Thing is most boiler or heating replacements are forced and time sensitive, its easier and cheaper to just whack in another gas boiler. Just another impediment to the mass uptake.
Heat Pumps: anyone have one/thought about it?
- Thread starter fish
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Yup and they also don’t actually do the work to make sure what they are installing is optimal for the property.
yup
although after northern power grid were messing me about for months, they sent clancy docra out as a separate job to update my cut out so a smart metre could be fitted. Their engineer took over supervision and sorted the whole job upgrading the fuses and cut outs for myself and my neighbours that are on the same loop.
Soldato
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Slight update for anyone interested.
I have a 1960s bungalow which is about 110m^2, cavity walls and suspended floor. Cavity is bead filled and when we refurbished we added 100mm insulation between floor rafters. Floor build up was 22mm Caberdek, 10mm ply, about 5mm latex screed and and then Karndean everywhere except bedrooms and lounge. Loft insulation was increased to 200mm throughout.
We used pre-insulated pipes from the manifold to new and correctly sized radiators in all rooms, with the bathroom on electric underfloor.
I have been holding the thermostat at 18 degrees 24/7 for the past few weeks. Our total usage has been circa 18kw per day with external temps on average around 5-6 degrees. 14kw of draw is from the heat pump. Unit price is 23p, with Ovo providing a rebate of 8p per unit consumed by the heat pump. The heat pump is therefore costing £2.10 per day to run, less £0.30 per day of avoided gas standing charge, bringing it to £1.80 effective.
Clearly there will be colder periods that will increase the cost, but equally there will be less usage as we move towards summer. My COP appears a bit unreliable in the Vaillant app, which is showing as 7.0, which is clearly wrong, but indicatively we seem to be about 5.0.
I have a 1960s bungalow which is about 110m^2, cavity walls and suspended floor. Cavity is bead filled and when we refurbished we added 100mm insulation between floor rafters. Floor build up was 22mm Caberdek, 10mm ply, about 5mm latex screed and and then Karndean everywhere except bedrooms and lounge. Loft insulation was increased to 200mm throughout.
We used pre-insulated pipes from the manifold to new and correctly sized radiators in all rooms, with the bathroom on electric underfloor.
I have been holding the thermostat at 18 degrees 24/7 for the past few weeks. Our total usage has been circa 18kw per day with external temps on average around 5-6 degrees. 14kw of draw is from the heat pump. Unit price is 23p, with Ovo providing a rebate of 8p per unit consumed by the heat pump. The heat pump is therefore costing £2.10 per day to run, less £0.30 per day of avoided gas standing charge, bringing it to £1.80 effective.
Clearly there will be colder periods that will increase the cost, but equally there will be less usage as we move towards summer. My COP appears a bit unreliable in the Vaillant app, which is showing as 7.0, which is clearly wrong, but indicatively we seem to be about 5.0.
My average is about 10kwh during warm weather so just hot water to 30kwh during this time of year hot water and heating with increases on very cold or damp days so you seem to be in line with me and I have mine set to 18.5°C
Saturday I went to see a client of SGS Energy, they have self built a house, but had a really rough time with the builder, who was doing everything, but the relationship fell apart prior to the heating being installed (luckily for them by the sounds of it). So they were very careful choosing an installer, they were very impressed with SGS, who by the sounds of it have given an excellent service, even helping sort issues with the PV install as the builder never completed the paperwork for that
Deposit paid, install booked for W/C 14 April.
Cost to me, just under £5k.
Deposit paid, install booked for W/C 14 April.
Cost to me, just under £5k.
You can get some monitoring kit here but it's quite pricey and I'd imagine it would be better off being professionally installed.
Is 18c warm enough for you?
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Soldato
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It feels comfortable which tells me I need a more accurate thermometer and then adjust the offset
It's been a bit of a wait, but I got my reply from the DNO this morning and they're fine with me getting a heat pump after all that! They're clearly using diversity calculations and figured quite rightly i wouldn't be having two showers, with two ovens on while charging my EV and house batteries. 
Just waiting to hear on my install date.
Just waiting to hear on my install date.
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Soldato
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Just received our latest bill with a meter reading taken 1st Jan 2025, the Heat Pump element of our bill for the last quarter was £166 - that's crazy value as far as I'm concerned, £55.33 a month to heat the whole house to 22c throughout October/November/December with a 20c setback temp between 10pm and 2pm, we're never cold.
But does highlight how much electricity we're using for everything else (too much
)
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Pulled the trigger on the Octopus install. £770, with about 8 rad changes. They’ve quoted for the Daikin 6KW unit. I need an EPC though as ours just expired.
Given the low cost I’ve shifted what I was expecting to set aside into solar and a battery. If that all goes to plan just need to consider switching from gas to induction to go fully electric.
Given the low cost I’ve shifted what I was expecting to set aside into solar and a battery. If that all goes to plan just need to consider switching from gas to induction to go fully electric.
This sounds exactly like our install with Octopus. We had an estimated heat loss of 5.39kW at -3C and was also recommended the 6kW Daikin unit. Ours was £604 all in with 8 radiator changes just like you. Ours is a new build so we already had an EPC (87 B) and that was pre-solar, so I imagine with that price they expect yours to be pretty good aswell.
Now it's all going ahead I just had an email today asking whether we want the gas capped at where the boiler is, at the meter, or the meter removed. We've gone for the full meter removal as we're also putting in an induction hob. Its only a 13A one in our case as we rarely cook on more than one or two (occasionally) rings and wiring in a 7kW supply would be a nightmare with our setup.
We should save quite a bit as our gas and standing charge bill was about £600 in 2024. We intend to heat the water cylinder and pre-heat by 05:30am during the cheap period and then coast on battery and solar when possible during the peak time. Even without that, with the 6 hours cheap rate on Intelligent Go (6p/kWh on my EV saver tariff) it gives a 24 hour average of about 20.4p. We'd have to use nearly 3000kWh a year on the heat pump and induction hob alone for it to be above break even cost.
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Is that a 6kW Daikin? What kind of usage is that from the heat pump alone?
We used 592kWh alone with the battery charging and EV in January at an average of 6.7p. We force exported over 200kWh in the evening though so could probably have got to about 800kWh in the month without much more peak usage.
Mind you, gas alone in January was £117 so there's some margin there!
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Yes, 6kw Daikin.
I've got a Shelly EM on the heat pump and that is reporting for January:
Heat pump: 589.83kwh
Immersion: 5.82kwh (1x legionella cycle per week only)
My weather compensation curve is set to 30C at 12C outside to 45C at -8C outside, this is way lower than the design temperature of 50C at -2.3. At -2 I was running 40-41C flow temps which is highly optimal IMO, house maintained 20-21C at those flow temps but it is right on the edge of my heat loss, I couldn't go any lower.
The heat pump is set to 21C from 00:00 to 21:00 and 20c from 21:00 to 00:00.
I also use home assistant and apply a +10C flow temperature offset (to maximise the cheap electric) and a +1C target temperature offset (to keep the heat pump going but not let the house get too hot) between 02:00 and 05:30.
With these settings the heat pump usually runs from about 01:00 to 05:30. It will usually shut off at 05:30 as I am above target for a period of time, that depends on how cold it is. Today it shut off for 1 hour 15 mins before kicking in again for the rest of the day and it will shut down at 21:00 until after 7p electricity time starts.
Hot water heats to 50c once per day at 03:00.
As you can tell, I don't run for maximum efficiency, I target lower costs. I used to have ESPaltherma device running on it which gathers a lot more data but I changed my router and all my local IP addresses changed and I couldn't be bothered to reprogram it and put it back into the heat pump so its sat on a shelf in my office. Now I have everything dialled in how I want it, I don't need to touch the settings, it just quietly does its thing all day every day.
Don't ask me what the SCOP is, I don't know, all I know is it costs very little to run. I'm pushing 35% off peak when its the coldest of the cold, yesterday I used 19kwh and was just under 50% off peak.
I've got a Shelly EM on the heat pump and that is reporting for January:
Heat pump: 589.83kwh
Immersion: 5.82kwh (1x legionella cycle per week only)
My weather compensation curve is set to 30C at 12C outside to 45C at -8C outside, this is way lower than the design temperature of 50C at -2.3. At -2 I was running 40-41C flow temps which is highly optimal IMO, house maintained 20-21C at those flow temps but it is right on the edge of my heat loss, I couldn't go any lower.
The heat pump is set to 21C from 00:00 to 21:00 and 20c from 21:00 to 00:00.
I also use home assistant and apply a +10C flow temperature offset (to maximise the cheap electric) and a +1C target temperature offset (to keep the heat pump going but not let the house get too hot) between 02:00 and 05:30.
With these settings the heat pump usually runs from about 01:00 to 05:30. It will usually shut off at 05:30 as I am above target for a period of time, that depends on how cold it is. Today it shut off for 1 hour 15 mins before kicking in again for the rest of the day and it will shut down at 21:00 until after 7p electricity time starts.
Hot water heats to 50c once per day at 03:00.
As you can tell, I don't run for maximum efficiency, I target lower costs. I used to have ESPaltherma device running on it which gathers a lot more data but I changed my router and all my local IP addresses changed and I couldn't be bothered to reprogram it and put it back into the heat pump so its sat on a shelf in my office. Now I have everything dialled in how I want it, I don't need to touch the settings, it just quietly does its thing all day every day.
Don't ask me what the SCOP is, I don't know, all I know is it costs very little to run. I'm pushing 35% off peak when its the coldest of the cold, yesterday I used 19kwh and was just under 50% off peak.
Just received our latest bill with a meter reading taken 1st Jan 2025, the Heat Pump element of our bill for the last quarter was £166 - that's crazy value as far as I'm concerned, £55.33 a month to heat the whole house to 22c throughout October/November/December with a 20c setback temp between 10pm and 2pm, we're never cold.
But does highlight how much electricity we're using for everything else (too much
What is your heat loss and which heatpump you got?
Everyone that I hear that has a good deal half less than half our heat loss and only 6KW heatpump. We would need minimum 11KW one so bills alone on that would be nearly double probably?
I would not even mind. It's the 7.5K they want to do the job now that puts me off.
Soldato
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It's an 11.2kw Mitsubishi Ecodan and the house is heated with wet underfloor heating throughout.
I've no idea of actual heat loss, but we've undergone extensive renovation throughout - it's a 1950s cavity bungalow where we've added PIR insulation over the whole floor (under the 50mm liquid screed wet UFH), 300mm loft insulation, 90mm external EPS wall insulation and brand new windows and doors throughout so pretty modern specs in that sense, but probably quite "leaky" due to older building practices in areas (the tops of the internal cavity walls are quite leaky!)
I've no idea of actual heat loss, but we've undergone extensive renovation throughout - it's a 1950s cavity bungalow where we've added PIR insulation over the whole floor (under the 50mm liquid screed wet UFH), 300mm loft insulation, 90mm external EPS wall insulation and brand new windows and doors throughout so pretty modern specs in that sense, but probably quite "leaky" due to older building practices in areas (the tops of the internal cavity walls are quite leaky!)
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That looks pretty promising, about 19kWh per day in what was a pretty cold month and set to 20-21C all of the time.
We generally run the house a bit cooler and intend to have it at 20C for the most part (perhaps up to 21C before 5.30am to make use of the cheap electricity) but dropping to 18C in the evening before it kicking in again overnight during the cheap time. We're still (for the moment anyway) on an electric shower, so use little hot water for much else, so will do a quick reheat every night and once a week legionella cycle like yourself. Eventually we'll get rid of it though as that itself uses a lot of power and it'll be a better shower from the cylinder.
We've about 12kWh of usable battery to play with and usually have about half of it free which at the moment I export in the evening. We already push the dishwasher and washing to the cheap period so I'm hoping we can survive on battery/solar for all but the coldest part of the year. I suppose for those extra high usage days the car might need a bit of a charge in the day.
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