soldato
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I don't know - we weren't involved in the sizing. If we were, it would have been much leaner and hybrid
That is the thing. The consumer is generally ignorant at the moment on heat pumps. Gas boiler replace like for like. Heatpump rely on energy company or fitting company advice? Go cheap or go big. Common sense would say get as much kW for the money as possible but it does not work like that. Enhanced common sense says get the whole system heating and hot water re-evaluated. Can you trust your quotes on that and make a decision as a generally intelligent but uninformed customer.
There seems to be a lot of semitechnical discussion on here about setups and setting up your system. This will fly over many people's heads and who would prefer something as simple and straightforward as a gas boiler to operate.
I don't trust any trade in this country further than I can throw them. I get very twitching about anything that could be expensive and cause issues down the line when its done by some cowboy who saw there was a few quid to be made by doing X. See insulation for a good example of trades being more than happy to take government money to do a **** job on houses that shouldn't have it done or that they just do a pigs ear of.
The problem with so many things is that they have always got an excuse ready when they've done a **** job.
"Yeah well you probably shouldn't have a heat pump in a house like yours"
"You just need to insulate more"
"These things only really make financial sense if you have solar" etc etc
Soldato
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I suppose you know your DHW from summer consumption, so in theory all you should need is your gas bill to size your heat pump. But we're looking at a cultural shift with HPs where we're going from many people just heating the room they're in, to heating everywhere and your house actually being quite warm.
I'm actually slightly horrified that people are getting their houses up to 21 all day - I don't want to sleep in that. The heating is off in our bedroom for a good reason!
Soldato
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Yeah must have been. Even the installation contractor was like, "we told them." But they wouldn't take the feedback on board.
But that’s dealt with via system design, the rads in the bedrooms are not big enough to get them up to 21C. You can also use the TRV to throttle the temperature if it gets too warm.
customer are ignorant but that’s why there are adverts on the TV trying educate people on boiler flow temperatures.
People like Martin Lewis are banging on about it every week, including in his prime time TV slot on ITV and it is starting to get through.
I disagree that it’s common sense to get as much Kw as possible for your money. Hardly anything as a linear efficiency curve and people know to apply this to things like cars (bigger engine = burns more fuel to do the same job).
But for whatever reason the boiler is like a magic enigma box on the wall that they feed all responsibility for. In reality, they are very basic machines and you don’t need genuine status to understand them. Likewise installers should know but many simply don’t.
As for the conversations you referenced about setting up, I think you’ve drawn the incorrect conclusion there.
Those conversations were about maximising performance, not setting up. It’s not different to overclocking a PC, it was set up perfectly well out of the box but this is a forum full of nerds and if there is 5% performance to be had from tweaking a few settings, we will do it.
Ironically, gas boilers should have all the same controls and should be tuned to a similar extent. Instead most are installed with cheap on/off controls which reduce performance, quite dramatically in some cases.
Likewise, we heat to 18.5C during the day, often dropping the thermostat to 16C if we feel warm due to solar energy through quite large windows.
At night, 9pm to when we get up the thermostat goes down to 12.5C. Currently the house rarely drops below 15C overnight. We have no damp or mould at all.
Everyone is different, when we had our gas boiler I'd have the heating set back to 16°c overnight. We'd eventually get the thick duvet out, and sometimes an additional blanket.
Now we have the temperature 20°c 24/7, and still have the thin summer duvet on. We sleep perfectly well.
I did have a night set back of a couple of degrees, but my daughter is up at 5am, so the setback was from 21:00 to 04:00, then I realised there actually no point having a set back, just run it the same temperature 24/7, no need for the heat pump to play catch up to bring the house back up to temperature.
Similar here, we just run 21C 24/7 and keep the summer duvet on. I sometimes close the TRV a bit in the bedroom if its too warm or if there might be defrosts overnight as I can hear it from that radiator. It doesn't really effect it at all. COP is still good.
Today was day 1 of my heat pump installation by Octopus.
I was supposed to be getting a 6kW white Daikin unit, but instead at 9am they delivered a 14kW black monster. Would've been a little bit of overkill for my small terrace
Eventually they did get in the right kit:
Daikin Altherma 3 M EDLA06E2V3
6kW monobloc low-temperature, single-phase 220-240V, R32 refrigerant, heating only.
Joule Stelflow 210L Indirect High Gain Slimline Unvented
210L nominal (185L rated), stainless steel, single high-gain coil, max 10 bar mains/5.5 bar working, 1 immersion, energy class C.
Heating Buffer Tank
Cordivari Volano UP GBF 25 C/4 Attacchi
26L (rated 25L), 4 connections, max 6 bar/95°C, energy class B, wall-mount, for heat pump hydraulic separation/buffer.
Potable Expansion Tank
Global Water Solutions ThermoWave TWOSWH-18LH
18L horizontal, max 10 bar/150 psi, 90°C.
Magnetic System Filter
Sentinel Eliminator Vortex 700
The hardware is on the budget side. Daikin Altherma 4 with R290 will start selling in UK from January 2026 - probably quieter, with higher SCOP and capable of heating hot water to higher temp. The water cylinder is only C rated and my cupboard has enough space for a regular non-slimline cylinder - don't know why they decided to go with a slimline, that has higher heat loss. The survey may have ended with wrong measurements.
The install should be done by end of Thursday, I'll keep you updated
I was supposed to be getting a 6kW white Daikin unit, but instead at 9am they delivered a 14kW black monster. Would've been a little bit of overkill for my small terrace
Eventually they did get in the right kit:
Daikin Altherma 3 M EDLA06E2V3
6kW monobloc low-temperature, single-phase 220-240V, R32 refrigerant, heating only.
Joule Stelflow 210L Indirect High Gain Slimline Unvented
210L nominal (185L rated), stainless steel, single high-gain coil, max 10 bar mains/5.5 bar working, 1 immersion, energy class C.
Heating Buffer Tank
Cordivari Volano UP GBF 25 C/4 Attacchi
26L (rated 25L), 4 connections, max 6 bar/95°C, energy class B, wall-mount, for heat pump hydraulic separation/buffer.
Potable Expansion Tank
Global Water Solutions ThermoWave TWOSWH-18LH
18L horizontal, max 10 bar/150 psi, 90°C.
Magnetic System Filter
Sentinel Eliminator Vortex 700
The hardware is on the budget side. Daikin Altherma 4 with R290 will start selling in UK from January 2026 - probably quieter, with higher SCOP and capable of heating hot water to higher temp. The water cylinder is only C rated and my cupboard has enough space for a regular non-slimline cylinder - don't know why they decided to go with a slimline, that has higher heat loss. The survey may have ended with wrong measurements.
The install should be done by end of Thursday, I'll keep you updated
Heating Buffer Tank
Cordivari Volano UP GBF 25 C/4 Attacchi
26L (rated 25L), 4 connections, max 6 bar/95°C, energy class B, wall-mount, for heat pump hydraulic separation/buffer.
The hardware is on the budget side. Daikin Altherma 4 with R290 will start selling in UK from January 2026 - probably quieter, with higher SCOP and capable of heating hot water to higher temp. The water cylinder is only C rated and my cupboard has enough space for a regular non-slimline cylinder - don't know why they decided to go with a slimline, that has higher heat loss. The survey may have ended with wrong measurements.
The install should be done by end of Thursday, I'll keep you updated
Buffer should be installed as a volumiser with only 2 ports connected same as my Octopus install. My slimline DHW cylinder installed in the loft only loses 4-5C overnight near zero so in the house wouldn't make much difference and will probably make the installers job easier
Would be nice to have the latest R290 kit but if you only use the heat pump for say 3 or 4 of the coldest months (for heating) then the R32 units are as good or better in the coldest months and you may find you only heat your water to 50C or less most of the time and 55-60C for the legionella cycle. First thing I disabled and with low usage I only need my water at 46C with a 42C ECO setting just in case it drops that low.
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That's pretty much exactly the equipment I got too. I have the slimline tank in a cupboard but Ill be getting them to take a look at it when I have my annual service in April as I heat to 48C at midnight and by 8pm its already down to 40C for some reason. I suspect something is passing and letting cold water in. Its nothing urgent though as we don't use a lot of hot water.Today was day 1 of my heat pump installation by Octopus.
I was supposed to be getting a 6kW white Daikin unit, but instead at 9am they delivered a 14kW black monster. Would've been a little bit of overkill for my small terrace
Eventually they did get in the right kit:
Daikin Altherma 3 M EDLA06E2V3
6kW monobloc low-temperature, single-phase 220-240V, R32 refrigerant, heating only.
Joule Stelflow 210L Indirect High Gain Slimline Unvented
210L nominal (185L rated), stainless steel, single high-gain coil, max 10 bar mains/5.5 bar working, 1 immersion, energy class C.
Heating Buffer Tank
Cordivari Volano UP GBF 25 C/4 Attacchi
26L (rated 25L), 4 connections, max 6 bar/95°C, energy class B, wall-mount, for heat pump hydraulic separation/buffer.
Potable Expansion Tank
Global Water Solutions ThermoWave TWOSWH-18LH
18L horizontal, max 10 bar/150 psi, 90°C.
Magnetic System Filter
Sentinel Eliminator Vortex 700
The hardware is on the budget side. Daikin Altherma 4 with R290 will start selling in UK from January 2026 - probably quieter, with higher SCOP and capable of heating hot water to higher temp. The water cylinder is only C rated and my cupboard has enough space for a regular non-slimline cylinder - don't know why they decided to go with a slimline, that has higher heat loss. The survey may have ended with wrong measurements.
The install should be done by end of Thursday, I'll keep you updated
Apart from that its all good. You will almost certainly want to tweak the weather curve settings as Octopus' default settings are very conservative . It is at least a good time of year for them to set everything up, so yours might be a lot better.
Associate
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coldest we’ve had is -8 overnight so far this year. Grant r32 13KW with external volumiser/3KW backup handled it with aplomb. We’ve had maybe 12 sub zero nights in total but the whole house has been at 21 degrees when getting up at 7am.
Yes it’s costs money in winter but with the 7p per KW overnight rate it’s not really an issue.
People need to consider it over the whole year. Summer costs pretty much nothing, spring and autumn cost a bit and winter costs a lot.
I don’t know why that guy in the video is getting his knickers in a twist.
Yes it’s costs money in winter but with the 7p per KW overnight rate it’s not really an issue.
People need to consider it over the whole year. Summer costs pretty much nothing, spring and autumn cost a bit and winter costs a lot.
I don’t know why that guy in the video is getting his knickers in a twist.
I'd think that's perfectly normal, but would be interesting if someone with a similar size (200L) cylinder can confirm or deny.
Assuming they mean 8am not 8pm that would be normal, sounds like the 3 way value is passing water though the hot water loop when in heating mode.
The only other reason it would take heat from hot water because there wasn’t enough heat in the CH circuit to defrost the unit so it takes it from the HW as a last resort. How cold was it on Monday night into Tuesday?
The only other reason it would take heat from hot water because there wasn’t enough heat in the CH circuit to defrost the unit so it takes it from the HW as a last resort. How cold was it on Monday night into Tuesday?
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I have a 200L slimline tank and mine loses about 10C over 24h, give or take, so nearly the same over 12h does seem a bit fast. They never live up to the sticker heat loss njmbers because at the very best those are done in a lab not in a cold loft but I suspect they're just theoretical modelled numbers with not a lot of rigour.