GSHP - I need help with making it as efficient as possible!

countryhouse39

We have a GSHP for our heating and hot water. the RHI payments end this year and so we have the double whammy of no longer getting that alongside rising energy costs, and its worrying me. Our GSHP was installed by previous occupants of the house who then got divorced and sold house to us shortly after completing the works (I sometimes wonder if the stress of the heating system aggravated any problems they were having!) The reason why this is relevant is that in all the time we have been here we have had lots of issues with it and the main stress we have is that there are so few people in our area willing to service / repair it or any part of the heating system, that any time anything goes wrong it take a lot of time and money to fix; so much so i am seriously contemplating retraining as a renewables engineer!!

Anyway, we are lucky that we have a lovely big house (5bed,3living) but this means our energy use is high. Despite being resigned to our usage being higher than average, I still feel that its also higher than it should be, even taking the size of property into account. During winter we regularly use 100kwh a day, and we need to bring this down. I am hoping there is someone on here who can help me identify where/how we can make things more efficient. Thanks!

Rodders53

A long top sticky thread here https://forums.moneysavingexpert.com/categories/lpg-heating-oil-solid-other-fuels worth a read first.

Then people will need more details of the system installed, make model, UFH?,  zones, radiators, hot water, floor areas.  Insulation, double glazing etc.,.   Inc stuff like the EPC estimated heat / hw demand, and your own measured electric use...  Plus boler controls and how you've set them at the moment.

Insulate, insulate, insulate and Draught-proof are the starters.  Ensuring HP backup immersion heaters are not used a must.  Suitably low circulating water temperatures for better CoP etc.,.

EDIT RHI on GSHPs was for 20 years???  So your install is presumably very old, now?

Verdigris

I would strongly advise reading Heat Pumps for the Home by John Cantor, to acquaint yourself with best practise, and see what you can do yourself to optimise operation. At your present consumption employing a consultant to look at the system could be a relatively small cost that could yield significant savings.

You don't say anything about the house, except that it is relatively large, and, as Rodder says, looking to improving its energy is key to reducing consumption. What does the EPC say the energy consumption ought to be? You can look your EPC up online, if you don't have it to hand.

matelodave

Rodders53 said:

EDIT RHI on GSHPs was for 20 years???  So your install is presumably very old, now?

not true = RHI wasn't actually implemented until 9th April 2014 and was only for seven years althou GSHPs that were installed back to 2009 were eligible 

more info here - RHI - Renewable Heat Incentive Domestic | RHI Domestic | Renewable Heat Incentive | Renewable Heating | Ground source heat pumps (gshp.org.uk)

countryhouse39

Thanks for replies. Will have a look through the thread you suggested. Regarding the age of the heat pump its was installed in 2012. The previous occupants didn't even know about the RHI payments they could get so when we bought the house we applied and have been having them almost 7 years now and I'm sure that it said 7 years only, but I will double check!

Its a vaillant heat pump - 10kW geotherm. we have UFH downstairs (off 2 separate manifolds) all of which have room thermostats, and rads upstairs. Our EPC from just after we bought the house reckons we are a band C(73) and that our 'heat demands' are just under 40,000kwh for heating, 3000kwh for water. We use around 20000kwh a year which I think means that the COP is only about 2...when it should be better than that?

It is an old house that was extensively 'modernised' by the previous owner, however they left rolls of insulation uninstalled in the loft etc, but since we moved in we have installed more insulation, replaced most of the single glazing with double (at great expense as its a conservation area so very particular requirements!) and also changed the settings on the pump as when we first moved in they had the immersion heater on all the time (!) which meant we got a horrific first months bill as it was in the winter!

Verdigris

Having UFH is a good start, provided it was properly specified and installed. You ought to be able to meet demand with a flow temperature of 35 degrees, which should give you a COP of at least 4.

Have you any way of knowing how big the ground collector coils are? If they're too small you'll be creating a permafrost.

countryhouse39

I don't know exact info on the ground collector but its a very deep borehole that the last person to come out and look at it all said was more than big enough.

Verdigris

Ah, with you moniker I'd assumed large grounds that could accomodate ground coils. A properly specced borehole won't be the problem.

Do you know what the flow temperatures are set to?

countryhouse39

just looked at all the info on the pump:
on the 1st menu screen it currently says:
Flow temp CH: 46deg
system pressure 1.9 bar
brine pressure 1.4 bar

2nd menu screen says:
Parameter Heating
operation mode 
Auto
set value day: 21deg
night set back temp 15deg

Then
Dometic Hot water
Parameters
operation mode Auto
Min DHW temp: 43deg
current DHW temp: 50deg

Reed_Richards

If you got the RHI you should have an MCS certificate for your installation.  On the certificate it should tell you a flow temperature and an SCoP (Seasonal Coefficient of Performance) - or at least mine tells you this.   It would be helpful to know what these are (and whether the flow temperature currently being used is the same as on the SCoP).

countryhouse39

I should add that our house is def not boiling hot..! Bedrooms (where we have rads) are relatively cottagey in size and volume, TRVs keep these at approx 20deg for the kids rooms and 19 for ours. Downstairs we have 2 average sized livingrooms and an office and one large volume space (large kitchen diner with very high ceiling) which are all UFH. The kitchen only ever goes above 21 degrees when its bathed in sunshine in midsummer.