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Ground source heat pump is unaffordable to run

GSHPwoes · 2024-01-25T14:18:56Z

Hi - I have joined this forum after a web search as I am looking for some help with why our GSHP is costing us so much money. It was installed a while ago (we've been in the house almost 9 years and the previous owners were the ones to install it a year before that) and we have tried to get to grips with what is going on for a long time, but its now reached a point where electricity prices are so high we may have to leave our house as we cant afford to run it! We are a family of 5 and it is a large 5 bedroom house, originally early 1900s building but was extended and upgraded by prev owners. The pump is a vaillant GSHP and we arent on gas network so it heats out hot water too. Our house is rarely warmer than 19 degrees unless its a warm summer day. We have underfloor heating downstairs and radiators in the bedrooms upstairs. The living spaces are quite large, but bedrooms are relatively small (cottagey size). Our electricity usage in December was 2200kwh and I know it is mostly down to the heat pump rather than some electricity guzzling machine left on... We cannot afford this level of usage at the prices we have, especially when we have turned all the thermostats down to ask for no more than 18 degrees. Has anyone got any advise on why our heat pump is so inefficient? Thanks!

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Ground Source Heat Pump (GSHPs)

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Derek M

(@derek-m)

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Joined: 5 years ago

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25/01/2024 10:02 pm

Posted by: @gshpwoes

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@kev-m the v hot water isnt all the time - was just when we had the cold snap - the hot water out the tap was really hot, despite the fact the rads were barely warm. but sometimes its not hot enough... ug. we do have a an immersion that was on the first week we moved in, and our bills were astronomical(even back with low kwh prices!) so i know it is definitely not on now as we switched it off. House is approx 300m2, so it is large, but i know people with much larger houses using a lot less kwh than us...

I would look for a 3-way diverter valve or two 2-way valves that divert the warm water from the heat pump to the central heating or DHW cylinder. It is possible one of the valve/s is sticking intermittently.

Please provide some photo's of your system.

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HughF

(@hughf)

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25/01/2024 10:10 pm

Posted by: @gshpwoes

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@hughf we are purely electric no gas. our kwh per year was approx 20,000kwh but last year was just over 16,00kwh...

if we assume 18000kWh, that’s a 3kW immersion heater, on for 24hrs a day, for 250 days…. Are you sure you aren’t running on the backup heater in the buffer tank?

Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.

My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.

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GSHPwoes

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Topic starter 25/01/2024 10:12 pm

@derek-m what photos would be helpful - i can take them tomorrow.

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GSHPwoes

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Topic starter 25/01/2024 10:12 pm

@hughf i dont think so, the immersion switch is definitely off, but how can i check?

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GSHPwoes

(@gshpwoes)

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Topic starter 25/01/2024 10:13 pm

thank you for all your replies and sorry im so clueless - im embarrassed i know so little after so much time!

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Mars

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Posts: 3772

25/01/2024 10:22 pm

@gshpwoes, there is absolutely nothing to be embarrassed about. These systems should just work, and for the geeks these systems allow us to geek out further, but it’s frustrating when they’re inherently broken. If you continue to struggle and would like a pro like @heacol to come out and investigate, I can connect you.

Get a copy of The Ultimate Guide to Heat Pumps

Subscribe and follow our Homeowners’ Q&A heat pump podcast

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Derek M

(@derek-m)

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Posts: 4427

25/01/2024 11:53 pm

Posted by: @gshpwoes

↑

@derek-m what photos would be helpful - i can take them tomorrow.

Wide view of the different parts of the system, then close-ups of individual items of equipment, along with screen displays from your controller showing anything of importance.

Basically the more information the better.

Locate your diverter valves or valves and see if you can check operation by initiating DHW heating then back to central heating. Check the temperature of the pipework around the valves and buffer tank or low loss header.

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GSHPwoes

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Topic starter 26/01/2024 12:05 pm

Hopefully photos are attached…

This post was modified 2 years ago by GSHPwoes

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GSHPwoes

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Topic starter 26/01/2024 12:06 pm

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HughF

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26/01/2024 12:11 pm

6kW immersion in the bottom of the hot water tank won’t be helping things….

Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.

My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.

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HughF

(@hughf)

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Posts: 489

26/01/2024 12:13 pm

Why are you running your rads at 46 degrees in this weather? That seems excessive.

Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.

My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.

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GSHPwoes

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Topic starter 26/01/2024 12:17 pm

@hughf - we aren’t on purpose - they certainly don’t feel hot. I should add the system does an extra heat of the HW on a Friday for legionella prevention?

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