Ground Source Heat Pumps

poohbear59

Patrol said:

Thanks for your figures, I can't see anything that looks terrible. In my non-expert view;

• For 2.2 I would expect it to be 7d if you wanted to increase the temperature once a week
• 4's and 5's look OK I think
• 8 being 120 minutes looks fine. Mine was set to 60 at installation and I changed to 180. If you see additional heat being used 2 hours after the pump starts a cycle you could consider increasing it. Do you know if your unit runs for longer than 2 hours at a time?

7.3
471 hours over 11 years is about 0.8 hours a week additional heat. Each hour (at 5.5's 2/3 setting) uses 6kW of electricity. Reducing the water peak frequency should reduce additional heat a bit.

7.1 + 7.2
The manual suggests a heat curve of 4 to 6.5 for a property with radiators, you have a setting of 5 which seems reasonable but the property is cold downstairs and hot upstairs. I'd probably check the downstairs radiators are fully open and those upstairs are slightly closed and tweak a bit each day until happy or until you can get thermostat controls. If downstairs is still too cold you could increase the heat curve to 6 but generally speaking this will increase the running cost. At that point if the house has never been warm enough you might want to check if there are enough suitably sized radiators downstairs.

Thank you for taking a look for me and for the advice. I will go through all of the steps you recommend and will let you know how/ if things change. 

ccbrowning

Does anyone here have a Heliotherm unit? I feel like my electricity use is high. However, I just turned it to 'summer' mode today after finding a half-baked English operator manual, so at least it will only be running for DHW. I swear even with all thermostats set to like 12C and the thermostats reading 20 ambient, the thing was still running the heating.

Four examples of energy usage in a 4 bedroom modern home, only underfloor heating on both floors, and 2 adults living in it (moved in mid Feb this year):

• 14/06/2022 434 kWh
• 14/05/2022 480 kWh
• 14/04/2022 357 kWh
• 30/03/2022 1014 kWh (actually covers six weeks tho)

We have a 3.41 kWh PV installation, but that doesn't do a lot when it's cloudy of course. It also has a World Heat Climacyl, 200L Capacity and another grey tank with no labels next to it which looks maybe 100-125L.

Reed_Richards

ccbrowning said:

 all the radiators set to like 12C ... only underfloor heating on both floors, 

I don't understand, "only underfloor heating" implies no radiators.

ccbrowning said:

... the thermostats reading 20 ambient, the thing was still running the heating.

My house needs it to be about 15.5 C outside to maintain an ambient of 20 C inside without heating.  Where I live in the north of England the average outside temperature has been less than that until quite recently.  But if you were trying to maintain an ambient of 12 C I guess you have not mastered the controls.

ccbrowning said:

We have a 3.41 kWh PV installation, but that doesn't do a lot when it's cloudy of course.  

It would do most for you if you time the DHW heating to come on for an hour or two (as necessary) in the middle of the day.

ccbrowning said:

 another grey tank with no labels next to it which looks maybe 100-125L.

That would be the buffer tank; heat pumps seem to need these, don't ask me why.

I used to have an oil boiler that provided all heating and hot water and my electricity use was about 8 kWh per day.  My ASHP used 17.2 kWh per day on average in April, 6.1 kWh average per day in May but we were away for 9 days so that distorts the average.  These figures do not include all my DHW heating on sunny days when i use solar power direct to my immersion heater.  

ccbrowning

Thanks, @Reed_Richards. I meant to type thermostat not radiators. We have Salus ones for each zone.

Summer mode has indeed made it not turn on the heating luckily. We have a meter that shows us only heating electrical usage and it hasn't gone up at all since I changed the mode. Just obviously need to turn it back to automatic when it gets cool again. The thermostats have definitely been showing a temperature of 18.5/19 even on like 12C days, but the real test will be now that I 100% know heating isn't going to kick in.

Regarding timing the DHW heating to come on in the middle of the day, I just looked and the default setting is supposed to be on from 0500 to 2000 but they actually changed it to 0000 to 2400?!?. The original installers of the GSHP don't understand solar - no one even installed an iBoost or Eddi even though it was built from scratch as an eco home with solar + borehole GSHP. 

Reed_Richards

ccbrowning said:

Regarding timing the DHW heating to come on in the middle of the day, I just looked and the default setting is supposed to be on from 0500 to 2000 but they actually changed it to 0000 to 2400?!?. The original installers of the GSHP don't understand solar - no one even installed an iBoost or Eddi even though it was built from scratch as an eco home with solar + borehole GSHP. 

If the installers don't want their customers to ever complain that their hot water isn't hot enough then they set the heating function to be on all the time.  If you, the householder, don't want to waste money on heating your hot water (and you keep regular hours) then you turn off the heating function overnight, hence the default setting.  Although you can heat your water with a lot less electricity using your heat pump, if you want to heat it with free solar electricity then the power requirements of an immersion heater are better matched to the power output from a typical solar installation and an iBoost or similar allows you to send any spare power to your immersion heater, even if this is less than the 3 kW it would draw under normal circumstances.  But if you don't have one of those, time your DHW heating as I suggest.

I wonder if your system maintains the buffer tank at some minimum temperature for the eventuality that you might turn the (underfloor) heating on, hence the power draw even when there is no demand from the thermostats?  "Summer Mode" then turns this function off?    

ccbrowning

That makes sense! It's just two of us who ever need hot water for washing up ourselves or dishes. In terms of actual hot enough water for a shower, we can definitely try and time it to save money.

I spoke too soon on energy usage - even in Summer mode, it did use 1 kWh overnight for heating (but 0 the night before). So it does indeed do some work occasionally. Perhaps I should also set the timer on that one as it is also 0000-2400.

Patrol

Reed_Richards said:

That would be the buffer tank; heat pumps seem to need these, don't ask me why.

Buffer tanks allow a greater volume of water to be available, the heat pump will take longer to heat it up each cycle but the intention is to reduce "cycling" i.e. the heat pump doesn't switch on and off so often. Also, the GSHP's I'm familiar with expect at least 70% of the heating circuit to be available so I think a buffer tank works in the scenario where thermostats reduce or stop flow around the heating circuit.

It's a pity lovesgshp no longer appears to be active as no doubt he could explain it better.

ccbrowning it is likely your GSHP allows you to see how many hours are used for domestic hot water and for heating which might give different results to your meter. e.g. on this manual section 5 mentions it while other readings might also be of interest.

https://www.heliotherm.com/media/reglerbeschreibung-kundenebene-englisch-mail.pdf

ccbrowning

Patrol said:
ccbrowning it is likely your GSHP allows you to see how many hours are used for domestic hot water and for heating which might give different results to your meter. e.g. on this manual section 5 mentions it while other readings might also be of interest.

https://www.heliotherm.com/media/reglerbeschreibung-kundenebene-englisch-mail.pdf

Yes I have this manual, but it is actually incorrect in how the interface seems to work, as when I set off-on values I don't see a change in the grey and black bars. Also, the first setting entry doesn't even let me change the 00:00 start, so I am trying with a 00:00 off 07:00 first entry and then a number of others after it. But you still end up with like 5 entries you can't remove and say 24:00 off 24:00 or something wild.

JHen1

Bit of an emergency - found my GSHP making a funny noise and noticed the fluid tank was empty - I filed this up twice with glycol and water but it kept emptying. I then noticed that the fluid was gushing out of  the fitting. I tried to tighten by hand but no luck. Can I assume a washer has failed ? Should I keep the heat pump of until fixed. I'm use Alto Energy so that could be some time - could I use "any" heat pump engineer to fix ? If I get the part myself from some where can I assume lots of fluid will come out ?

Mister_G

Looks like a pretty standard MDPE 40/32mm reducer.  Available from any good plumbers merchant, or here: https://www.ebay.co.uk/itm/125272322783?hash=item1d2acff2df:g:LIgAAOSw5~5iYRWd&amdata=enc:AQAHAAAA8PaDiIWMfM4lu/p54ck7pYEzXarIW/3BUHt4E0DhIzPM/nUiXRMEloctRMerD1KftcXjSOZN6Nsnjh6qQRM1hQS1TmwQ7BZrsf7e0I0FL4bSMtceXuLNm2r39h0pWuTd3Ya+L0MiDgz+vIHRXlSUZbDrvOW6/agnw0BRbjxbN24B1OVbuZ3PPh2ykJUvG5sbm9OBU9dDr3F8UrGorPaOI3SaKUMUNUXt8M16azjOFjwTmuKbCs3NRCfU8lFUkrqZ8wg2mGbrHZ6K5rFr1gRBLEMzieOypuY3x3r88TfrpBHeacMG5j4/2hAeMi3Y4Cv0FQ==|tkp:BFBMiuKO2r9g