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Thinking of ASHP install

robertoi · 2022-01-11T10:06:43Z

Hello everyone I'm new to the forum, and dont yet have a ASHP but have been very interested to learn about the technology recently, alot of it from Mars's website and this forum. I'm currently weighing up my options around installing a ASHP. I can't pretend this is purely environmentally driven as I would like to save money ultimately, ideally whilst also eventually stopping using gas entirely and reducing my CO2 footprint... I have been doing some calculations and from what I can tell it only really makes financial sense for me to go for a ASHP if I also install PV panels at the same time. In order to convince my better half of the pros of this it would be nice to say how quickly the install would become cost neutral. To try and estimate this I need to have a guess at what my COP is likely to be... I have a 135m2 detached 1990s house with loft and cavity insulation, and double glazed windows throughout. We currently have 14 radiators, although I am considering getting rid of the downstairs rads and switching to UFH throughout. As we are having an extension built shortly we had SAP calcs done which suggest a total space heating requirement for our house of around 11500kwH per year, plus probably around 4000 for hot water - which matches quite closely my annual gas use of 15500 kwh last year. I wanted to get an idea of what kind of average COP I might achieve over the course of the year. Am I being too optimistic to think that I might achieve a COP of 3.5-4, particularly if I move to UFH??? What sort of avearage COP are other forum members getting from their systems??? Many thanks in advance! Rob

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Air Source Heat Pumps (ASHPs)

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robertoi

(@robertoi)

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Topic starter 11/01/2022 11:18 pm

Thankyou for all the advice - certainly food for thought - and apologies for precipitating an argument!

On reflection on what you've said @derek-m I am now leaning against the idea of an ASHP at this stage.

To be honest two things got me thinking about this again recently - firstly an ill informed (in my opinion......we shall see) plumber saying they thought I needed to replace my 4 year old boiler (some nonsense (IMHO) about under floor heating needing higher heat output - from what Ive read this is likely to be the exact opposite), and thoughts of replacing our boiler now when I could 'future proof' against rising gas prices by moving to electric heating.

However as you say Derek, I'd need to achieve an average COP over the year of 4 at least to break even let alone save money (based on my current albeit very generous energy tariff....that wont last!).

I think for now I'll stick with gas and see what energy prices/ the cost of the pumps do over the next couple of years.

However your comments HAVE made me go back and have another serious look at solar on its own - and I think thats the direction Im going to head in - we ought to easily be able to use all the power we can potentially generate and break even in about 6-7 years based on current available electricity prices - so THANKYOU for focussing my mind! Less rush to get that sorted too seeing as theres no grants.....grrrr

@majordennisbloodnok I am seriously impressed by the price you got your system for - was that a solar streets set up by any chance? I attended a talk by them here last year but as far as I can tell there wasn't really any take up which is a real shame. However EoN's packages dont seem too bad at present....

This post was modified 4 years ago by robertoi

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batalto

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11/01/2022 11:41 pm

@robertoi PV on its own can be massively beneficial. Tied in with a battery and it can be even better. Last year with generation and energy savings I saved about £1800; £600 in generation and the rest from solar meaning I didn't need to buy power.

People seem to assume that buying PV adds cost. I've had my system two and half years and it's paid back 33% of the install costs. At the crazy unit rates this year coming, that'll be even greater. Adding as ASHP just means my heating and water bills will be around zero for 6 months of the year, lowered in 3 months and higher in the winter three months. However I am happy as it's an offset game.

For an FYI my solar and battery cost £11,800 and my ASHP (which replaced mains gas) was £5000 - but I'll get this all back in RHI. I am hoping my heating bills are a little lower. My energy use certainly is far far lower than it would be by burning gas and as such my CO2 will be dramatically lower.

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE

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Majordennisbloodnok

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11/01/2022 11:58 pm

@robertoi, no it wasn’t them. In fact, it was a partnership between Surrey County Council and Solargaps. The council got the public interest, Solargaps negotiated the bulk buy deal with the manufacturers and then they held an auction to find an installer to handle the logistics. The preferential prices basically brought the cost down to the point that I effectively got the battery for free.

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; sumus solum profundum variat"

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Majordennisbloodnok

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12/01/2022 8:08 am

Posted by: @majordennisbloodnok

@robertoi, no it wasn’t them. In fact, it was a partnership between Surrey County Council and Solargaps. The council got the public interest, Solargaps negotiated the bulk buy deal with the manufacturers and then they held an auction to find an installer to handle the logistics. The preferential prices basically brought the cost down to the point that I effectively got the battery for free.

My bad, too many companies with similar names. Not Solargaps but Solar Together. Apologies.

"Semper in excretia; sumus solum profundum variat"

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