Air-source heat pumps - are they good/crap?
Discussion
loudlashadjuster said:
A friend has a house built a few years before mine, and his is configured to heat/cool. It works very effectively, in fact.
As with ufh heating, the cooling is subtle (don't want condensation, after all!) but the floors are all cool to the touch in summer and it makes a big difference when the outside temps have been above 25C for a week or so as you don't get any heat build-up.
I don't quite get this bit. Air to Air is simple but its not a very good way to warm a house compared to UFH. So its possible to run under floor heating pipes at low temperatures to absorb heat from the air, and the same with radiators? As with ufh heating, the cooling is subtle (don't want condensation, after all!) but the floors are all cool to the touch in summer and it makes a big difference when the outside temps have been above 25C for a week or so as you don't get any heat build-up.
I've never seen or experienced it, be interesting to hear how it all works?
Jambo85 said:
I acknowledged the up front cost in my post, no argument there. I don't agree that your assumptions are all insanely generous - heating will be far more than half of your electricity use in January, unless you're cooking loads, in the shower all the time and have your house at 10 degC.
Possibly we'll start to see some of this reflected in house valuations if energy prices continue to rise and somehow the electricity and gas prices become decoupled, and there's also no doubt in my mind that a well installed central heating system (ASHP or otherwise) is going to make a house more desirable than resistive heaters of whatever type, before you even consider running costs.
Yes, quite a lot of showers, cooking, washing so even in summer bills average a bit over £100, and more typical winter bills are £200ish. Plus a good bit of heat from a large stove.Possibly we'll start to see some of this reflected in house valuations if energy prices continue to rise and somehow the electricity and gas prices become decoupled, and there's also no doubt in my mind that a well installed central heating system (ASHP or otherwise) is going to make a house more desirable than resistive heaters of whatever type, before you even consider running costs.
It will be interesting to see how it plays out with house prices, but a bit speculative at this stage. A decent gas or oil system still seems a better bet to me without getting into speculation about things that may not happen.
Maybe a better way to look at the question is tackle insulation first. Look at what it would cost to bring your house up to the recommended specs for a heat pump, do it, then reassess if a heat pump is the best heating system.
gangzoom said:
loudlashadjuster said:
A friend has a house built a few years before mine, and his is configured to heat/cool. It works very effectively, in fact.
As with ufh heating, the cooling is subtle (don't want condensation, after all!) but the floors are all cool to the touch in summer and it makes a big difference when the outside temps have been above 25C for a week or so as you don't get any heat build-up.
I don't quite get this bit. Air to Air is simple but its not a very good way to warm a house compared to UFH. So its possible to run under floor heating pipes at low temperatures to absorb heat from the air, and the same with radiators? As with ufh heating, the cooling is subtle (don't want condensation, after all!) but the floors are all cool to the touch in summer and it makes a big difference when the outside temps have been above 25C for a week or so as you don't get any heat build-up.
I've never seen or experienced it, be interesting to hear how it all works?
I assume it just circulates water a few degrees cooler than the room temp (mine seems have a limit of -4C cooler, according to the installation guide) and dumps the heat outside. It can obviously only do one thing at a time, so if the system calls for DHW then it needs to switch into 'heat mode'. It's all transparent to the user though, seems to manage it very well.
loudlashadjuster said:
mine seems have a limit of -4C cooler, according to the installation guide...
That is logical: from memory, normal condensation risk calculations are programmed to flag a risk of surface condensation (as opposed to interstitial condensation) when they calculate the surface temperature of the internal face of a thermal element to be 5C or more cooler than the internal air temperature.loudlashadjuster said:
gangzoom said:
loudlashadjuster said:
A friend has a house built a few years before mine, and his is configured to heat/cool. It works very effectively, in fact.
As with ufh heating, the cooling is subtle (don't want condensation, after all!) but the floors are all cool to the touch in summer and it makes a big difference when the outside temps have been above 25C for a week or so as you don't get any heat build-up.
I don't quite get this bit. Air to Air is simple but its not a very good way to warm a house compared to UFH. So its possible to run under floor heating pipes at low temperatures to absorb heat from the air, and the same with radiators? As with ufh heating, the cooling is subtle (don't want condensation, after all!) but the floors are all cool to the touch in summer and it makes a big difference when the outside temps have been above 25C for a week or so as you don't get any heat build-up.
I've never seen or experienced it, be interesting to hear how it all works?
I assume it just circulates water a few degrees cooler than the room temp (mine seems have a limit of -4C cooler, according to the installation guide) and dumps the heat outside. It can obviously only do one thing at a time, so if the system calls for DHW then it needs to switch into 'heat mode'. It's all transparent to the user though, seems to manage it very well.
JuanCarlosFandango said:
It will be interesting to see how it plays out with house prices, but a bit speculative at this stage.
My prediction is that the EPC rating will be rejigged to show your house as EPC Z if you don't have a heat pump. I also would not be at all surprised if a law is introduced to basically prevent you from selling your house to a private individual if it doesn't have one, or doesn't meet a certain EPC level. For those who need to sell but can't afford or don't want to make the changes needed to achieve the required EPC rating, an NGO will probably exist by that point solely for the purpose of buying your property from you, for approx 10% of its actual value, to do you a favour.r3g said:
My prediction is that the EPC rating will be rejigged to show your house as EPC Z if you don't have a heat pump. I also would not be at all surprised if a law is introduced to basically prevent you from selling your house to a private individual if it doesn't have one, or doesn't meet a certain EPC level. For those who need to sell but can't afford or don't want to make the changes needed to achieve the required EPC rating, an NGO will probably exist by that point solely for the purpose of buying your property from you, for approx 10% of its actual value, to do you a favour.
According to a solicitor/estate agent friend of mine a heat pump instead of the normal oil boiler is very definitely not a selling point for now here in Aberdeenshire. While that will undoubtedly change in decades to come, even the most optimistic targets set by the government are nothing to worry about if you're currently needing to replace a gas boiler.
In ten or fifteen years time, heat pump technology will likely have improved (marginally) and prices will have dropped (hopefully significantly) so it's not like you're losing out. If you do have a burning desire to spend some money now - spend it on insulation.
In ten or fifteen years time, heat pump technology will likely have improved (marginally) and prices will have dropped (hopefully significantly) so it's not like you're losing out. If you do have a burning desire to spend some money now - spend it on insulation.
Equus said:
OutInTheShed said:
I'm not sure it will be political suicide to raise gas prices.
Then I suggest you don't seek a career in politics: the current shower are hardly likely to be re-elected in any case, but a tax to give a 100% increase in domestic gas prices, overnight (which is what it would take to properly incentivise a mass change to heat pumps) would probably cause rioting in the streets.OutInTheShed said:
Once consumers start switching to heatpumps en masse...
Ah, so all we need do is keep an eye out for the flying pigs, then?Heat pump installs increased 40% last year in the UK, prices are coming down, costs of boilers is going up.
Nothing is going to happen overnight, but a lot of long term gov't policy is baked-in and will be hard to change, even if there was a will to do so.
Then there's the comedy element of gov't commitment to hydrogen blended with mains gas.
So much of this 'govmint' stuff seems to be decided by people who don't need to be elected.
otolith said:
What is faintly irritating is that there appear to be loads of grants for things, but I personally qualify for absolutely f
k all to improve my insulation.
Whilst I agree with in part with your statement - sometimes you shouldn't need grants to do things that actually give you a return on investment.........k all to improve my insulation. I ordered £1000 of 75mm PIR insulation back in 2022 when Gas prices were going thro the roof
And then had the horrible job over three months of spending weekends underneath my floor in a 2 - 3 ft crawl space fitting cut down sections between the floor joist
I spent £150 on 100 metres of pipe lagging (for 22mm and 15mm copper pipes which run round my house) and lagged the crap out of all the pipes I could get at
Comparison of old and new pipe insulation (Small stuff is std DIY shop stuff)
A lot of pipes in the underfloor area were lagged in horsehair wrap which dated to the original build in the early 80's
Buying a tool to help you get really good joints is included in the cost
Since then I've spent nearly £1000 on T22 rads to replace existing T11's of the same size in order to lower my flow temp on the boiler so it actually condenses (dropping my flow temp from 70 deg in 2021 to now high 40's low 50's)
Payback on the insulation, lagging and rad upgrades should be inside 4 years - probably closer to 3 than 4. Had Gas prices gone the way it was predicted it would have been an even shorter payback.
I wasn't eligible for a grant for any of it but the difference it's made to the house temps and gas usage has made it worthwhile. (gas consumption reduced from 17,000 kW per year to 8,000 kW per year)
monkfish1 said:
Cheib said:
I’m currently considering an ASHP for a period property…we’ve just had new double glazed windows installed. External doors are either being professionally draft proofed or replaced. A couple of rooms which are colder will be getting internally insulated. We need to do all that regardless of whether we go with ASHP or Gas Boiler or a hybrid system (it’s a big house).
There’s some good advice on here OP. The things I would ask are
- Who specified the heat pump
-Ask to see those calculations
-What other work was done when the heat pump was installed. Rads and possibly larger bore pipes may have been needed. Any insulation ?
-What CoP is the heat pump currently working at. An average of 3 is about right across the year.
The main driver for us looking at one is that we’re getting a fairly large ground mounted solar system with batteries. That potentially means we won’t be buying electricity for half the year and when we do it will be overnight on a tariff of below 10p kWh.
My personal view is as well as throwing subsidies at the problem we’re going to see a change in the pricing differential for electric and gas to make the former more attractive for heating the home. It is only going to get relatively more expensive to heat your home burning gas.
Are you able to give an indication of total costs of all that work? And size of house to give some perspective?There’s some good advice on here OP. The things I would ask are
- Who specified the heat pump
-Ask to see those calculations
-What other work was done when the heat pump was installed. Rads and possibly larger bore pipes may have been needed. Any insulation ?
-What CoP is the heat pump currently working at. An average of 3 is about right across the year.
The main driver for us looking at one is that we’re getting a fairly large ground mounted solar system with batteries. That potentially means we won’t be buying electricity for half the year and when we do it will be overnight on a tariff of below 10p kWh.
My personal view is as well as throwing subsidies at the problem we’re going to see a change in the pricing differential for electric and gas to make the former more attractive for heating the home. It is only going to get relatively more expensive to heat your home burning gas.
Ive done some rough work for mine, Half period stone, half 70's cavity wall. Even doing all the work myself, i think its £35-45K all in. And its only a small place. Not factored in that we will need to move out as well.
Just curious how you make it work? I can buy a lot of oil for £40k
The double glazing and insulation needs doing anyway….roof is relatively cheap, windows very expensive.
We’re having to re-plumb the heating system regardless of whether it is an ASHP or Gas Boiler. We currently have a single pipe central heating system which is incredibly inefficient….so even if we stayed with gas we would really need to do that work. The good news is if we go with ASHP all that replacemnt upgrade work on the heating system is VAT free so that’s a decent saving.
I hear your point about heating oil/£40k but I reckon we’ll be in this house for ten years. I think the pricing differential for houses with shall we call them “legacy” heating systems in ten years time will be tangible…at least in the case of our house because it’s 6000 sq ft. So efficient heating will make a big difference.
Tom8 said:
Gas will be cheap again next year following deal with US. Broker forecasts look very favourable.
The price of electricity in this country is set off the cost of burning gas to generate electricity….a lot of the electricity is produced at much cheaper rates. There is plenty of room for electricity prices to come down significantly…if the Govt stepped in and said they will subsidise electricity generated by gas then the price of electricity would come down. That isn’t as daft as it sounds as it is the fault of Central Govt that we didn’t build nuclear power plants in this country for decades.Cheib said:
The price of electricity in this country is set off the cost of burning gas to generate electricity….a lot of the electricity is produced at much cheaper rates. There is plenty of room for electricity prices to come down significantly…if the Govt stepped in and said they will subsidise electricity generated by gas then the price of electricity would come down. That isn’t as daft as it sounds as it is the fault of Central Govt that we didn’t build nuclear power plants in this country for decades.
In 2025 the grid intends to operate without gas during periods of high renewables, at which point we'll see even more negative pricing than we do now.Cheib said:
Tom8 said:
Gas will be cheap again next year following deal with US. Broker forecasts look very favourable.
The price of electricity in this country is set off the cost of burning gas to generate electricity….a lot of the electricity is produced at much cheaper rates. There is plenty of room for electricity prices to come down significantly…if the Govt stepped in and said they will subsidise electricity generated by gas then the price of electricity would come down. That isn’t as daft as it sounds as it is the fault of Central Govt that we didn’t build nuclear power plants in this country for decades.I live in a Tudor farmhouse with ~15kW heat loss. Not an ideal candidate for a heat pump.
However, I had a Heat Geek visit a few weeks ago and he said a cascade of 2 heat pumps would be feasible mainly because my existing primary pipework is so big (~35mm external diameter), plus I have a useful area of ground floor wet UFH in a recent extension, plus I have 13kW of wood-burning stoves that would do some heavy lifting in really cold spells.
I would also need to upsize some of the radiators and refit some rooms with insulated plasterboard.
Not a route I want to go down but nice to know it is feasible down the line if government policy leaves me with no choice X years from now.
Ironic that cutting edge technology and government policy would force me to be more reliant on wood-burning stoves, though!
However, I had a Heat Geek visit a few weeks ago and he said a cascade of 2 heat pumps would be feasible mainly because my existing primary pipework is so big (~35mm external diameter), plus I have a useful area of ground floor wet UFH in a recent extension, plus I have 13kW of wood-burning stoves that would do some heavy lifting in really cold spells.
I would also need to upsize some of the radiators and refit some rooms with insulated plasterboard.
Not a route I want to go down but nice to know it is feasible down the line if government policy leaves me with no choice X years from now.
Ironic that cutting edge technology and government policy would force me to be more reliant on wood-burning stoves, though!
So the principal is it will be fine if you throw Enoch energy at it ?
The issue as far as I understand it is they are fine running " normally" but if under stress ( constant heating or low outside temps ) the energy use / cost rises exponentially.
So I don't doubt it is possible but why would you want to consider it?
The issue as far as I understand it is they are fine running " normally" but if under stress ( constant heating or low outside temps ) the energy use / cost rises exponentially.
So I don't doubt it is possible but why would you want to consider it?
Cheib said:
monkfish1 said:
Cheib said:
I’m currently considering an ASHP for a period property…we’ve just had new double glazed windows installed. External doors are either being professionally draft proofed or replaced. A couple of rooms which are colder will be getting internally insulated. We need to do all that regardless of whether we go with ASHP or Gas Boiler or a hybrid system (it’s a big house).
There’s some good advice on here OP. The things I would ask are
- Who specified the heat pump
-Ask to see those calculations
-What other work was done when the heat pump was installed. Rads and possibly larger bore pipes may have been needed. Any insulation ?
-What CoP is the heat pump currently working at. An average of 3 is about right across the year.
The main driver for us looking at one is that we’re getting a fairly large ground mounted solar system with batteries. That potentially means we won’t be buying electricity for half the year and when we do it will be overnight on a tariff of below 10p kWh.
My personal view is as well as throwing subsidies at the problem we’re going to see a change in the pricing differential for electric and gas to make the former more attractive for heating the home. It is only going to get relatively more expensive to heat your home burning gas.
Are you able to give an indication of total costs of all that work? And size of house to give some perspective?There’s some good advice on here OP. The things I would ask are
- Who specified the heat pump
-Ask to see those calculations
-What other work was done when the heat pump was installed. Rads and possibly larger bore pipes may have been needed. Any insulation ?
-What CoP is the heat pump currently working at. An average of 3 is about right across the year.
The main driver for us looking at one is that we’re getting a fairly large ground mounted solar system with batteries. That potentially means we won’t be buying electricity for half the year and when we do it will be overnight on a tariff of below 10p kWh.
My personal view is as well as throwing subsidies at the problem we’re going to see a change in the pricing differential for electric and gas to make the former more attractive for heating the home. It is only going to get relatively more expensive to heat your home burning gas.
Ive done some rough work for mine, Half period stone, half 70's cavity wall. Even doing all the work myself, i think its £35-45K all in. And its only a small place. Not factored in that we will need to move out as well.
Just curious how you make it work? I can buy a lot of oil for £40k
The double glazing and insulation needs doing anyway….roof is relatively cheap, windows very expensive.
We’re having to re-plumb the heating system regardless of whether it is an ASHP or Gas Boiler. We currently have a single pipe central heating system which is incredibly inefficient….so even if we stayed with gas we would really need to do that work. The good news is if we go with ASHP all that replacemnt upgrade work on the heating system is VAT free so that’s a decent saving.
I hear your point about heating oil/£40k but I reckon we’ll be in this house for ten years. I think the pricing differential for houses with shall we call them “legacy” heating systems in ten years time will be tangible…at least in the case of our house because it’s 6000 sq ft. So efficient heating will make a big difference.
The £40k will buy me 20-25 years of oil. Ill be dead or close to it by then, so any payback will be benefit the next owner, not me.
borcy said:
Cheib said:
Tom8 said:
Gas will be cheap again next year following deal with US. Broker forecasts look very favourable.
The price of electricity in this country is set off the cost of burning gas to generate electricity….a lot of the electricity is produced at much cheaper rates. There is plenty of room for electricity prices to come down significantly…if the Govt stepped in and said they will subsidise electricity generated by gas then the price of electricity would come down. That isn’t as daft as it sounds as it is the fault of Central Govt that we didn’t build nuclear power plants in this country for decades.Its what should happen though.
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