Air Source Heat Pump
Discussion
As the person who bumped this old-ish thread yesterday, I want to say thank you to Equus and all for their knowledgable input into this.
I believe I understand the ASHP downsides, but for me, I do believe strongly in trying to reduce my fossil fuel usage. Conveniently, the government also seem to be willing to throw money at me to do so to help the capital investment case. I don't expect any monthly bill reduction, as my electricity bill will likely rise in line with my oil usage reduction.
I see this as akin to electric cars today. When compared unemotionally with an ICE car, on the basis of attributes we have come to expect from an ICE car (range, towing capacity, second hand availability & price etc.), they don't stack up. However, some changes to the way we use them can make them stack up, whilst getting the benefits of zero tailpipe emission and reduction in particulates.
I see ASHP in the same way, particularly on a 70s house like mine rather than a modern. I will have to change my behaviour to make it work, by keeping the heat level more constant, and addressing as many of the heat leaks in the house as possible.
From a pure attribute perspective, oil fired heating makes more sense than ASHP in my case. But that continues to burn 1,500l of oil a year, akin to 12k miles in the car.
Maybe I am buying the marketing bull - hook, line and sinker.....
Martin.
I believe I understand the ASHP downsides, but for me, I do believe strongly in trying to reduce my fossil fuel usage. Conveniently, the government also seem to be willing to throw money at me to do so to help the capital investment case. I don't expect any monthly bill reduction, as my electricity bill will likely rise in line with my oil usage reduction.
I see this as akin to electric cars today. When compared unemotionally with an ICE car, on the basis of attributes we have come to expect from an ICE car (range, towing capacity, second hand availability & price etc.), they don't stack up. However, some changes to the way we use them can make them stack up, whilst getting the benefits of zero tailpipe emission and reduction in particulates.
I see ASHP in the same way, particularly on a 70s house like mine rather than a modern. I will have to change my behaviour to make it work, by keeping the heat level more constant, and addressing as many of the heat leaks in the house as possible.
From a pure attribute perspective, oil fired heating makes more sense than ASHP in my case. But that continues to burn 1,500l of oil a year, akin to 12k miles in the car.
Maybe I am buying the marketing bull - hook, line and sinker.....
Martin.
Martin30 said:
As the person who bumped this old-ish thread yesterday, I want to say thank you to Equus and all for their knowledgable input into this.
I believe I understand the ASHP downsides, but for me, I do believe strongly in trying to reduce my fossil fuel usage. Conveniently, the government also seem to be willing to throw money at me to do so to help the capital investment case. I don't expect any monthly bill reduction, as my electricity bill will likely rise in line with my oil usage reduction.
I see this as akin to electric cars today. When compared unemotionally with an ICE car, on the basis of attributes we have come to expect from an ICE car (range, towing capacity, second hand availability & price etc.), they don't stack up. However, some changes to the way we use them can make them stack up, whilst getting the benefits of zero tailpipe emission and reduction in particulates.
I see ASHP in the same way, particularly on a 70s house like mine rather than a modern. I will have to change my behaviour to make it work, by keeping the heat level more constant, and addressing as many of the heat leaks in the house as possible.
From a pure attribute perspective, oil fired heating makes more sense than ASHP in my case. But that continues to burn 1,500l of oil a year, akin to 12k miles in the car.
Maybe I am buying the marketing bull - hook, line and sinker.....
Martin.
ASHP aren't as cheap to run as you may expect. I believe I understand the ASHP downsides, but for me, I do believe strongly in trying to reduce my fossil fuel usage. Conveniently, the government also seem to be willing to throw money at me to do so to help the capital investment case. I don't expect any monthly bill reduction, as my electricity bill will likely rise in line with my oil usage reduction.
I see this as akin to electric cars today. When compared unemotionally with an ICE car, on the basis of attributes we have come to expect from an ICE car (range, towing capacity, second hand availability & price etc.), they don't stack up. However, some changes to the way we use them can make them stack up, whilst getting the benefits of zero tailpipe emission and reduction in particulates.
I see ASHP in the same way, particularly on a 70s house like mine rather than a modern. I will have to change my behaviour to make it work, by keeping the heat level more constant, and addressing as many of the heat leaks in the house as possible.
From a pure attribute perspective, oil fired heating makes more sense than ASHP in my case. But that continues to burn 1,500l of oil a year, akin to 12k miles in the car.
Maybe I am buying the marketing bull - hook, line and sinker.....
Martin.
We bought an A rated passiv haus and moved in December 2013. 4 years later, despite routine on-time maintenance, the compressor crapped out. In fact, it did that about a week after it's been serviced. Service is about €450/ yr. - more than my car! It was nearly €4K to have the compressor replaced!
ASHP costs more on electricity per year than my prior oil heating did for oil AND servicing, and whilst I know my new system *should* be cleaner, most of the local electricity where I live isn't green / renewable, but bought from France and Germany - nuclear or coal based! The ASHP is also f
king noisy when it pumps out condensation from the unit.I wouldn't buy a house with one installed again, until,
A) the electricity is from renewable sources
B) they're cheaper to run / service
C) they're quieter. The noisy b
d thing!D) they're smaller. It's f
king massive!And if a padsiv Haus is more expensive to heat with a ashp than oil then trying to retrofit existing housing stock is going to be an issue
People always seem to quote these figures for running one
For every 1 kWh of electricity, an air source heat pump can produce 3kWh of heat. The average annual demand for most homes in the UK is at 12,000 kWh.
12,000 kWh (heat demand) / 3kW (heat production per unit of electricity) = 4,000 kWh of electricity
At 4,000 kWh of electricity priced at £0.13 a unit, it will cost you around £520 in annual heating costs.
That's optimal and since our climate changes it won't be those figures
People always seem to quote these figures for running one
For every 1 kWh of electricity, an air source heat pump can produce 3kWh of heat. The average annual demand for most homes in the UK is at 12,000 kWh.
12,000 kWh (heat demand) / 3kW (heat production per unit of electricity) = 4,000 kWh of electricity
At 4,000 kWh of electricity priced at £0.13 a unit, it will cost you around £520 in annual heating costs.
That's optimal and since our climate changes it won't be those figures
Edited by Trustmeimadoctor on Monday 15th February 11:33
Trustmeimadoctor said:
Most us about hydrogen but there is quite a bit about ashp
https://youtu.be/4uNKPDREa-Q
This video was very useful for me, thanks for sharing. Whilst it is just one view, and from the semi-bias of a boiler manufacturer, the content was argued well. Alas though, it has completely swayed my view that a reduced fossil burning solution is not currently possible disappointingly. https://youtu.be/4uNKPDREa-Q
The new pieces of info for me were:
- Existing microbore heating pipework diameter in the house is likely to be substandard for the water flow needed by a heat pump, and very hard to fix. This has never been mentioned by any of the installers I have spoken with.
- Clearly re-enforcing the common sense view (that I already understood, but tried to mentally get round) that ASHPs are going to be operating at their worst efficiency, when they are most needed (cold outside). That does not sit well with me as an engineer.
- There is future potential for synthetic fuels/Hydrotreated Vegetable Oil for carbon reduced alternatives to fossil oil.
Martin.
Edited by Martin30 on Monday 15th February 12:11
Why would anyone would get one of these things rather than an inverter type? As far as I can see the inverters are way better in terms of heat when you need it, cheaper and use less space while having a similar level of efficiency.
What am I missing, apart from government grants and companies keen to cash in?
What am I missing, apart from government grants and companies keen to cash in?
My place is a three bed semi new build, nothing unique insulation wise.
Monobloc inverter type heat pump running the underfloor heating via a buffer thank on both floors which are beam and block with I think 100mm screed or less.
Hot water is from another internal heat pump water heater 300lt which also acts as mechanical heat recovery ventilation.
I’m currently paying £68 a month (including charging my car once a week). Octopus GO - so in theory green energy
Monobloc inverter type heat pump running the underfloor heating via a buffer thank on both floors which are beam and block with I think 100mm screed or less.
Hot water is from another internal heat pump water heater 300lt which also acts as mechanical heat recovery ventilation.
I’m currently paying £68 a month (including charging my car once a week). Octopus GO - so in theory green energy
RC1807 said:
ASHP aren't as cheap to run as you may expect.
We bought an A rated passiv haus and moved in December 2013. 4 years later, despite routine on-time maintenance, the compressor crapped out. In fact, it did that about a week after it's been serviced. Service is about €450/ yr. - more than my car! It was nearly €4K to have the compressor replaced!
ASHP costs more on electricity per year than my prior oil heating did for oil AND servicing, and whilst I know my new system *should* be cleaner, most of the local electricity where I live isn't green / renewable, but bought from France and Germany - nuclear or coal based! The ASHP is also fking noisy when it pumps out condensation from the unit.
I wouldn't buy a house with one installed again, until,
A) the electricity is from renewable sources
B) they're cheaper to run / service
C) they're quieter. The noisy bd thing!
D) they're smaller. It's fking massive!
At 4K were you not better of replacing the monobloc ? I dont know they cost back in 2017 but 4K would just about buy you a replacement now. We bought an A rated passiv haus and moved in December 2013. 4 years later, despite routine on-time maintenance, the compressor crapped out. In fact, it did that about a week after it's been serviced. Service is about €450/ yr. - more than my car! It was nearly €4K to have the compressor replaced!
ASHP costs more on electricity per year than my prior oil heating did for oil AND servicing, and whilst I know my new system *should* be cleaner, most of the local electricity where I live isn't green / renewable, but bought from France and Germany - nuclear or coal based! The ASHP is also f
king noisy when it pumps out condensation from the unit.I wouldn't buy a house with one installed again, until,
A) the electricity is from renewable sources
B) they're cheaper to run / service
C) they're quieter. The noisy b
d thing!D) they're smaller. It's f
king massive!Edited by jymmm on Monday 15th February 13:18
Martin30 said:
I believe I understand the ASHP downsides, but for me, I do believe strongly in trying to reduce my fossil fuel usage. Conveniently, the government also seem to be willing to throw money at me to do so to help the capital investment case. I don't expect any monthly bill reduction, as my electricity bill will likely rise in line with my oil usage reduction.
I see this as akin to electric cars today.
I've looked into ASHP as part of a new build/extension on our 1960s bungalow as having an electric car has made me much more conscious of energy usage. I see this as akin to electric cars today.
But the more I looked into ASHP the more it was apparently they simply aren't viable solutions, its not just the cost, but as others have mentioned their response time/performance in temperatures we had the past week.
If you want to save energy, get a home battery storage system and solar panels, am paying 9p per kWh all day long by charging the home battery on cheap electricity overnight, and when the sun shines its free.
Also the last thing I owned which had a ASHP in it was a 2015 Nissan Leaf.......Anyone whos driven a 2015 Nissan Leaf in winter will tell you keeping warm in one is virtually impossible when temperatures drop to 0 degrees/below, infact I believe at cold temperature the Leaf switched back to a resistive heater as the ASHP in it become essentially useless.
EVs have compromises on range which these days is actually nearly gone, but ASHP from my understanding simply don't work in many situations. So expensive to install, expensive to run, and uncertain operating window meant am sticking with traditional boiler system for the build.
gangzoom said:
That maybe, but for the cost needed there are better ways to spend money for heating the house. Or indeed just upping the solar PV array.
I'd agree to be fair. ASHP when used correctly i.e with good thermal mass and good insulation and UFH work very efficiently.If fitting retrospectively then it would be the last thing in the chain after sorting insulation, UFH etc.
What are people’s thoughts on air-to-air heat pumps? My loft bedroom has a mini-split AC unit in it, and even when it’s well below zero outside, it can produce heat fairly rapidly. A five minute warmup, and from then on, a steady stream of warm air heats the room up rapidly. Mine is a fairly basic 7 year old Toshiba, and from the way it revs up the external unit, it’s definitely not using resistive heating on the internal unit (which I don’t believe it has, anyway).
Best of both worlds (for heating the house) or am I missing something? I guess it can’t do hot water, but anything else?
Best of both worlds (for heating the house) or am I missing something? I guess it can’t do hot water, but anything else?
We’ve just started the process of replacing a thermal store/log burners combo with ASHP. Our house was designed around the thermal store (which is st) and I have had a few engineers out to look at oil and ASHP. Unfortunately integrating oil into our existing setup is going to be too difficult, but is not insurmountable and would involve lots of cutting holes in nice bits of our house.
ASHP looks to be the way forward although I would admit we have some work to do over summer to make it air tight and draft proof, it’s well insulated but badly fitted windows and lots of air bricks etc mean it’s a relatively leaky house. I’m a bit confused by the RHI though as having out our EPC details into the government calculator, the Max return I would get back is £9,100 over 7 years. Both ASHP installers have come up with different numbers in the region of £11-12k RHI on a £14-16k+ installation cost. I’m pretty intrigued by it all and I think I’m going to godown the ASHP route, for nothing else other than our house is almost ready for one anyway (wet UFH and thermostats everywhere) and getting most of the installation cost repaid is very attractive too.
I dread to think what our electricity bills will be, but I intend to use it on a low setting and use our log burners as a ‘boost’. Which is basically what we have been doing for 2 years now but without the UFH working.
t) and I have had a few engineers out to look at oil and ASHP. Unfortunately integrating oil into our existing setup is going to be too difficult, but is not insurmountable and would involve lots of cutting holes in nice bits of our house.ASHP looks to be the way forward although I would admit we have some work to do over summer to make it air tight and draft proof, it’s well insulated but badly fitted windows and lots of air bricks etc mean it’s a relatively leaky house. I’m a bit confused by the RHI though as having out our EPC details into the government calculator, the Max return I would get back is £9,100 over 7 years. Both ASHP installers have come up with different numbers in the region of £11-12k RHI on a £14-16k+ installation cost. I’m pretty intrigued by it all and I think I’m going to godown the ASHP route, for nothing else other than our house is almost ready for one anyway (wet UFH and thermostats everywhere) and getting most of the installation cost repaid is very attractive too.
I dread to think what our electricity bills will be, but I intend to use it on a low setting and use our log burners as a ‘boost’. Which is basically what we have been doing for 2 years now but without the UFH working.
jymmm said:
At 4K were you not better of replacing the monobloc ? I dont know they cost back in 2017 but 4K would just about buy you a replacement now.
Genuinely, I have absolutely no idea, and this is a major reason why I dislike the contract servicing agent. Edited by jymmm on Monday 15th February 13:18
gangzoom said:
I've looked into ASHP as part of a new build/extension on our 1960s bungalow as having an electric car has made me much more conscious of energy usage.
But the more I looked into ASHP the more it was apparently they simply aren't viable solutions, its not just the cost, but as others have mentioned their response time/performance in temperatures we had the past week.
If you want to save energy, get a home battery storage system and solar panels, am paying 9p per kWh all day long by charging the home battery on cheap electricity overnight, and when the sun shines its free.
Also the last thing I owned which had a ASHP in it was a 2015 Nissan Leaf.......Anyone whos driven a 2015 Nissan Leaf in winter will tell you keeping warm in one is virtually impossible when temperatures drop to 0 degrees/below, infact I believe at cold temperature the Leaf switched back to a resistive heater as the ASHP in it become essentially useless.
EVs have compromises on range which these days is actually nearly gone, but ASHP from my understanding simply don't work in many situations. So expensive to install, expensive to run, and uncertain operating window meant am sticking with traditional boiler system for the build.
You may or may not save money having a battery installation at home, but you’re certainly not saving the planet in the slightest. You have a perfectly good grid that has had massive investment into it, and on top of that you’re racking a load of Liion cells to save a few pence a night. I doubt the ecomomics adds up either - we have a big solar installation and when I looked at batteries, the payback was of the order of decades. But the more I looked into ASHP the more it was apparently they simply aren't viable solutions, its not just the cost, but as others have mentioned their response time/performance in temperatures we had the past week.
If you want to save energy, get a home battery storage system and solar panels, am paying 9p per kWh all day long by charging the home battery on cheap electricity overnight, and when the sun shines its free.
Also the last thing I owned which had a ASHP in it was a 2015 Nissan Leaf.......Anyone whos driven a 2015 Nissan Leaf in winter will tell you keeping warm in one is virtually impossible when temperatures drop to 0 degrees/below, infact I believe at cold temperature the Leaf switched back to a resistive heater as the ASHP in it become essentially useless.
EVs have compromises on range which these days is actually nearly gone, but ASHP from my understanding simply don't work in many situations. So expensive to install, expensive to run, and uncertain operating window meant am sticking with traditional boiler system for the build.
I’ve having a new garage built (if planning works, with accommodation above) and we’ll almost certainly go ASHP because we’ll design it in from the start - the whole thing with be wet UFH on the ground floor and large panels on the upper floor. No way would I put it in the existing house.
Question I have is why bother with ASHP feeding a hydronic system? As you’ve got to replace the radiators with bigger units, why not just ditch it completely and go with the next step on from a basic heat pump; a ductless multi-zone VRF (variable refrigerant flow) system? You can control each room/zone individually, and air conditioning/humidity control is also a standard feature of such systems. Another massive benefit is that such systems can also transfer heat between zones within the home.
For example you’ve got your log burner blasting away in the lounge and overheating that room. A multi-zone vrf system can actually take that excess heat out of the lounge and transfer it into other zones, on top of the heat energy it’s already pulling from the outside air. They’ll also still run at 80% capacity down to -25C, and will remain at 100% at any temperature the UK climate can throw at it.
Maybe I’m missing something, but it seems like the obvious answer, hamstrung simply because the UK is hung up on legacy hydronic heating systems.
For example you’ve got your log burner blasting away in the lounge and overheating that room. A multi-zone vrf system can actually take that excess heat out of the lounge and transfer it into other zones, on top of the heat energy it’s already pulling from the outside air. They’ll also still run at 80% capacity down to -25C, and will remain at 100% at any temperature the UK climate can throw at it.
Maybe I’m missing something, but it seems like the obvious answer, hamstrung simply because the UK is hung up on legacy hydronic heating systems.
Edited by dvs_dave on Monday 1st March 06:21
rxe said:
You may or may not save money having a battery installation at home, but you’re certainly not saving the planet in the slightest. You have a perfectly good grid that has had massive investment into it, and on top of that you’re racking a load of Liion cells to save a few pence a night. I doubt the ecomomics adds up either - we have a big solar installation and when I looked at batteries, the payback was of the order of decades.
Whilst I agree the economics of batteries are slim, even on a Agile tariff, they do offer significant CO2 benefits if used properly. The evening peak is met by a clusters of OCGT and diesel units, often quite close to homes. ASHP owner here, 14kw mitsi unit it a 1920 non cavity wall property.
Completely the wrong install for the house IMHO. Was installed before we purchased and outdoor unit replaced day before sale. Previous unit lasted 10 years, installed price £15k, replacement cost was £6k.
I’ve seen the PO’s bills and for a 1750sqft property, the electricity bill... £4.5k pa! House was vacant for 9 months and still racked up £2.6k in elec.
There were a few issues and I’ve got it running more efficiently now... god knows how long one of the rad zone valves had been stuck open for. 2nd zone had no stat so was permanently on.
Unfortunately UF heating out of the question atm (might do when we extend)
I’ve been replacing rads with larger units, have split the system into 3 zones and installed nests.
Last month (it was cold) still managed to use £320 (can’t remember exact kwh) and that was with 2 log burners also going!
Given longevity, running cost and practicalities of insulating an older property to a high enough standard, if it went again I think I’d be looking for another solution (no main gas here)
Great watching the defrost cycle out of the office window on a cold day though
Completely the wrong install for the house IMHO. Was installed before we purchased and outdoor unit replaced day before sale. Previous unit lasted 10 years, installed price £15k, replacement cost was £6k.
I’ve seen the PO’s bills and for a 1750sqft property, the electricity bill... £4.5k pa! House was vacant for 9 months and still racked up £2.6k in elec.
There were a few issues and I’ve got it running more efficiently now... god knows how long one of the rad zone valves had been stuck open for. 2nd zone had no stat so was permanently on.
Unfortunately UF heating out of the question atm (might do when we extend)
I’ve been replacing rads with larger units, have split the system into 3 zones and installed nests.
Last month (it was cold) still managed to use £320 (can’t remember exact kwh) and that was with 2 log burners also going!
Given longevity, running cost and practicalities of insulating an older property to a high enough standard, if it went again I think I’d be looking for another solution (no main gas here)
Great watching the defrost cycle out of the office window on a cold day though
Edited by Danns on Sunday 28th February 22:28
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