[Zippeh]

Any experts on here regarding air source pumps?!

I'm investigating swapping out our gas boiler for a pump. This would involve fitting an unvented cylinder in the garage (no room in house) which would be heated by the pump and solar panels using an Eddi diverter to heat hot water when the electricity is not being drawn by the house from the panels.

Just wondering what of people's experiences with any savings, and if the radiators have been hot enough etc?

Thanks!

[xenon]

In laws moved to a new-build where a ground-source heat pump was fitted as part of its green credentials. Utterly terrible POS that cost a fortune in electricity (despite solar panels) and nobody could seem to get it to work efficiently. Eventually ripped out and replaced with a gas combi. There's environmentally friendly for you....

[Eddamoo]

Watching the thread with interest. I'm by no means an expert, just been idly looking into them for the next house. With the amount of green electricity infrastructure we're building, they are certainly the future when looking to move to net-zero carbon.

Some key considerations are their efficiency in a realistic use-case. Even though we don't have super-cold winters, they are certainly humid. This can regularly clog the heat-exchangers with Ice affecting their Coefficient of Performance quite drastically, 5:1 at 7C would move closer to 2:1 at -5C (where you really want it!).

From what i read of some year-round studies, modern systems are on-par with gas boilers for domestic heating and hot water at around 55C. If you want water hotter, i've read that it needs auxiliary heating at more expense.

You would likely need double/double rads and a very powerful pump to compensate for the lower input temperatures, but as said im no expert!

[robwils]

Originally Posted by Eddamoo

Watching the thread with interest. I'm by no means an expert, just been idly looking into them for the next house. With the amount of green electricity infrastructure we're building, they are certainly the future when looking to move to net-zero carbon.

Some key considerations are their efficiency in a realistic use-case. Even though we don't have super-cold winters, they are certainly humid. This can regularly clog the heat-exchangers with Ice affecting their Coefficient of Performance quite drastically, 5:1 at 7C would move closer to 2:1 at -5C (where you really want it!).

From what i read of some year-round studies, modern systems are on-par with gas boilers for domestic heating and hot water at around 55C. If you want water hotter, i've read that it needs auxiliary heating at more expense.

You would likely need double/double rads and a very powerful pump to compensate for the lower input temperatures, but as said im no expert!

Yes we have them at work, certainly can take a while to warm up the room on the coldest of winter days. I’m looking at getting one for our garden room but mainly as they do dual aspect of cooling and heating....

[k755]

Have a Mitsibushi air force heat pump in my conservatory,works very well will pump out hot air when -5 outside within 2 mins and can also reverse to use as air con. Not sure about a whole house would need a large unit and seperate outlets in most rooms.

[gangzoom]

Originally Posted by Zippeh

Just wondering what of people's experiences with any savings, and if the radiators have been hot enough etc?

How old/big is the house, and how much solar PV have you got already?

I've looked seriously at one inregards to the house renovations we are doing this year. I already have solar PV+home battery so was keen to look at all options.

However essentially it seem heatpumps only really work in well insulated houses build from the ground up to retain heat. Retrofitting to an existing build is pretty much pointless.

Running costs are also quite high depending on how much self generated electricity you can spare, cold/dark days = no sun, so you will be powering the thing straight off the grid and electricity prices aren't getting cheaper.

Better insultation and/or increasing the solar PV array will be more cost effective.

[The Flying Moose]

So we have a grant aerona 3 air source heat pump and it’s been in for around 3 years so I can probably give a reasonable review.

In our case we live outside of mains gas and the house was originally fitted with a warm air heating system which was woefully expensive and inefficient.

The house is very well insulated with new cavity and loft insulation and all windows and doors were updated and replaced last year.

We’ve had a number of issues and had quite a lot replaced under warranty included a new main board which would have been nearly a thousand pounds.

The system itself heats the water and radiators and warms our 4 bedroom house to around 23 degrees with relative ease, albeit slowly. As stated above in the winter months there is a lot of demand on the system and costs can be quite high. We’ve had a number of heating specialists in to “set it up” and it’s serviced annually. We’ve come to the conclusion and by recommendation that’s it’s most efficient and cost effective when left on permanently as maintaining a heat is cheaper than cooling and re heating.

Initially I was disappointed with the system as the house was always cold but after a lot of tweaking it now seems to work well, certainly doesn’t have the ease of a combi boiler setup.

Sadly this all comes at a cost... for instance today our smart meter is already reading 26.96 kWh use since midnight, barring the usual white goods nothing else has been on and that’s £3.25. In the colder months it’s over £200 a month to keep the house warm and powered (circa 20/21 degrees) it is however significantly cheaper in the milder months as little as £50.

Some of the cost can be offset by RHI grants up to 1200 a year but these are time limited.

If I had my time again I probably would have looked at oil for us given the option of no gas.

[Zippeh]

Originally Posted by gangzoom

How old/big is the house, and how much solar PV have you got already?

I've looked seriously at one inregards to the house renovations we are doing this year. I already have solar PV+home battery so was keen to look at all options.

However essentially it seem heatpumps only really work in well insulated houses build from the ground up to retain heat. Retrofitting to an existing build is pretty much pointless.

Running costs are also quite high depending on how much self generated electricity you can spare, cold/dark days = no sun, so you will be powering the thing straight off the grid and electricity prices aren't getting cheaper.

Better insultation and/or increasing the solar PV array will be more cost effective.

We would have 9 panels installed at 320W each. They would be facing South-South Westerly. House is about 14yrs old, and we'd need to fix draught issues with existing UPVC door and windows (will do this anyway!)

Looking at getting cavity wall insulation done as it's not present in this house. We had it in old house, but only been here for 1.5mths.

[JNW1]

Originally Posted by gangzoom

How old/big is the house, and how much solar PV have you got already?

I've looked seriously at one inregards to the house renovations we are doing this year. I already have solar PV+home battery so was keen to look at all options.

However essentially it seem heatpumps only really work in well insulated houses build from the ground up to retain heat. Retrofitting to an existing build is pretty much pointless.

Running costs are also quite high depending on how much self generated electricity you can spare, cold/dark days = no sun, so you will be powering the thing straight off the grid and electricity prices aren't getting cheaper.

Better insultation and/or increasing the solar PV array will be more cost effective.

We're on LPG where we live - which is more expensive than mains gas - so when our combi boiler started to give problems late last year I made enquires about switching to a heat pump. The firm I talked to fitted heat pumps as well as conventional boilers - so in theory had no axe to grind - but the chap was quite straight in saying the heat pump wouldn't be more efficient in our house; as you say, it needs a good standard of insulation and, because the water in the system doesn't get as hot, you potentially need to fit larger radiators as well in order to get an equivalent level of heat in the house.

So, even after the grants available, the total cost of conversion was still going to be quite a bit more expensive to install and, from what I was told, the life expectancy of the heat pump itself isn't much better than a combi boiler either (typically circa 15 years in each case). The net result was we just had a new Worcester-Bosch LPG combi boiler installed - quite where that will leave us when that one gives up the ghost and equivalent replacements are no longer allowed is another matter.....

[Lynxi2k]

Originally Posted by JNW1

We're on LPG where we live - which is more expensive than mains gas - so when our combi boiler started to give problems late last year I made enquires about switching to a heat pump. The firm I talked to fitted heat pumps as well as conventional boilers - so in theory had no axe to grind - but the chap was quite straight in saying the heat pump wouldn't be more efficient in our house; as you say, it needs a good standard of insulation and, because the water in the system doesn't get as hot, you potentially need to fit larger radiators as well in order to get an equivalent level of heat in the house.

So, even after the grants available, the total cost of conversion was still going to be quite a bit more expensive to install and, from what I was told, the life expectancy of the heat pump itself isn't much better than a combi boiler either (typically circa 15 years in each case). The net result was we just had a new Worcester-Bosch LPG combi boiler installed - quite where that will leave us when that one gives up the ghost and equivalent replacements are no longer allowed is another matter.....

I also looked into this as an alternative to Oil before we moved house back onto the grid. Seems to be most effective when combined with underfloor heating, in some cases only sold as a solution with a view that underfloor heating would also be installed. This raised the install costs to £10-15k(for a 3 bed semi) and as has been pointed out above, it wouldn't be "hot" in the traditional sense.

When all taken into consideration, including running costs, couldn't justify it any cost or environmental sense.

Have you looked at IR radiators instead? Instant heat and could be a better alternative to Heat pumps, if you need electric heating.

[KRS_SN]

Great cost and hardship to go carbon neutral seems to be in fashion. Like used v8's/m cars in the future probably there will be a strong second hand market for used combi boilers with full service history of course.

[Wills2]

I think that's the rub, the carbon neutral tomorrow doesn't include the convenience/utility of our current carbon intensive today.

[AlanQS]

When we installed air pump systems, we had to specify D3 radiators which are triple rather than double and with a greater area. Some of them are huge, weighing over 100kg. Because the water doesn't get as warm, you need a much larger area of radiator surface.

Also, location can be a problem as they can make some noise and you have to be within a certain volume level before you can install it. You probably also need an anti-vandal cage to protect the gubbins of it, dependent upon where you live.

[JNW1]

Originally Posted by Lynxi2k

Have you looked at IR radiators instead? Instant heat and could be a better alternative to Heat pumps, if you need electric heating.

I haven't looked at IR radiators but, if LPG combi boilers are outlawed by the time the one we've just fitted needs to be replaced, it may be one of the options we need to consider. However, it will all depend on what alternatives are available 15 years from now so I'll cross that bridge if and when I come to it!

[Malone]

Gas: 3p kWh - lose some efficiency, so say 4p.
Electric: 16p kwh.

I just can’t see the running costs of a heat pump being competitive - you’ll need a heat pump that’ll run with a 4:1 coefficient in the middle of winter, just to be the same price as gas. I doubt there’s a heat pump that’ll manage that (although I may be wrong)!
Plus they’ll take longer to heat the house as they don’t give out hot enough water and then I think you have to have something installed that can periodically heat the water in your cylinder to over 65c to prevent legionella.
At the point gas costs the same as electric, then it might be worth it, but then you’ve got the massive install costs too

[EvilDrPorkChop]

If you've got mains gas then a ASHP isn't worth it. They won't do away with condensing boilers either, they're all going to be converted to run on Hydrogen (very little actually needs doing for this to work). ASHP aren't a viable option for 95% of homes.

If you're on oil, or off grid then it might be a different matter.

[Toby1990]

We’re in a 2 year old new build (small local builder} with ASHP for heating and hot water - no mains gas available.

Takes some getting used to - not the instant heat that a combi will give - but overall happy.

Current monthly leccy bill DD is £110/month. That’s for a 4 bed detached.

I think as others have said, will work for new build but poss not so great to try and retro fit.

[Lynxi2k]

Originally Posted by JNW1

I haven't looked at IR radiators but, if LPG combi boilers are outlawed by the time the one we've just fitted needs to be replaced, it may be one of the options we need to consider. However, it will all depend on what alternatives are available 15 years from now so I'll cross that bridge if and when I come to it!

I have now inherited an old gas boiler similar age to my old oil boiler but will wait and see what government incentives might arise for conversion to a more efficient system.

Just about got an application for cavity will insulation in before the government scrapped ghg. I suspect if burning oil is outlawed in the future you will be looking at partially funded alternatives, but tech should have moved on loads by then and solutions improved. 🤞

[TiredGeek]

You can make ASHP work in an old, poorly insulated house, but it does cost serious money and considerable effort to do so. I've got 2 x 14kw Mitsubishi air to water units at my Scottish place. 18 inch solid stone walls.

The system is complex, requires a silly amount of radiators and is anything but cheap to run. However, the last bit is possibly down to our usage pattern which isn't really what they're designed for. It's a holiday home so mostly kept on frost 'stat at 10'c....
Total cost including rads, pumps, pipework and the special antifreeze you have to run in the system came in just around £20k. Bearing in mind I did all the install and just had the manufacturer in for commissioning you could probably add another £10k for a company installed system.
When we priced up an oil system we were looking at around £7k.
This last year I have not set foot in the place, November 2019 to today, 10'c set, £1747.80 in electric.

We did go into this with open eyes though. We had no options other than oil / LPG / heat pump. As oil theft around our place is common (crofters) and LPG was difficult to source (no one was interested - "too remote"), we had to go heat pump.

In short: if you have access to mains gas don't even consider ASHP. If you have an old poorly insulated house, think VERY carefully, oil is considerably cheaper all round - unless it gets stolen.

[HighlandPete]

I'm also following this thread with interest...any more experience?

An ASHP system is not making any sense to me for my home, although running on electric, with the high unit cost, but virtually no maintenance costs. Any way forward is very expensive.

One of my neighbours has gone for a ASHP system, required the house to be vacant for a week while it was pulled apart and upgraded for installation.

On a technical level, the ASHP was put on the North side of the house... to make installation easy, but is goes against all sense to me. The South side gets the sun in winter and the air temperature climbs, say 10-degrees, while the North side stays frozen. Surely to make the system most efficient, getting as much heat as possible is key to running costs.

I've a feeling there is a "get on the 'bandwagon" approach by some companies, without the full technical knowledge/experience of how to gain maximum efficiency.

My son renovated his current home, he put the money into insulation, not a complex heating system. I see this would be absolutely necessary in my home, to make any sense of an ASHP, or wouldn't be saving much (me or the planet), even long term.

[Witney]

Insulation, insulation, insulation and air tightness....save the passive energy leakage first before addressing the efficiency of the source of energy production. Unless of course the existing unit fails and there is an opportunity.

[xenon]

Originally Posted by HighlandPete

I've a feeling there is a "get on the 'bandwagon" approach by some companies, without the full technical knowledge/experience of how to gain maximum efficiency.

Absolutely - the in-laws saved a fortune by going to a traditional gas combi so even environmental considerations are dubious, never mind efficiency ones. There's was a Mitsubishi unit and it ran constantly but all the "experts" opined that there was nothing wrong with it. Load of old toss IMO.