Air Source Heat Pump Renewable Heating?

Dominic-Toretto

Dominic-Toretto

Dominic-Toretto

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Hey everyone,

Has anyone on OCUK installed one of these systems in their home. I am currently considering replacing an old gas based system and am concerned that an air source heat pump will not actually provide enough heat. I have read lots of mixed opinions online, whats the general train of thought on these? Are they any good?

Thanks
 
I had a Vaillant ASHP installed 18 months ago to replace a Coal fire/back boiler.
Coming from a coal fire, we obviously miss the direct intense heat, but the radiators are controlled by a room thermostat as well as individual TRVs, and the house never feels cold .

Over winter there was a definite saving in cost versus coal, and throughout the rest of the year it's added very slightly to our electric costs (~£3/week), but with the advantage of heating first thing on a cold morning (whereas we wouldn't necessarily have bothered lighting the fire), and hot water twice a day without having to rely on the immersion heater.

Noise was initially a concern when the unit was first installed, however I changed the unit to operate exclusively in Low Noise mode, which made things much better, and is barely a low hum despite the unit being installed just outside a window.
 
Armageus said:
I had a Vaillant ASHP installed 18 months ago to replace a Coal fire/back boiler.
Coming from a coal fire, we obviously miss the direct intense heat, but the radiators are controlled by a room thermostat as well as individual TRVs, and the house never feels cold .

Over winter there was a definite saving in cost versus coal, and throughout the rest of the year it's added very slightly to our electric costs (~£3/week), but with the advantage of heating first thing on a cold morning (whereas we wouldn't necessarily have bothered lighting the fire), and hot water twice a day without having to rely on the immersion heater.

Noise was initially a concern when the unit was first installed, however I changed the unit to operate exclusively in Low Noise mode, which made things much better, and is barely a low hum despite the unit being installed just outside a window.
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Did you have to upsize your rads to make heat pump work for you? :)
 
Biggest mistake I made was taking the solid fuel/back boiler out and putting a combi in. Yes I've probably saved loads (plus instant hot water) versus buying solid fuel but you just can't beat the heat and the cosiness of the fire.
 
Armageus said:
Yep all our radiators were replaced and new larger diameter piping run everywhere.
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Thanks, good to know.

How much did the entire system cost including pipework and rads?

Do you get any money back via RHI on top of the heat it supplies your home?

I assume it supplies your hot water as well, does that need a special cyclinder?

How is the noise - do you think it would be an issue with neighbours close by? (thinking windows open on summers nights)?

Thanks again!
 
Mr.Stu said:
How much did the entire system cost including pipework and rads?
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Couldn't tell you unfortunately, as was installed whilst we were council tenants (although we've just bought the house via right to buy in the last fortnight)

Mr.Stu said:
Do you get any money back via RHI on top of the heat it supplies your home?
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I should be able to claim the remaining 5 years or so of the RHI, but just waiting for the paperwork to do with the house purchase and a copy of the AHSP installation certificate to be made available.

Mr.Stu said:
I assume it supplies your hot water as well, does that need a special cyclinder?
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It does, although there is also a standard electric element as well, if you want hot water outside of any pre-programmed ASHP DHW periods.
I believe it is a pre-plumbed Unistor cylinder (looks like the leftmost one of the 3 in the first picture on the site below)
https://www.vaillant.co.uk/for-installers/products/unistor-heat-pump-cylinders-42752.html


Mr.Stu said:
How is the noise - do you think it would be an issue with neighbours close by? (thinking windows open on summers nights)?
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As mentioned briefly above, when first installed it was loud enough that I wasn't happy with it, and I doubt the neighbours were either. However I checked through the settings, and enabled low-noise mode at all times. Since then it's a low-hum that's difficult to notice from inside, and even standing next to the unit (or having a window open) it's not excessive.
It's difficult to describe or gauge a loudness, but probably a similar level to the fans in my electric oven, certainly a washing machine or tumble dryer is probably noisier than the ASHP.
(In standard mode the noise was probably more equivalent to a Lawn mower!)

The ASHP unit we have is a AroTHERM:
https://www.vaillant.co.uk/for-installers/products/arotherm-air-source-heat-pump-2944.html
 
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Been looking into this as we've been looking into a lot of properties not connected to the gas network, and Scottish Government want to phase out fossil fuel heating.

Still a lot of talk that the houses need to be super insulated/airtight so not maybe not always practical for older houses (what we're wanting to purchase). As said they typically run slower and colder than traditional CH systems so need to look at radiator systems, people either go larger or aluminium radiators are recommended.
There are hybrid systems, using either gas or oil as a top-up system for when it's really cold but almost defies the point if you're wanting to install to move away from fossil fuels. Some posters say their system only uses the hybrid side for coldest January days or "beast from the east" scenarios.
Newish on the market are high temperature ASHP, designed to replace current boilers without changing radiators or for the larger older houses. From memory they take the temperature output up from 60c to 80c. I've not found much information from forum posters online about these to gauge if they actually say what the claim to.

Every-one seems to have an other means to also heat up the hot water tank, back boiler from a wood burner, using solar etc.
 
Bit of a thread bump, but I assume these are becoming more and more popular with the advancement in ASHP technology and the rising cost of energy prices - any more members with experience of heat pumps now?

We're performing a full renovation on our bungalow which includes new windows and doors throughout, full floor insulation, external wall insulation, and 300mm of loft insulation. We'll also be running hydronic underfloor heating so I fully believe we'd be stupid to consider anything other than an ASHP for heating needs - with the long term idea of feeding the ASHP with solar panels making it a fully green system.

We've looked in to our options and put a Valliant Arotherm Plus at the top of our list, reasons being that it's Quietmark accredited and can offer flow temps of 75c, so shouldn't have to rely too much on the immersion heater for water temperature top ups.
 
I think this might be a popular topic for sure, I’d really like to learn more. Our new build sadly has micro bore so 8? Or 10? Mm OD pipes to the radiators, I hear that you need larger pipes for more flow through larger radiators to account for the lower delta difference of the water temp?

I hear that microbore can work, but you need faster flow for smaller diameter piping to the rads, so potentially putting more strain on the pumps etc?

We often gets times during winter where we are, bottom of a valley north west England where the temps are around 0-4c with high humidity and wonder if during these times all that will happen is constant thawing cycle of the ASHP Unit.
 
Dominic-Toretto said:
Hey everyone,

Has anyone on OCUK installed one of these systems in their home. I am currently considering replacing an old gas based system and am concerned that an air source heat pump will not actually provide enough heat. I have read lots of mixed opinions online, whats the general train of thought on these? Are they any good?

Thanks
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I guess my question would be 'Why are you not just looking to replace it with a more modern gas boiler?'
 
I’m keen to hear other people’s experience too. I’m currently gathering quotes for ASHPs and trying to do everything I can to insulate my home more. I’ve had solar panels for a year and anything I can do to make the house more eco-friendly is a positive.

Can anyone share the prices they’ve paid for an ASHP installation and what it covered? e.g. ASHP brand & power, number of radiators replaced, hot water cylinder type & size etc.

The indicative quotes I’ve had so far are around £15k for the 14kW ASHP, 300 litre cylinder and a few radiator replacements. I had a heat survey carried out last week and I’m waiting on the first formal quote which will hopefully provide more detail on what’s needed.
 
We had an indicative quote to replace our 35kw Saunier Duval boiler with an air source heat pump, which included an electric calorifier, changes to plumbing, increase in radiator size, heat pump install, additional consumer unit (ours is full) and wiring and it was an eye-watering £22k, we didn't bother pursuing a detailed quote. Hence now looking at a hydrogen ready replacement condensing boiler. I think the money for me would be better spent on solar and a battery and still have £12k in my pocket.
 
Coran said:
Snip.
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Is 14kw recommended due to being on traditional, but enlarged, radiators?

Our property is not classed as small with approximately 125 sq/m of underfloor heating area, and apparently only need a 7kw heat pump. I'm wondering whether this is because of the large area of heating at low temperatures or whether it's insulation level based, or is your house huge?
 
PermaChanged said:
Bit of a thread bump, but I assume these are becoming more and more popular with the advancement in ASHP technology and the rising cost of energy prices - any more members with experience of heat pumps now?

We're performing a full renovation on our bungalow which includes new windows and doors throughout, full floor insulation, external wall insulation, and 300mm of loft insulation. We'll also be running hydronic underfloor heating so I fully believe we'd be stupid to consider anything other than an ASHP for heating needs - with the long term idea of feeding the ASHP with solar panels making it a fully green system.

We've looked in to our options and put a Valliant Arotherm Plus at the top of our list, reasons being that it's Quietmark accredited and can offer flow temps of 75c, so shouldn't have to rely too much on the immersion heater for water temperature top ups.
Click to expand...

UFH is a good case for ASHP.

What are you planning to do with water at 75C? The limiting factor for many heat pumps is domestic hot water, which typically needs to be kept about 55/60C to prevent legionella. In a domestic setup, if you have stored water you can limit that flow temperature somewhat. For underfloor, you probably wouldn't need 75C. Maybe 60C max?

5K reduction in heat pump flow temperature gives in efficiency improvement of 10-15% and will improve your SCOP substantially, so the lower you can run it the better.

Don't think in terms of flow temperatures you have used before - UFH and domestic hot water don't need it.
 
I suppose in hindsight I don't need the 75c flow temps, as long as the ASHP is indirectly heating water for the hot water cylinder to 60/65 all's well - or even lower if I want hit higher SCOP and top up water temps with the immersion.

Flow temperatures for the UFH are lower, but this water temp is controlled by the manifold by mixing hot and cold together.
 
PermaChanged said:
Is 14kw recommended due to being on traditional, but enlarged, radiators?

Our property is not classed as small with approximately 125 sq/m of underfloor heating area, and apparently only need a 7kw heat pump.
Click to expand...

I'm heating a small 3 bedroom house (89m2 floor area) with a 5.5Kw Vaillant Arotherm and enlarged rads, although our house is reasonably energy efficient - EPC rating of D (66)
 
PermaChanged said:
Any complaints with the setup through the depths of winter? Is it proving to be cost effective?
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Has worked fine even through cold weather, when installed was considerably cheaper in terms of running cost vs the coal fire it replaced, although currently I have a fault with it that I'm dealing direct with Vaillant with (fan seems to be stuck in noise reduction mode affecting efficiency) so taking a bit longer to warm up and using a bit more energy.
 
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