Has anyone got any home air source heat pump experience?

[MJJ]

Morning all,

I am considering a swap from our existing, 25 year old, non-condensing oil boiler central heating system, to an air source heat pump. This is in a 70s detached house with radiator only heating, not some wonderfully insulated modern marvel, but we will improve the insulation if we practically can. EPC survey says we are band D, and would benefit from cavity wall and an additional 50mm loft insulation.

I am mainly wanting to do it from a reducing fossil fuel point of view. I don't want to spend fortunes on the change, and through the Green Homes grant scheme, it is a significantly reduced capital investment these days. I am not expecting the monthly bills to reduce greatly, I am expecting to simply replace oil bills with electricity and continue to source renewable electricity. The capital investment case does benefit from the fact that our oil system is old, and will likely need replacement in the not too distant future anyway.

My question/concern is around real world heating and hot water performance with an ASHP. I am told by the various installers that a few larger radiators may be required, but other than that, the ASHP can still provide plenty of heat capacity, even in winter. Everything I read from the ASHP manufacturers say they work most efficiently heating water to c. 40 degrees, but my belief is that our oil system is heating everything to 60 degrees. That seems like quite the reduction in heat output to me.

Anyone got any real world experience to share?

Thanks,

Martin.

 

[Meldrew2]

My wife's family in Canada used to live in a house with air source heating and there was more than sufficient output for a large family home.

I imagine that larger radiators fed by 40degree water will do the same job as smaller radiators fed by 60 degree water, and a larger hot water tank will allow for mixing less cold to shower/bath...

 

[Piff]

Our ASHP heats water to about 50 degrees.
For domestic hot water that is just adequate , but when filling a bath or the washing up bowl, not much cold water needs to be added. Once a week the immersion heater is activated to heat the water to 60 degrees to kill off legionnaires. It's a shock the next morning!
On the heating side, ours feeds underfloor heating and is ideally suited to that. Feeding radiators, you may need to change the radiators to triple panel or larger double panel ones.
Beef up your insulation, don't just add 50mm in the roof, add 150mm instead. Cavity wall insulation is needed and consider lining the external walls internally or externally.

 

[Steveml63]

Hi,
ASHPs are not so good with radiators - they are far more suited to under floor heating (that requires lower water temperatures to work efficiently)
You might get a shock with your electricity bills if you use an ASHP to try and run a radiator based heating system in an older property with poor insulation.
Cheers
Steve

 

[Scooby_Doo]

I've had no experiance of ASHPs but know quite a few people who have/had it. My opinion is that you need to view any claims about heat output from installers / manufacturers the same way you would look at claimed mpg figures from a car manufacturer. You need to get some feedback from someone who's got a similar system in a similar house.

 

[190]

You might get a shock with your electricity bills if you use an ASHP to try and run a radiator based heating system in an older property with poor insulation.

For cheaper running costs there are gas powered heat pumps with 40% lower running costs but the capital cost is higher.

The document below suggests £9000 installed. To be honest the high capital cost of heat pumps would persuade me to do everything possible in the way of improved insulation before spending such a large sum on a heat pump.

https://assets.publishing.service.g...ent_data/file/787321/Gas_Drive_heat_pumps.pdf

 

[Steveml63]

For cheaper running costs there are gas powered heat pumps with 40% lower running costs but the capital cost is higher.

The document below suggests £9000 installed. To be honest the high capital cost of heat pumps would persuade me to do everything possible in the way of improved insulation before spending such a large sum on a heat pump.

https://assets.publishing.service.g...ent_data/file/787321/Gas_Drive_heat_pumps.pdf

Hi,
Quite interesting technology - but only if you have mains gas!
Oil and tank gas are very expensive and the prices vary too much month by month.
Our house in the UK has huge oil boiler and underfloor heating.
When we finally return to UK to live back in that house - we will be looking to replace the oil boiler (100 litres of oil per day consumption in cold winter months!) - with something more economical and green.
We don’t have mains gas - so would be able to install something renewable (ASHP, GSHP, Pellet boiler etc.) - and claim whatever subsidies are available at that time (if any!)
Before moving here in 2012 - I was a renewable energy specialist in the UK and worked with all the technologies available at that time!
Cheers
Steve

 

[BoristheBounce]

I'm currently building a house in the Dales, no mains gas in the village so we are going down the Air Source heat pump route, I wouldn't consider oil or bottle gas the market is just too volatile; I've done a lot of research on it and to be fair, if I could have afforded it, (the house is already costing us £150k over what it started at) I would have gone down the Ground Source heating route as its more efficient.

But the point of my post, is, that, Air Source/ground source is great on a new build with under floor heating (we have it throughout) but it has to be a well insulated property to modern day standards.

The research I've done tells me most people will be disappointed if you are trying to fit Air Source into an existing house with radiators and sub standard insulation, it just doesn't appear to work very well. Obviously this varies house to house depending on age style location etc.

To help pay for the extra electricity I've gone all out on Solar power as our main roof is directly South facing otherwise I know the electric bills will be a shocker. Its not going to help greatly in the winter unless we have sunny winters, but in the summer at least it will help charge my car and run the hot water.

I'm sorry if I've shattered the dream, but I've spent months doing the research and personally I wouldn't even consider fitting it in my current quite well insulted 30 year old house.

 

[Wolfie1]

Hi,
Quite interesting technology - but only if you have mains gas!
Oil and tank gas are very expensive and the prices vary too much month by month.
Our house in the UK has huge oil boiler and underfloor heating.
When we finally return to UK to live back in that house - we will be looking to replace the oil boiler (100 litres of oil per day consumption in cold winter months!) - with something more economical and green.
We don’t have mains gas - so would be able to install something renewable (ASHP, GSHP, Pellet boiler etc.) - and claim whatever subsidies are available at that time (if any!)
Before moving here in 2012 - I was a renewable energy specialist in the UK and worked with all the technologies available at that time!
Cheers
Steve

100l per day holy crap, what have you got a medieval castle!

 

[Londonscottish]

But the point of my post, is, that, Air Source/ground source is great on a new build with under floor heating (we have it throughout) but it has to be a well insulated property to modern day standards.

The research I've done tells me most people will be disappointed if you are trying to fit Air Source into an existing house with radiators and sub standard insulation, it just doesn't appear to work very well. Obviously this varies house to house depending on age style location etc.

I was discussing this with a heating engineer the other day; he was pointing out how quickly ASHP tech has progressed in the 4 years since I specced the gas set-up in my place and how much the costs have dropped as manufacturing has scaled up.

BUT, as others have pointed out, he didn't think I'd get the throughtput I'm used to from an ASHP. Partly because not all of the house is insulated to the very highest standards, partly because an ASHP is still not as powerful as the gas equivalent.

 

[190]

It seems to me that rather than worry about radiator sizes and spending money on bigger ones, any money would be better spent on improving insulation. If you take a 30 year old house like mine then presumably the radiators were sized for the standard of insulation at the time. I've improved the insulation considerably since then and that can be readily seen in substantially reduced gas consumption. I don't think I would have a problem with an ASHP if it ran at 50 deg C.

 

[MrGreedy]

One of the biggest issues for thermal efficiency of older housing is not the insulation, but draft proofing. Poorly fitting vents, extractors, doors, Windows, loft hatches, letter boxes, key holes, skirting to under floor drafts etc etc.
Chucking loads of insulation has little effect if the drafts aren't sorted, and they are technically difficult to get right and are often not sorted due to poor fitting at install of e.g. new 'energy efficient' front door.


My dad signed up for the green grant thing last year to get an ASHP. He was one of the first and it took 16 months to get the go-ahead (even though it was supposed to be done and dusted in 12 months. They only have electric at the property.

Having applied for the grant he made enquiries within a 150 mile radius of the Southampton and couldn't find any installers who were interested in Government supported schemes, as they'd all been burnt in the past doing jobs and then chasing the money for another year from Gov.

Another factor was that ASHPs were a lot more expensive than aircon. To the point that taking into account the grant, aircon was the same price to the homeowner as ASHP (ignoring the fact you couldn't actually get anyone to fit ASHP with a grant top up).

Pros and cons.
Aircon can heat and cool the room very quickly because it heats the air in the room and blows it around, and you just turn on what you need in the room. Cheaper install. You are not heating a load of radiator water. But, you don't get hot water from it so they continue with eleccy shower and immersion heater for the tanks (solar to top this up in the day is the next option they are looking at, storing anything not used as heat energy rather than going down the battery route).
Might get some room floor space back where you elect for high mount aircon units.

ASHP do give you heat and hot water, but don't cool you down in the summer. More expensive install. Might lose some floor or wall space depending on radiator size upgrades. Might be some Gov grants available of questionable commercial merit.

 

[BoristheBounce]

One of the biggest issues for thermal efficiency of older housing is not the insulation, but draft proofing. Poorly fitting vents, extractors, doors, Windows, loft hatches, letter boxes, key holes, skirting to under floor drafts etc etc.
Chucking loads of insulation has little effect if the drafts aren't sorted, and they are technically difficult to get right and are often not sorted due to poor fitting at install of e.g. new 'energy efficient' front door.


My dad signed up for the green grant thing last year to get an ASHP. He was one of the first and it took 16 months to get the go-ahead (even though it was supposed to be done and dusted in 12 months. They only have electric at the property.

Having applied for the grant he made enquiries within a 150 mile radius of the Southampton and couldn't find any installers who were interested in Government supported schemes, as they'd all been burnt in the past doing jobs and then chasing the money for another year from Gov.

Another factor was that ASHPs were a lot more expensive than aircon. To the point that taking into account the grant, aircon was the same price to the homeowner as ASHP (ignoring the fact you couldn't actually get anyone to fit ASHP with a grant top up).

Pros and cons.
Aircon can heat and cool the room very quickly because it heats the air in the room and blows it around, and you just turn on what you need in the room. Cheaper install. You are not heating a load of radiator water. But, you don't get hot water from it so they continue with eleccy shower and immersion heater for the tanks (solar to top this up in the day is the next option they are looking at, storing anything not used as heat energy rather than going down the battery route).
Might get some room floor space back where you elect for high mount aircon units.

ASHP do give you heat and hot water, but don't cool you down in the summer. More expensive install. Might lose some floor or wall space depending on radiator size upgrades. Might be some Gov grants available of questionable commercial merit.

I can't agree more regarding the draught proofing this is one of the advantages with putting in a ASHP in a new build, you have control over this type of thing.

The trouble with blown heat which is what I think you are referring to as Aircon is very very dry heat it causes problems for lots of people and just isn't nice to live with.

A town close to where I currently live built all their new houses in the 60's (council houses then) with this type of heating, without fail it was all gradually ripped out in favour of other types. I remember visiting someone who had it, it dries the air and makes the atmosphere very stale.

Before you ever install this make sure you visit a property in the winter when its being used and see what its like.

 

[190]

It's occurred to me that there will a problem or at least substantail additional cost involved in providing hot water when we move to heat pumps.

Most houses that have modern condensing boilers installed have used a combi boiler providing mains pressure instantaneous hot water rather than an indirect hot water tank. Presumably the hot water tanks and cold header tanks that fed them have been discarded. This provision of high pressure hot water is only possible because combi boilers have a very much higher output when heating hot water than they need for heating the radiators. I can't see heat pumps being capable of anywhere near the typical 30KW needed to provide instantaneous heating of hot water.

So how is it going to work. Some storage of hot water seems essential, does that mean the need to reinstall conventional hot water tanks and bearing in mind that new builds will have sized pipework and taps to function on a high pressure hot water supply does that also mean high pressure mains fed hot water tanks are required which don't come cheap.

 

[Bellow]

Will heat pumps prevail? I believe the government are soon going to announce funding for this >> The Acorn Project
A quick summary of the project reads like this. Take North Sea gas and use some of it to create hydrogen the CO2 from which will be captured and stored in redundant oil wells under the sea. The hydrogen will be infused into natural gas supplied domestically at 2% initially, rising to 20% with a final aim of 100% hydrogen. At that level, presumably the boilers and hobs need some adapting but utilising the existing natural gas pipelines is without any need of modification.
Strikes me changing the jets on boilers and cookers is a shedload easier than what installing heat pumps entails. And proper hot water to boot.

 

[ChrisHGTV]

I can't agree more regarding the draught proofing this is one of the advantages with putting in a ASHP in a new build, you have control over this type of thing.

The trouble with blown heat which is what I think you are referring to as Aircon is very very dry heat it causes problems for lots of people and just isn't nice to live with.

A town close to where I currently live built all their new houses in the 60's (council houses then) with this type of heating, without fail it was all gradually ripped out in favour of other types. I remember visiting someone who had it, it dries the air and makes the atmosphere very stale.

Before you ever install this make sure you visit a property in the winter when its being used and see what its like.

We had air heating in our old house. One advantage is you don't have radiators and you can run it on cool in the summer which helps. One thing we found though was that it heated the house quickly but then as soon as you turned it off it would cool very quickly too (compared to radiators which i guess continue to emit some residual heat). It was also noisy - not disturbingly so but it wasn't silent because of the fan. And yes we ended up having various humidifiers around the house. I wouldn't go back - rads and wet underfloor is what we have now.

 

[BoristheBounce]

So how is it going to work. Some storage of hot water seems essential, does that mean the need to reinstall conventional hot water tanks and bearing in mind that new builds will have sized pipework and taps to function on a high pressure hot water supply does that also mean high pressure mains fed hot water tanks are required which don't come cheap.

I think the answer to that is yes, to be totally honest I'm no guru on this but from what I remember the engineers saying is that the pressure of the mains water forces the hot water out at mains pressure, how I don't know; this was in a response to me saying that I wanted a good high pressure pump for the showers etc, and he said it wouldn't be needed due to how the system worked.
Time will tell

 

[ChrisHGTV]

I think the answer to that is yes, to be totally honest I'm no guru on this but from what I remember the engineers saying is that the pressure of the mains water forces the hot water out at mains pressure, how I don't know; this was in a response to me saying that I wanted a good high pressure pump for the showers etc, and he said it wouldn't be needed due to how the system worked.
Time will tell

I think ours works like this - we have a Megaflo.