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200 year old farmhouse in Cornwall

Air Source Heat Pumps (ASHPs)

Last Post by Kev M 4 years ago

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Rodgero

(@rodgero)

New Member Member

Joined: 4 years ago

Posts: 2

Topic starter 20/10/2021 7:29 pm

Hi - we recently moved to a 200 year old farmhouse in Cornwall. We don’t have heating apart from a wood burner and some storage heaters that don’t work. Neighbors have LPG tank but we’re trying to go green. I’ve had two ASHP quotes. I’ve also had plumbers builders and an architect tell me ASHP would be a waste of money in an old house because our EPC is rated E. We have solid walls and concrete floors so I don’t know if we would be better off tackling the insulation first. I just wondered if you had found the ASHP to be worthwhile. It’s going to cost £18-20,000 for the pump and installation of the new heating system so I don’t know if I’m better off just getting electric oil heaters and looking at solar instead. Solar panels and an 8khz battery is in the region of £10k and I could get electric under floor heating mats. But no RHI on solar. Any advice appreciated. Thanks

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Mars

(@editor)

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Joined: 5 years ago

Posts: 3838

20/10/2021 8:10 pm

@rodgero, welcome to the forums. Insulation has to be the starting point. An E EPC rating is on the lower end and you may struggle to heat the house efficiently using a heat pump, but it will still be more efficient than electric heaters.

We have the solar and unfortunately it doesn't produce the amount of power you need from Nov-Feb.

£18,000-£20,000 for a heat pump is expensive. May I ask what size you've been quoted for, what is the square footage of the property and does this include upsizing of rads?

Since I don't know what your property looks like, would an air-to-air heat pump work better as opposed to air-to-water.

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Rodgero

(@rodgero)

New Member Member

Joined: 4 years ago

Posts: 2

Topic starter 20/10/2021 9:53 pm

I've attached the farmhouse floorplan. We've only been in the property since July so we don;t know all its quirks. The ground floor is not level and seems to be concrete or solid rock. The walls are solid stone/cob with no cavity and some damp, possible just condensation but also unlikely to have DPC as the house is very old. The roof is slate. There is about 150mm rockwool insulation in the loft. The windows are a hodge podge of single and double glazed, all wooden frames. The front and back doors are drafty as heck. I don;t really know about air to air - I'll google it shortly

Global Energy Systems quoted £18,987 ex VAT for a 18kW Caernafon (£8,200) and full wet rad installation (£7,995)

GreenGenUk quoted £17,271 ex VAT for the following:

- Mitsubishi Ecodan 11.2kW Heat Pump with FTC6 Controller

- 300-litre Single Coil Unvented DHW Cylinder

- 6 Double Convector Radiators and 1 Towel Rail for Ground Floor

- 5 Double Convector Radiators and 1 Towel Rail for First Floor

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MikeFitz

(@mikefitz)

Trusted Member Member

Joined: 5 years ago

Posts: 29

20/10/2021 10:07 pm

Looks like you have a lot to do in draft proofing alone!

If I was staring afresh I would not ignore UFH. Most plumbers think you need 12" of insulation under the pipes but there are modern clever ways where the pipes are embedded in insulation.

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Radiators are easier to fit and install companies like to do things quickly.

I wish you well!

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Derek M

(@derek-m)

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Joined: 5 years ago

Posts: 4425

21/10/2021 4:13 pm

Hi Rodgero,

You may have left it a little late to get everything sorted this year.

As others have stated, insulation would be your best starting point, since it will provide you with lower heat loss, therefore lower heat demand and better efficiency.

Since you have solid walls you may wish to consider internal or external wall insulation. I am not an expert, but I would think that external wall insulation and waterproofing, though more expensive than internal, could be more beneficial. External insulation would also mean that the thick walls would be able to act as a thermal store and help regulate the internal temperatures and improve efficiency.

A starting point would be replacing your doors and windows where necessary.

Once you have improved the level of insulation, you should find that the size of heat pump required and associated costs are quite a bit lower than those quoted. If you sufficient land available you might wish to consider a ground source heat pump, which are more efficient than an air source, though more expensive to install. Another important factor for highest efficiency, is to have heat emitters (radiators or UFH) that provide the greatest output value, which in turn will allow a heat pump to operate at the lowest water flow temperature.

You may also wish to consider solar PV to help power an ASHP and also help to provide hot water.

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Kev M

(@kev-m)

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Joined: 5 years ago

Posts: 1276

22/10/2021 3:38 pm

Hi @Rodgero, we were quoted c.£16k inc vat for a 14kW Ecodan, a 250l HW cylinder and the same number of rads as you. We had no central heating. Our house is 160 m2 and quite well insulated. It all works well.

The two quotes are very different in terms of the size of ASHP. Our installer thought the 11.2 Ecodan was borderline so we went for the bigger one. I'd worry it's too small for your place.

What is your annual space heating and HW use on your EPC? You will need 270mm of loft insulation if you want RHI and I'd definitely look at this and draft proofing in the short term.

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