Air Source Heat Pumps

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KFT
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Joined: 28 Jan 2015, 8:53pm

Air Source Heat Pumps

Postby KFT » 10 Aug 2020, 9:07pm

Does anyone have any experience of Air Source Heat Pumps (ASHPs).
We are looking into whether this may be a viable option for us. We currently have soalr panels and our main bedroom is south facing so gets and stays very hot in the summer - we were wondering whether we might use ASHPs for cooling as well as heating.
Are there any major disadvantages over conventional heating systems we should be aware of?
Has anyne any recommendations on installers in the Midlands?

Thanks in advance for any opinions

francovendee
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Joined: 5 May 2009, 6:32am

Re: Air Source Heat Pumps

Postby francovendee » 11 Aug 2020, 8:23am

I don't have one but the parents of our friends who live in the Mayenne had it fitted 3 years ago and they are very pleased with it.
Their electricity bill is about half what it was when they heated their home with electricity.

freeflow
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Joined: 29 Aug 2011, 1:54pm

Re: Air Source Heat Pumps

Postby freeflow » 11 Aug 2020, 8:44am

Our neighbour has fitted Air source heating. The plant for the heat exchangers/fans is bout 75 yards from our house. You can hear it working at night which is annoying.

PDQ Mobile
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Re: Air Source Heat Pumps

Postby PDQ Mobile » 11 Aug 2020, 9:47am

I have friends who fitted a system about ten years ago. Replacing an oil fired boiler.

The initial unit failed after several total breakdowns over a few years requiring an engineer from many miles away.

The initial installer went bust and a second installer replaced the whole thing about two years ago. Since then I think just standard maintenance has been carried out.

Expensive overall and needs to be factored in.
Their leccy bill at least doubled because of change from oil.

My view is that, like solar, heat (energy) is produced (available) most economically when when least needed.
When it's brass monkey's outside then the the thing really has to work hard.

So quite noisy, relatively complex, running costs can be higher than the sales(wo)man said.

It may fail just when you need it most, because that is when it works hardest.
Still uses significant leccy.
Ground source is better (and more difficult) IMV.

In the right place may be worth considering though.
However it's not, in my experience, "plug and play" trouble free, for decades.

Cyril Haearn
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Joined: 30 Nov 2013, 11:26am

Re: Air Source Heat Pumps

Postby Cyril Haearn » 11 Aug 2020, 10:18am

Massive (thick walls) building in mud bricks is the solution, very cheap, stores heat and cold, evens out temperature changes
Or dwelling in CSOs, cave-shaped-objects
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Jdsk
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Re: Air Source Heat Pumps

Postby Jdsk » 11 Aug 2020, 11:09am

We looked in great detail into both types of heat pumps when we renovated an old house with solid stone walls 10y ago.

Ground source scored much better than air source. But the economics of either didn't stack up over a 20y reference period. They would have done for ground source in a new build with a new heating system to match.

We were also concerned about the amount of proprietary kit involved and its maintenance and repair on a scale of decades.

We chose a heat recovery ventilation system instead.

But the technology has moved on a bit in 10y and there's a lot more experience in the UK.

Jonathan

Shreds
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Joined: 19 Dec 2010, 4:43am

Re: Air Source Heat Pumps

Postby Shreds » 11 Aug 2020, 7:24pm

Air source heat pumps are definitely noisy and can therefore annoy neighbours at night.

Ground source heat pumps are better but need a very large area for the underground pipework. (Let the field to the local farmer to gaze sheep on!) or install a vertical ground source heat pump, but installation in this case will be expensive and specialist.

We are not quite there yet with all this new technonogy to help save the planet.
Last edited by Shreds on 11 Aug 2020, 8:23pm, edited 2 times in total.

rjb
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Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Air Source Heat Pumps

Postby rjb » 11 Aug 2020, 8:03pm

Some good information on heat pumps here. https://www.renewableenergyhub.co.uk/ma ... eat-pumps/
Our village has had a small estate built recently and they used mains gas to provide heating. This will come to an end as the government will ban the use of gas for heating in approx 5 years time to enable it to meet its fossil fuel obligation. A village 2 miles away has a new estate being built which dosent have mains gas and they are fitting heat pumps. I will have a nose around when the show home opens. I think heating by gas is more flexible and cheaper than using heat pumps for heating. One major advantage of heat pumps is that you can use them for cooling in summer and having solar panels will cut your costs significantly during this period.
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irc
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Location: glasgow

Re: Air Source Heat Pumps

Postby irc » 11 Aug 2020, 8:33pm

rjb wrote:Our village has had a small estate built recently and they used mains gas to provide heating. This will come to an end as the government will ban the use of gas for heating in approx 5 years time to enable it to meet its fossil fuel obligation.


They are talking about banning as boilers in new homes in 2025. Not existing housing.

https://www.theguardian.com/environment ... ls-heating

Gas remains the cheapest way to heat homes. Heat pumps may be viable when the alternative is conventional electric or oil heating. Only a few years ago we had a winter with sub zero temps for days on end. No heat to exchange. Hate to think what electric heating would have cost or if the grid could cope with every home heating full blast after gas was gone.

No subscription needed for the Which report on air source heat pumps.

https://www.which.co.uk/reviews/ground- ... -explained

rjb
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Location: Somerset (originally 60/70's Plymouth)

Re: Air Source Heat Pumps

Postby rjb » 11 Aug 2020, 8:38pm

Thanks irc thats what i meant but badly worded. What happens if you gas boiler breaks down after 2025? will you be able to obtain a new replacement or will you have to fit a heat pump?
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Jdsk
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Re: Air Source Heat Pumps

Postby Jdsk » 11 Aug 2020, 8:41pm

rjb wrote:What happens if you gas boiler breaks down after 2025? will you be able to obtain a new replacement or will you have to fit a heat pump?

The 2025 statement is only for new builds.

Jonathan

irc
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Joined: 3 Dec 2008, 2:22pm
Location: glasgow

Re: Air Source Heat Pumps

Postby irc » 11 Aug 2020, 9:36pm

rjb wrote:Thanks irc thats what i meant but badly worded. What happens if you gas boiler breaks down after 2025? will you be able to obtain a new replacement or will you have to fit a heat pump?


Don't see why not. The new build only idea looks like the start of a gradual switch. The National Grid isn't ready for electric heating. UK peak electricity demand is around 45GW. During the Beast from the East peak gas consumption was 214GW.

https://www.gridwatch.templar.co.uk/

https://ukerc.ac.uk/news/gas-consumptio ... -the-east/

roubaixtuesday
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Re: Air Source Heat Pumps

Postby roubaixtuesday » 11 Aug 2020, 9:51pm

irc wrote: Only a few years ago we had a winter with sub zero temps for days on end. No heat to exchange.


This is a fundamental misunderstanding of thermodynamics.

irc
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Location: glasgow

Re: Air Source Heat Pumps

Postby irc » 11 Aug 2020, 10:32pm

roubaixtuesday wrote:
irc wrote: Only a few years ago we had a winter with sub zero temps for days on end. No heat to exchange.


This is a fundamental misunderstanding of thermodynamics.



An over simplification. But plenty reliable sources say air source heat pumps are less efficient as it gets colder. If back up electric heating needs to be used it will get expensive.

The amount of heat that can be transferred to you home by an air source heat pump is massively reliant on the outdoor temperature. As the temperature outside drops, so does the overall heat output of the air source heat pump.

The heating capacity of the air source heat pump also tends to drop as the outside temperature decreases. The air source heat pump is typically sized to be able to produce heat for 80-90% of your annual load, and when the temperatures are above freezing, it should be able to fill 100% of the heating requirements for your home.

As a result of this, it is recommended that you have a backup source of heating available for when the outside temperature drops. This way, it is able to pick up the slack when your air source heat pump starts to decline in efficiency.


https://www.renewableenergyhub.co.uk/ma ... d-weather/

as the thermometer fell, the bills went up. He was getting about 100 kilowatt hours of heat for each 100 kilowatt hours of electricity he used. This means that in cold weather the unlucky householder is spending eight or nine pounds a day on electricity (multiplied up, £250 a month) but, even more strikingly, he would be better off if he simply installed a few electric heaters in the main rooms. In fact, if I were advising him, I’d say he should turn off the pump whenever outside temperatures fall below about 7 degrees.


https://www.carboncommentary.com/blog/2 ... ld-weather

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[XAP]Bob
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Re: Air Source Heat Pumps

Postby [XAP]Bob » 12 Aug 2020, 12:07am

To say that getting 100kWh of heat per 100kWh of input and your be *better off* installing plain electric heaters is really bonkers.

Refrigerant cycles rely of forced evaporation and condensation by manipulation of pressure, thereby drawing in, or releasing if you look at the other side, the latent heat of vaporisation. That heat must come from the “outside” (heating) or the inside (air con/cooling)

If it doesn’t work at reasonable negative temperatures then can someone please explain the freezer to me? Pretty sure freezers can go down to -20 or so without putting up a fight in the refrigerant unit.
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