ASHP on a low incom...
 
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ASHP on a low income: a cautionary tale

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(@zoomuno)
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140 kWhs
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This is a 'cautionary tale' for anyone thinking of getting an ASHP who is on a fixed low income and/or uses their current means of heating very sparingly. I was lucky enough to get a Green Homes Grant which covered most of the installation cost and had expected the running costs to be simlar (or possibly even a little less) than a gas combi boiler. What I hadn't grasped though was the very different way it mean of heating my house. Previously, because my income is very small, I ran the heating only when absolutely needed (and generally less than was really needed for health); with the ASHP, the advice is to leave it on 24/7 at a constant (or near-constant) temperature. Even before the worst of the utility prices leap, this saw my bills tripling last winter. This winter, my plan is to keep the temperature as low as I can in order to minimise the risk of the house becoming damp and then to wear multi-layer thermals, hot water bottles, spend more time in bed, etc. This would have been so even if prices hadn't surged, but even at the heating level I'm now looking at, I have no idea how I'm going to cope financially from this point on. I'm not advising anyone else not to get an ASHP, but if you heat your house in a similar way to me pre-heat pump, think very carefully about what the 24/7 might mean in practice.


   
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Mars
 Mars
(@editor)
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Thanks for sharing your experiences @zoomuno.

Was this (running the ASHP 24/7) explained to you when you purchased the heat pump, and did you get a breakdown showing comparative running costs between gas and the ASHP? Is your house well insulated? 

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(@zoomuno)
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Topic starter  

Thanks, Mars. The 24/7 things was explained to me when I purchased. I would say the breakdown made many assumptions about how the house would usually be heated (without making them explicit). I've refined my usage after reading a lot of posts here (thank you!) and taking advice from Midea. House is very well insulated. I'm not sure I can do much else (though open to suggestions).

Whilst I read up on heat pumps (pros and cons), I ultimately didn't grasp what it would mean in the day to day usage, and perhaps I couldn't have done fully without this practical experience. I do regret going ahead (and regret reaching that conclusion because I very much want to move towards more sustainable living). I'll see how this winter goes, but I might end up borrowing money to install a gas boiler again (and can hardly believe I'm having to consider this!). Obviously the dramatic increase in fuel tariffs has made things much worse (for everyone) and I wouldn't say to someone else in my position that they shouldn't go ahead. However, I'd advise them to be wary that there seems to be no information out there on the implications for people who are on low incomes (benefits/minimum wage/precarity, and with no possibility of improving their financial circumstances).


   
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(@kev-m)
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Posted by: @zoomuno

Thanks, Mars. The 24/7 things was explained to me when I purchased. I would say the breakdown made many assumptions about how the house would usually be heated (without making them explicit). I've refined my usage after reading a lot of posts here (thank you!) and taking advice from Midea. House is very well insulated. I'm not sure I can do much else (though open to suggestions).

Whilst I read up on heat pumps (pros and cons), I ultimately didn't grasp what it would mean in the day to day usage, and perhaps I couldn't have done fully without this practical experience. I do regret going ahead (and regret reaching that conclusion because I very much want to move towards more sustainable living). I'll see how this winter goes, but I might end up borrowing money to install a gas boiler again (and can hardly believe I'm having to consider this!). Obviously the dramatic increase in fuel tariffs has made things much worse (for everyone) and I wouldn't say to someone else in my position that they shouldn't go ahead. However, I'd advise them to be wary that there seems to be no information out there on the implications for people who are on low incomes (benefits/minimum wage/precarity, and with no possibility of improving their financial circumstances).

As long as you have correctly sized radiators it's a bit of a myth that you have to run an ASHP 24/7. (if you have underfloor heating it's different). 

An ASHP does lose efficiency when you heat the water/let it cool repeatedly but it's not that much. My ASHP is off 12-5am and that is definitely cheaper than running it all night.  My house heats up quite quickly in the morning. Having your heating varying by about 5 degrees, say between 15 and 20C is fine for an ASHP.  If your heating cost tripled there might be something else going on. 

Do you know how your ASHP is set up; for example, how is the radiator flow temperature controlled and what temperature is your hot water (and how much do you use)?

      


   
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(@zoomuno)
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Topic starter  

Thanks @kev-m. So would you switch off at night at any time of the year? In winter, my house would cool a lot if I switched off overnight, so I'm guessing the ASHP would have to work very hard during the day and might take most of the day to get to a reasonable temperature (and might take several hours if I lowered it as much as 5 degrees at night). Last winter, I most aimed for a daytime temperature of 16 or 17 degrees because of cost (not good with chronic health condition :-/ ) and 14-15 at night (but pump kept coming on during night and I found the temp too high).

The rads have been confirmed as correct size. Do you know how I can check rad flow temp control? Hot water temp is at 45 degrees. I use very little: wash up once or twice a week; shower less than average (chronic health again as opposed to bad hygiene!), but also  keep hot water use to minimum (rinse hair on cold). Ridiculous really to be in this position! It would be lovely to  find a way to keep the house warmer, but it's reducing the overall bill that's the priority in hopes I can avoid going back to gas.


   
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(@prjohn)
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@zoomuno Have you had your radiators balanced, this can contribute to the high usage if incorrectly balanced. Balancing reduced my consumption significantly.


   
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(@kev-m)
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@zoomuno 

Yes to switching off all year.  My house drops from 20C or so to 15 overnight in the winter.  My house is quite well insulated but only to 1990 standard with a bit extra loft insulation.

What make, model and kW rating ASHP do you have?  If you tell us someone will probably be familiar with it. Also, what size and age is your house? Do you know if your ASHP is working on weather compensation? If it is then the rads will be hotter when it's colder outside.  That's normally the most efficient way to run an ASHP.  Are your radiators ever hot as in too hot to comfortably keep your hand on? 

45C is about right for water for most people; ours is 47.  Rinsing hair in cold is only going to save pennies; it's heating and/or lots of long baths and showers that rack up the pounds.  

I do feel for you and hope you can at least be comfortable. If it's any consolation (and it probably isn't) at today's prices I doubt gas CH would be much cheaper to run.


   
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(@zoomuno)
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140 kWhs
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Topic starter  

Thank you @prjohn I'm pretty sure they were balanced at the time of installing, but I'll definitely look into this.


   
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(@zoomuno)
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Posts: 23
Topic starter  

@kev-m Wow, that's interesting (the switching off). I'll experiment with that come autumn.

The pump is a Midea monobloc model MHC-V10W/D2N8-B. Heating capacity says 10kW. House is three-bed semi (cavity wall insulated and well insulted loft), built 1948 but with 2022 timber built single-storey extension (insulated to max). Yes, pump is working on weather compensation. Radiators are never hot, at most luke warm in winter.

Thanks so much for your response. I'm wowed by the knowledge and generosity on this forum!


   
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(@kev-m)
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@zoomuno 

It sounds as if you have the basics right.  Have a look at these threads that discuss Midea ASHPs.

https://renewableheatinghub.co.uk/forums/renewable-heating-air-source-heap-pumps-ashps/midea-mhc-v16-new-install#post-6799

https://renewableheatinghub.co.uk/forums/renewable-heating-air-source-heap-pumps-ashps/14kw-midea-ashp-in-an-old-leaky-building

There are some links/references that may be useful. 

What does your EPC say for the energy and hot water consumption for your house?  It can be useful to give a rough estimate of how many kWh your ASHP is likely to consume in a year.  


   
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Jeff
 Jeff
(@jeff)
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I would be tempted if only for interest to work out how much your old mains gas boiler would have cost to run given the dramatic increases in gas prices, even higher in percentage terms than the increases in electricity prices.

Do you know what your annual consumption was for gas in kWh when you use to have a gas boiler? 


   
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(@zoomuno)
Trusted Member Member
140 kWhs
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Topic starter  

Hi @jeff So my dual fuel costs for 12 months to October 2021 was £373. (My bills were extremely low compared to most households, but that kept it affordable.) My utility company (electricity only now) now wants to put my DD up to £165/month (I've resisted, but there's a debt building so I'm going to have to bite the bullet). That difference, if my maths is right and taking into account a price hike of 54%, has a little more than trebled the original costs, but I have a few additional costs since then that account for that extra.


   
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