Air Source Heat Pumps
Discussion
I’m getting quotes on the above at the moment.
An 11KW double fan Mitsubishi system is around £13K, the govt incentives to fit the unit make the payback around 10 years.
The outside unit is huge, half the size of a double bed and needs to be placed on the patio. It needs to be a twin fan unit to cope with the energy demands of the house.
Various sales spiel has been given, (about fully removing gas as a fuel to my house etc) but I wanted to check if anyway had any pro’s or cons from experience on adopting air source.
The RHI scheme is about to change (I expect for the worse) which may kill this dead anyway.
Electricity is 5X the cost of gas but air source gives 3KW of heat benefit for every 1KW of input electricity, plus electricity is more of a secure fuel source moving forward.
I am amazed at some of the rubbish I’ve been told by those looking for an order but the principal of the technology is very attractive.
Any thoughts welcome.....
An 11KW double fan Mitsubishi system is around £13K, the govt incentives to fit the unit make the payback around 10 years.
The outside unit is huge, half the size of a double bed and needs to be placed on the patio. It needs to be a twin fan unit to cope with the energy demands of the house.
Various sales spiel has been given, (about fully removing gas as a fuel to my house etc) but I wanted to check if anyway had any pro’s or cons from experience on adopting air source.
The RHI scheme is about to change (I expect for the worse) which may kill this dead anyway.
Electricity is 5X the cost of gas but air source gives 3KW of heat benefit for every 1KW of input electricity, plus electricity is more of a secure fuel source moving forward.
I am amazed at some of the rubbish I’ve been told by those looking for an order but the principal of the technology is very attractive.
Any thoughts welcome.....
Temperature is the issue with ASHP.
So if you're going to run water from it then you'll probably not get it particularly hot.
Radiators need to be a lot bigger, or underfloor heating is a good option.
Personally I'd love to get Water Sourced Heat Pump but I'm going to need a bit of land first...
So if you're going to run water from it then you'll probably not get it particularly hot.
Radiators need to be a lot bigger, or underfloor heating is a good option.
Personally I'd love to get Water Sourced Heat Pump but I'm going to need a bit of land first...
Part of the refit involves changing standard radiators for either bulky 3X core types or much larger double core types in place of current ones using elbow joints to join up the existing pipes (saving ripping floors up).
Bathrooms are exempted as not habitable rooms. 13mm bore, if your on microbore it needs replacing with 13mm.
Had warnings that you run it different to standard gas, it always needs to be on and does not run as hot. Biggest complaint is cold houses where people switch on and off for example, which is not how you run the ASHP system, low energy acheived only through constant running etc but noted on comment above.
House is assessed and measured for energy use and has to meet certain efficiency criteria to qualify (so that heat generated is not wasted).
Sales just want a sale, despite 2 visits still asking if I do or don’t have solar, no marks for attention to detail or my confidence in some of other claims made.
Govt offering £10K over 7 years to fit it though obviously appeals.
Bathrooms are exempted as not habitable rooms. 13mm bore, if your on microbore it needs replacing with 13mm.
Had warnings that you run it different to standard gas, it always needs to be on and does not run as hot. Biggest complaint is cold houses where people switch on and off for example, which is not how you run the ASHP system, low energy acheived only through constant running etc but noted on comment above.
House is assessed and measured for energy use and has to meet certain efficiency criteria to qualify (so that heat generated is not wasted).
Sales just want a sale, despite 2 visits still asking if I do or don’t have solar, no marks for attention to detail or my confidence in some of other claims made.
Govt offering £10K over 7 years to fit it though obviously appeals.
Water heating is a bone of contention with both companies that quoted. My solar PV heats a pressurised cylinder, we use no gas (other than cooking) between May and Oct.
So the gas use is loaded in winter.
So both sales people have seriously stated I only use gas half the year ‘so we can divide what you pay by 2 to give the true figure of use.’
Er, no.
In terms of noise, regs state 1M from neighbour boundary for siting. I get on with my neighbours so that won’t be happening. Luckily went to see one in operation and even though indoors, was a shock regarding noise.
Plus point was it sucked heat out of the room so you can see it working in real world.
Mitsubishi have water as transfer liquid meaning it should be cheaper to own the system.
Issue is, long after the installers disappear, I have to make sure this system works for my family and there is an air of double glazing sales about the whole thing, cold calling, incomplete info etc.....
So the gas use is loaded in winter.
So both sales people have seriously stated I only use gas half the year ‘so we can divide what you pay by 2 to give the true figure of use.’
Er, no.
In terms of noise, regs state 1M from neighbour boundary for siting. I get on with my neighbours so that won’t be happening. Luckily went to see one in operation and even though indoors, was a shock regarding noise.
Plus point was it sucked heat out of the room so you can see it working in real world.
Mitsubishi have water as transfer liquid meaning it should be cheaper to own the system.
Issue is, long after the installers disappear, I have to make sure this system works for my family and there is an air of double glazing sales about the whole thing, cold calling, incomplete info etc.....
miniman said:
Can't help but watching with interest as we have ASHP in our village hall and it is utterly useless. Which may or may not be the technology itself.
I did some research into ASHPs for our village hall and read a paper by the Scottish Government on the 'success' of all their supported projects. The stats for village halls and other occasional use buildings were terrible. The nature of ASHPs means that they are at their best when supplying low heat at a constant rate to well insulated and sealed buildings which are in almost constant use. They at their worst when heating old draughty buildings on an occasional basis. Guess which best describes a typical village hall?
We didn't go with an ASHP for the hall but I've successfully installed a few in new well insulated private homes. They are particularity good for households where there is someone at home most of the day and far less so if the occupiers are out most of the time and only come home to sleep.
Absolutely fantastic for the elderly, less so for a young family who come and go a lot unless you don't mind heating an empty house.
I'm currently fitting one (combined with underfloor heating ) in my new house which is super insulated.
Fuel saving is only £100 per year, just checked on calcs, so marginal. New system can accept direct PV feed so solar heating of hot water stays as is, concerned it may not be as hot tbh though on pure air source.
Govt give £11.5K incentive over 7 years not the figure I have above.
Hence 10 years to payback.
One of drivers for me is electricity has a good mix of sources, gas seems to be heading towards a footnote as a political football (maybe the real reason for those incentives).
I’d probably get £800 for the current boiler and cylinder, would have to loan the cash to cover the cost so 3% adds another chunk to payback.
May paint the external unit matt black and pretend I’m doing a remake of 2001......
Govt give £11.5K incentive over 7 years not the figure I have above.
Hence 10 years to payback.
One of drivers for me is electricity has a good mix of sources, gas seems to be heading towards a footnote as a political football (maybe the real reason for those incentives).
I’d probably get £800 for the current boiler and cylinder, would have to loan the cash to cover the cost so 3% adds another chunk to payback.
May paint the external unit matt black and pretend I’m doing a remake of 2001......
996Type said:
Govt give £11.5K incentive over 7 years not the figure I have above.
Hence 10 years to payback.
The RHI on a domestic property stops after 7 years so after that you'll have to rely on fuel savings for payback, so 10 years isn't realistic.
would have to loan the cash to cover the cost so 3% adds another chunk to payback.
Don't know where you are, but here in Scotland you can get an interest free loan to pay for it via Green Energy Scotland, and pay it back via the RHI. Probably something similar in the rest of the UK.
Hence 10 years to payback.
The RHI on a domestic property stops after 7 years so after that you'll have to rely on fuel savings for payback, so 10 years isn't realistic.
would have to loan the cash to cover the cost so 3% adds another chunk to payback.
Don't know where you are, but here in Scotland you can get an interest free loan to pay for it via Green Energy Scotland, and pay it back via the RHI. Probably something similar in the rest of the UK.
Seems like alot of messing around if you have mains gas, and alot of assumptions about how the system will work.
I've read alot about them not performing or achieving their cop in the real world.
Also heard about them having heater element pulsing away KW"s to achieve the flow temp in adverse cold weather, sending bills sky high.
What max flow temps have they quoted?
If you need a double stack ashp that's telling me your house isn't overly tight or efficient.
I've read alot about them not performing or achieving their cop in the real world.
Also heard about them having heater element pulsing away KW"s to achieve the flow temp in adverse cold weather, sending bills sky high.
What max flow temps have they quoted?
If you need a double stack ashp that's telling me your house isn't overly tight or efficient.
Our house has an ASHP. It’s a Mitsubishi system but not sure of the specific details. We also have solar panels. The house is c2000 sq ft. The downstairs has underfloor heating and one wood burner. Upstairs has radiators in each room and underfloor heating in bathrooms.
Not sure what information you are looking for but having lived with it for a year I have found it heats our water and home to a satisfactory level. It is a new build home so well insulated and I guess that means the radiators don’t have to get very hot (which they don’t) to keep the house warm. Water gets warm enough but not really hot. This does mean an immersion heater has to be used to ensure there is no chance of legionnaires disease.
The main downside is the very noisy outdoor unit (especially when it gets v cold outside)and my electric usage does seem high.
Happy to answer any questions if I can.
Not sure what information you are looking for but having lived with it for a year I have found it heats our water and home to a satisfactory level. It is a new build home so well insulated and I guess that means the radiators don’t have to get very hot (which they don’t) to keep the house warm. Water gets warm enough but not really hot. This does mean an immersion heater has to be used to ensure there is no chance of legionnaires disease.
The main downside is the very noisy outdoor unit (especially when it gets v cold outside)and my electric usage does seem high.
Happy to answer any questions if I can.
Sounds like a Mitsi Ecodan system. They will be running balls out this time of year and will struggle to keep the head pressure up as this is what gives you the warmth in layman terms. Two fans, defrost cycles every 20-30mins maybe a little longer compressor running hard to build head poor thing will be bouncing around like a Duracell bunny.
Would I fit one? Maybe but I’d run one solely as warm air and forgo trying to do hot water aswell as the poster above mentioned you’ll still need an immersion heater to boost the water up during prolonged cold spells.
Would I fit one? Maybe but I’d run one solely as warm air and forgo trying to do hot water aswell as the poster above mentioned you’ll still need an immersion heater to boost the water up during prolonged cold spells.
shady lee said:
Seems like alot of messing around if you have mains gas, and alot of assumptions about how the system will work.
I've read alot about them not performing or achieving their cop in the real world.
Also heard about them having heater element pulsing away KW"s to achieve the flow temp in adverse cold weather, sending bills sky high.
What max flow temps have they quoted?
If you need a double stack ashp that's telling me your house isn't overly tight or efficient.
Apologies just seen this as well,I've read alot about them not performing or achieving their cop in the real world.
Also heard about them having heater element pulsing away KW"s to achieve the flow temp in adverse cold weather, sending bills sky high.
What max flow temps have they quoted?
If you need a double stack ashp that's telling me your house isn't overly tight or efficient.
R134a ASHP needed to keep a 5000ltr buffer vessel above 39 degrees to have any chance of starting up and not falling over on LP with an OAT of around +2 degrees. Once running and building heat it supplied LTHW upto 48.5 degrees right down to -18 degrees. Supplying AHU’s, underfloor heating and fan coils in and office space. This was a 800kw machine mind but theory is the same.
R410a machine running in Chiswick caused us nothing but grief splitting condenser coils however this is down to it being able to 48 degrees LTHW and 8 degrees CHW at the same time.
I've fitted a couple of Daikin monoblock ASHPs running on R410 which work very effectively, I think the comments about running the system 24/7 to maintain temps are probably more relevant if you have ufh, oversized rads should respond reasonably quickly if correctly sized.
Been out of the loop for some time, but the rhi used to only be available if you weren't connected to mains gas, which I think the op is.
In short, if I was installing into a new build or replacing a shagged heating system I'd go for ASHP (or ground source if I could afford it), but there's no way I would rip out a perfectly good heating system to "upgrade"
Been out of the loop for some time, but the rhi used to only be available if you weren't connected to mains gas, which I think the op is.
In short, if I was installing into a new build or replacing a shagged heating system I'd go for ASHP (or ground source if I could afford it), but there's no way I would rip out a perfectly good heating system to "upgrade"
There’s some misinformation in this thread IMO. We’ve just hit 3 years with our 7.5kw Ecodan.
Still, right now if you have mains gas you’d be crazy to change, apart from anything else £11.5k return from RHI means you are heating a massive house or it’s very poorly insulated (or someone is fiddling the calcs?
) in our 1880 house we get about £3.5k over 7 years.
I would always (and did) choose a split system rather than a water based all in one, even in the recent -9 weather it worked fine, including heating our DHW to 60deg occasionally on the legionella cycle, heating a 210l tank takes about 30mins.
They are noisy, especially if you live in a quiet area - to be honest that’s my biggest issue with ours so I set it right back at night and it doesn’t come on. The heat pump itself has been reliable but I do worry what happens if it breaks down, servicing every year is required to keep up the warranty and it’s £250 or so.
But vs lpg, oil or even biomass I’d still choose it again.
(I was quoted £18k to have mains gas put in, if the other 3 neighbours had agreed that’s £4.5k each and I would’ve done it.)
/d
Still, right now if you have mains gas you’d be crazy to change, apart from anything else £11.5k return from RHI means you are heating a massive house or it’s very poorly insulated (or someone is fiddling the calcs?
) in our 1880 house we get about £3.5k over 7 years.I would always (and did) choose a split system rather than a water based all in one, even in the recent -9 weather it worked fine, including heating our DHW to 60deg occasionally on the legionella cycle, heating a 210l tank takes about 30mins.
They are noisy, especially if you live in a quiet area - to be honest that’s my biggest issue with ours so I set it right back at night and it doesn’t come on. The heat pump itself has been reliable but I do worry what happens if it breaks down, servicing every year is required to keep up the warranty and it’s £250 or so.
But vs lpg, oil or even biomass I’d still choose it again.
(I was quoted £18k to have mains gas put in, if the other 3 neighbours had agreed that’s £4.5k each and I would’ve done it.)
/d
Not sure about other manufacturers but the Daikin has a low noise mode, the compressor and fans are speed controlled, in this mode the maximum speed is limited which reduces noise (which is mostly from the fan). Only drawback is that heating capacity is also reduced in this mode, but it is quite useful in the summer when neighbours may have windows open and you just need DHW.
Servicing is really diy unless something goes wrong, brush and hoover the heat exchanger and clean the water strainer.
Servicing is really diy unless something goes wrong, brush and hoover the heat exchanger and clean the water strainer.
We have a Daikin ASHP system in our new build as there is no Gas mains.
It runs everything, heating, hot water etc.. So we only pay for electricity and are around £100 month for a 3 bed house, 2 bathrooms, U/F heating downstairs and radiators in every room upstairs.
Have no complaints really, water is very hot and the radiators and U/F heating is fine...if anything gets too warm sometimes.
The 2 machines on the wall outside are maybe the size of a single bed, slightly smaller but arn't in the way but can make a bit of noise when both on and we are sitting outside.
It runs everything, heating, hot water etc.. So we only pay for electricity and are around £100 month for a 3 bed house, 2 bathrooms, U/F heating downstairs and radiators in every room upstairs.
Have no complaints really, water is very hot and the radiators and U/F heating is fine...if anything gets too warm sometimes.
The 2 machines on the wall outside are maybe the size of a single bed, slightly smaller but arn't in the way but can make a bit of noise when both on and we are sitting outside.
AbzGuyGTI said:
We have a Daikin ASHP system in our new build as there is no Gas mains.
It runs everything, heating, hot water etc.. So we only pay for electricity and are around £100 month for a 3 bed house, 2 bathrooms, U/F heating downstairs and radiators in every room upstairs.
Have no complaints really, water is very hot and the radiators and U/F heating is fine...if anything gets too warm sometimes.
The 2 machines on the wall outside are maybe the size of a single bed, slightly smaller but arn't in the way but can make a bit of noise when both on and we are sitting outside.
See this is where I don't see the savings, we have a 3 bed house, 3 of us showering every day, heating on twice a day as needed and tumble dryer on the go most days, gas and electric bill has never been over £100.It runs everything, heating, hot water etc.. So we only pay for electricity and are around £100 month for a 3 bed house, 2 bathrooms, U/F heating downstairs and radiators in every room upstairs.
Have no complaints really, water is very hot and the radiators and U/F heating is fine...if anything gets too warm sometimes.
The 2 machines on the wall outside are maybe the size of a single bed, slightly smaller but arn't in the way but can make a bit of noise when both on and we are sitting outside.
Where is the saving if you have mains gas?
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