Navitron Renewable Energy and Sustainability Forum

HEAT PUMPS & Geothermal Energy => Heat Pumps => Topic started by: davec on February 01, 2014, 09:57:59 AM



Title: One year in... some GSHP numbers
Post by: davec on February 01, 2014, 09:57:59 AM
When we started looking into ground-source for our house renovation, it was difficult to find any 'real' examples to help specify a system and estimate expected performance. Now we've been living with it for a year, here's some numbers.....

The original building is stonebuilt, renovated with -200mm wood-fibre EWI and modern wood-clad extension; roof insulation also -200mm wood-fibre. Ground floor around 160sqm with 150mm kingspan, wet UFH and -170mm screed; upstairs around 125sqm with just normal-sized radiators run at the same temp as the UFH. We have 300 litres unvented DHW with 40*ET solar thermal, 55degC Heat-pump feed and 60degC immersion inputs. We also have 2kW of PV. EPC shows estimated annual heating = 16552kWh, DHW = 1749kWh.

Heat pump is rated 9kW with a 2kW draw; source is a single borehole; there's a 100L buffer tank. We have an Economy-10 supply and fitted extra meters to monitor immersion and GSHP.

Total import 8631kWh (3412 high-rate, 4949 low). GSHP heating accounts for about 50% of this (4420); DHW about 10% (Immersion 650 plus heat-pump 216); the remaining 40% is cooking, light, appliances, kettle....

I hope this will help others trying to do realistic sums....

Davec.
 


Title: Re: One year in... some GSHP numbers
Post by: regen on February 02, 2014, 09:33:29 AM
Hi Dave,

Are you achieving about 4 to 1 on the GSHP and heating a 285m2 house for about £500 or is my interpretation a bit out.  If so seems an excellent result. 

Regen


Title: Re: One year in... some GSHP numbers
Post by: daserra on February 02, 2014, 11:52:00 AM
The renovations sounds like the perfect type for a heat pump, highly insulated, large thermal mass in the UFH and ground source not air source. How deep and wide is the borehole?


Title: Re: One year in... some GSHP numbers
Post by: davec on February 02, 2014, 04:47:04 PM
Quote
Are you achieving about 4 to 1 on the GSHP and heating a 285m2 house for about £500 or is my interpretation a bit out... 

Aye, annual efficiency over 3.5, if the EPC estimate is accurate... total electricity cost for last year was £1075; heating accounts for about £550.

Quote
How deep and wide is the borehole?

220m deep, 115mm wide with 40mm flow and return pipes.

Davec.



Title: Re: One year in... some GSHP numbers
Post by: dhaslam on February 02, 2014, 07:25:01 PM
What range of input temperatures are you getting?


Title: Re: One year in... some GSHP numbers
Post by: clockmanFR on February 02, 2014, 07:32:35 PM
Hi davec.

Really interested in:-

Maintenance costs and offset budget for replacement?
Embedded costs, ie cost of install if done commercially.?


Title: Re: One year in... some GSHP numbers
Post by: oliver90owner on February 02, 2014, 08:31:47 PM
Wow, that is some deep hole!

Or did you mean 67m?

RAB



Title: Re: One year in... some GSHP numbers
Post by: davec on February 02, 2014, 09:03:51 PM
Quote
What range of input temperatures are you getting?

HP displays return temp rather than input temp. This shows 9degC at rest and 5degC when running. I've not noticed any seasonal variation.

Quote
Maintenance costs and offset budget for replacement?

So far no maintenance except check pressures which I can do. Heat pump should be good for 20 years, replacement cost is not too scary; borehole is more scary but should be good for 50.

Quote
Embedded costs, ie cost of install if done commercially.?

Can't really disconnect these costs from the overall renovation job which was very much driven by the renewables.

Quote
did you mean 67m?

No, 220m, see "Boring" in this topic for more info.

DaveC




 


Title: Re: One year in... some GSHP numbers
Post by: daserra on February 02, 2014, 09:25:05 PM
Very deep (and expensive) hole I should imagine. Did they line it with anything? The deepest water borehole I've organised here was 320m and that cost the price of a new car !


Title: Re: One year in... some GSHP numbers
Post by: clockmanFR on February 02, 2014, 09:44:32 PM
"Can't really disconnect these costs from the overall renovation job which was very much driven by the renewables".

That's a shame.

 Would liked to have known true embedded costs and therefore true heating costs. Cost of bore hole?, cost of pipes and fittings?, circulation pump and its motor kW,? the heat pump unit itself and its power draw?, tanks that are needed and other embedded costs.?

Would be nice to compare to my underfloor 3kw electric heating matts that heats my main house, it has minimum embedded costs of about £400, including thermostats and my auto circuits. Electric is from my Turbines and PV.


Title: Re: One year in... some GSHP numbers
Post by: titan on February 03, 2014, 01:10:23 PM

 Would liked to have known true embedded costs and therefore true heating costs. Cost of bore hole?, cost of pipes and fittings?, circulation pump and its motor kW,? the heat pump unit itself and its power draw?, tanks that are needed and other embedded costs.?

Would be nice to compare to my underfloor 3kw electric heating matts that heats my main house, it has minimum embedded costs of about £400, including thermostats and my auto circuits. Electric is from my Turbines and PV.

What about the embedded cost of your PV  and 2 ( or three) turbine installations and your time of course building your turbines and trackers plus the equipment needed welding machines  and consumables etc. Getting a true cost comparison would be difficult. Electric mat heating is efficient but expensive if mains electricity is needed.


Title: Re: One year in... some GSHP numbers
Post by: clockmanFR on February 03, 2014, 06:25:57 PM
Here we are titan,

5kW PV Sharpe seconds, 2kw Yingli, £2,600.
3 trackers £1800 for the 5kw PV. (includes all cables etc)
2 Mppt PV controllers, £750.

3off. 3.7m turbines at total £3,200.

1300ah 48v batteries, £1400.
3.7kW Inverter, £150.

u]Grand total just under £10,000[/u]

Commercially, depends on the greed and profit margins.

All stuff is available and is DIY and absolutely no need for specialist equipment. Aldi do a welder Tod and Biff have one , somewhere at £50?

My time? no I send the Mrs CM out to work nowadays.  ;D


Title: Re: One year in... some GSHP numbers
Post by: titan on February 03, 2014, 07:21:28 PM
I can give some costs for my GSHP and UFH

GSHP + 125ltrs antifreeze  £4500, 500M of 40mm geothermal pipe £500 fittings for manifold £150, Sand for surrounding pipe £600 ( not normally needed but my ground is mudstone UFH pipe manifold, controls, pump etc £2500 grand total £7750. I have my own JCB.

Energy  to run GSHP 1st Jan to 31st Dec 2013 providing heating all year and DHW 8 months 2507 kWh house is 240m2 within the heated envelope, Heating is only on ground floor but heats whole house. There is also 60m2 insulated but unheated basement where GSHP and utilities are.


Title: Re: One year in... some GSHP numbers
Post by: davec on February 03, 2014, 08:22:17 PM
Do you have any EPC or MCS numbers that would let you work out the annual efficiency of the Heat Pump?

Davec.


Title: Re: One year in... some GSHP numbers
Post by: titan on February 04, 2014, 09:48:20 AM
Do you have any EPC or MCS numbers that would let you work out the annual efficiency of the Heat Pump?

Davec.

I don't think the  EPC or MCS figures would be accurate enough to calculate a COP from. The EPC was needed for a PV installation, it gave 17,290kWh for heating. The MCS figure for the GSHP gives 14.400 kWh and my calculations give 16,229kWh for heating. I based my projected yearly figure on degree days from the local met office weather station ( 6km away)  but having checked their temperatures daily over the last 18 months find in winter that they are quite often 1-3 deg C colder than I see at night which may account for my higher calculated figure. The only way to calculate COP is with a heat and electric  meter, anything else is a guess. The figures above would give COPs between 5.7 and 6.9 which is clearly unrealistic.
This year has started well, the milder weather and ( possibly) some adjustments I have made to the GSHP have resulted is a 42% reduction over last January's figure.


Title: Re: One year in... some GSHP numbers
Post by: davec on February 04, 2014, 11:36:57 AM
Quote
The only way to calculate COP is with a heat and electric  meter, anything else is a guess. The figures above would give COPs between 5.7 and 6.9 which is clearly unrealistic.

Agreed, but the RHI will probably consider EPC / MCS estimates if there's no metered figures. We jumped through the hoops to make ours 'meter ready' but DECC's not been to fit one. Believe they're now hoping that folk will fit their own as part of an installer maintenance deal... not obvious to me what benefit that might bring?

Whatever, looks like you're not spending fortunes on heating which must be a very pleasing result!

Davec.


Title: Re: One year in... some GSHP numbers
Post by: sam123 on February 06, 2014, 04:52:19 AM
Some numbers from Finland. Results have been measured with Pollucom energymeter (google). Hope it translates well. Ask if you don´t understand something.

http://translate.google.com/translate?sl=fi&tl=en&js=n&prev=_t&hl=fi&ie=UTF-8&u=http%3A%2F%2Flampopumput.info%2Ffoorumi%2Findex.php%3Ftopic%3D12902.0 (http://translate.google.com/translate?sl=fi&tl=en&js=n&prev=_t&hl=fi&ie=UTF-8&u=http%3A%2F%2Flampopumput.info%2Ffoorumi%2Findex.php%3Ftopic%3D12902.0)

Summarum: Annual year-COP 3.8 with DHW. In Finland we can only dream 5 degree brine liquid  :'( It is one degree and 3% better COP.

Cheers, Sami


Title: Re: One year in... some GSHP numbers
Post by: davec on February 08, 2015, 10:06:47 AM
And two years in....

Year1, Dec-2012/3 was:-
Quote
Total import 8361kWh (3412 high-rate, 4949 low). GSHP heating accounts for about 50% of this (4420); DHW about 10% (Immersion 650 plus heat-pump 216); the remaining 40% is cooking, light, appliances, kettle....

Year2, Dec-2013/4 was:-
Total import 7845kWh (3226 high-rate, 4619 low). GSHP heating accounts for about 50% of this (3725); DHW about 10% (Immersion 636 plus heat-pump 144); the remaining 40% is cooking, light, appliances, kettle....

So, Y2 numbers a bit less than Y1. Possible contributers: room-stats reduced by 1degC, now 17; HP compensation curve reduced by 4degC; and the weather was generally a lot nicer.



Title: Re: One year in... some GSHP numbers
Post by: titan on February 09, 2015, 09:54:54 AM
I think last year was milder. I also dropped the flow temperature and increased the temperature differential between the cut out and restart temperatures as I thought there is a bit of an overshoot before the stat operated.

It is a 240 m2 heated envelope I increased the bedroom temperatures to 18.5 deg and the main living area to 21 deg. 2013 I imported 5118 kWh and the HP used 2507kWh last year I imported 3731 kWh and the HP used 1593 kWh. The HP is on 24/7. The house is all electric.

Kensa reckon that buried pipe systems get better for a few years after installation as the ground settles


Title: Re: One year in... some GSHP numbers
Post by: davec on February 02, 2016, 09:06:38 PM
And, three years in....

Year1, Dec-2012/3 was:-
Quote
Total import 8361kWh (3412 high-rate, 4949 low). GSHP heating accounts for about 50% of this (4420); DHW about 10% (Immersion 650 plus heat-pump 216); the remaining 40% is cooking, light, appliances, kettle....

Year2, Dec-2013/4 was:-
Quote
Total import 7845kWh (3226 high-rate, 4619 low). GSHP heating accounts for about 50% of this (3725); DHW about 10% (Immersion 636 plus heat-pump 144); the remaining 40% is cooking, light, appliances, kettle....

Year3 Dec-2014/5 was:-
Total import 7862kWh (3324 high-rate, 4538 low). GSHP heating accounts for about 50% of this (4221); DHW about 6% (Immersion 343 plus heat-pump 128); the remainder is cooking, light, appliances, kettle, MineCraft....So, Y3 numbers very much on a par with Y2. DHW was reduced by reprogramming the immersion timer to knock out one hour of on-time a day; also fitted a flow-limiter to my childrens' favourite shower (bad dad).


Title: Re: One year in... some GSHP numbers
Post by: marshman on February 03, 2016, 09:33:24 PM
Nice to see yet more numbers coming in.

In my case the EPC figure is a complete work of fiction. It quoted 30,546 kWh per year just for the heating. The installer calculated 11,515kWh. Based on the (nearly) 2 months the system has been running I reckon the Heatpump will use around 2000kWh per year including hot water production. So if I used the EPC figure I would end up with a CoP of around 15 which is clearly rubbish. My place is also an old brick/stone/rubble built place with parts dating back to the 1700's It has been renovated and is fairly well insulated. It is 240 sq m, detached and in a very exposed position.

I'll be back in 10 months time to give the full years figures, though as has been mentioned elsewhere the ground loop trenches are still settling so some improvement could be expected there.

Roger


Title: Re: One year in... some GSHP numbers
Post by: davec on December 15, 2016, 08:48:09 PM
And, four years in....

Year1, Dec-2012/3 was:-
Quote
Total import 8361kWh (3412 high-rate, 4949 low). GSHP heating accounts for about 50% of this (4420); DHW about 10% (Immersion 650 plus heat-pump 216); the remaining 40% is cooking, light, appliances, kettle....

Year2, Dec-2013/4 was:-
Quote
Total import 7845kWh (3226 high-rate, 4619 low). GSHP heating accounts for about 50% of this (3725); DHW about 10% (Immersion 636 plus heat-pump 144); the remaining 40% is cooking, light, appliances, kettle....

Year3 Dec-2014/5 was:-
Quote
Total import 7862kWh (3324 high-rate, 4538 low). GSHP heating accounts for about 50% of this (4221); DHW about 6% (Immersion 343 plus heat-pump 128); the remainder is cooking, light, appliances, kettle, MineCraft....

Year4 Dec-2015/6 was:-
Total import 8841kWh (3871 high-rate, 4970 low). GSHP accounts for about 50% (4504); DHW about 7% (Immersion 563 + heat-pump 97); remainder much as before.... So, Y4 numbers up on Y3 but not massively out of kilter given that the kids are staying up longer nowadays, leaving lights on and doors open...


Title: Re: One year in... some GSHP numbers
Post by: marshman on December 16, 2016, 11:51:22 AM
Mine has now been installed and running for 12 months. In my last post I guestimated an annual electric consumption of around 2000kWh.  This has turned out to be a tad optimistic, but not that wide of the mark.

Total for 12 months 2330kWh for the heatpump. That's heating a 240 sq m, 5 bedroom detached house in an exposed position and providing DHW.  It runs 24/7.

I am expecting this to reduce over the next 12 months as since being fitted I have replaced the old windows with triple glazed and also replaced/rebuilt the draughty front porch and fitted a less draughty back door & generally improved the airtightness of the building. I am also still tweaking the heat curve. At the end of November when we had the cold snap The house was getting too warm!

Interestingly the ground loops are still settling! Looked in the field last week and noticed another trench top has collapsed inwards. I think this is the last one!

Incoming temps from the ground loop started at 14 deg this year and rapidly dropped to 11 deg where they are now. Last season they dropped to 8 deg at the end of March but rose to 10 deg by May when the heating shut it self down.

Total electric consumption was 5700kWh for the whole house - we are all electric but do have 3.15kWpk of Solar PV.  I have a dual rate meter (Economy 7) but find it is cheaper to have a single rate electric Tariff.

Roger


Title: Re: One year in... some GSHP numbers
Post by: Mikel on December 16, 2016, 01:30:51 PM
We have had our GSHP installed in since March 2013, a 10Kw GSHP with 3*40m horizontally laid slinkies. The GSHP provides heating to oversized radiators and DHW to 50C in a twin coil 305L hot water tank, with solar thermal providing DHW as well. We have had an electricity meter fitted to the GSHP since 10th Jan 2014 and a heat meter fitted since end 0f January 2014, together with an experimental control system. We have had a wood burner in the lounge from August 2014.

The GSHP is heating a 3-bed bungalow of 145 sq. m (originally a 4 bed bungalow but we converted one bedroom into a dining room).

Since Jan 2014, the GSHP has used 4080 kWh of electricity and an expected further 300 kWh till 10th Jan 2017, giving an estimated annual consumption of 1460 kWh. For Winter 2014/5 (Nov-Mar), the GSHP gave a CoP of 3.49 and for Winter 2015/6 a CoP of 3.44. The current CoP calculation (Nov-15th Dec) gives 3.55, reflecting no doubt the higher ground temps.

The wood burner allows us to heat the rest of the house to a lower temperature of 16C most of the time, exceptions being any particular cold spell.

We are very pleased with the system and whilst no doubt that UFH would be better, we can get very good performance out of oversized radiators.


Title: Re: One year in... some GSHP numbers
Post by: brackwell on December 16, 2016, 01:38:03 PM
Very informative Mikel ,thanks


Title: Re: One year in... some GSHP numbers
Post by: dhaslam on December 16, 2016, 01:48:20 PM
I have been using mine a bit differently this year.   No heat from the stove to the buffer tank  so the  heat pump is providing all the underfloor heating and  consumption has reached  1200 kWh  which is about the same as previous full years.   It brings the annual electricity  cost for heating to about 400 euro  but that includes a temperature of  up to  23C in living area  and  20-21C  in bedroom area.   I am now contemplating removing the stove  and adding an air source heat pump.    The air source  heat pump  would be used during the middle of the day primarily  and should have an  input temperature  on average of 7C  in the three coldest months.  It would serve as an alternative source  if the other system failed  and  would save  depleting the seasonal store.  The  seasonal store would be used as the heat source at night when the weather is too cold for the ground loop.  The ASHP  should not add much to the annual running cost,  since the GSHP is already being used at day rates, but the alternative of replacing the stove  with another would add nearly 1000 in annual fuel cost.  


Title: Re: One year in... some GSHP numbers
Post by: ringi on December 16, 2016, 01:53:04 PM
Incoming temps from the ground loop started at 14 deg this year and rapidly dropped to 11 deg where they are now. Last season they dropped to 8 deg at the end of March but rose to 10 deg by May when the heating shut it self down.
Roger

Not that much better then running an air source pump in the day time.


Title: Re: One year in... some GSHP numbers
Post by: Mikel on December 16, 2016, 02:10:41 PM
It would be nice if someone with an ASHP has some data to post.


Title: Re: One year in... some GSHP numbers
Post by: DonL on December 16, 2016, 03:14:56 PM
Your wish is.....
"After two winters. a quick report on my ASHP performance.
9kW Panasonic Aquarea, three bed bungalow, heating only with over size radiators. Maintaining 17C background with a log fire most evenings.
First winter 1401.5kWh
Second winter 1149.5kWh
Excellent controllability and comfort. No faults/problems.
Very happy."
This year I've raised the background temperature to 18C in response to She. The system has just managed to maintain that without changing the control parameters.
Consumption so far this winter is 618 kWh so seems consistent with previous years
Don


Title: Re: One year in... some GSHP numbers
Post by: MR GUS on December 16, 2016, 03:35:50 PM
Thanks for the update Don!


Title: Re: One year in... some GSHP numbers
Post by: Mikel on December 16, 2016, 04:35:26 PM
@brackwell. You're welcome!

Don, thanks. Looks like a good system. Useful to see a well performing ASHP with oversized rads. I think it is really important to show that as there is a tendency to reject heat pumps unless delivering through UFH.


Title: Re: One year in... some GSHP numbers
Post by: rogeriko on December 16, 2016, 10:12:36 PM
Ground source heat pumps are a hot item right now. The RHI is paying 20p per kwh so they are basically paying your entire electric bill, we are installing lots right now.


Title: Re: One year in... some GSHP numbers
Post by: davec on December 17, 2016, 02:39:47 PM
Aye, the way I looked at it was: EITHER you get back the extra capital expense of the system in only 7 years; OR you get the electricity bill paid for the next 20+ years. Win-win? Even with flat energy prices, it still looks that way.


Title: Re: One year in... some GSHP numbers
Post by: ringi on December 17, 2016, 03:37:44 PM
Would anyone in the UK be fitting ground source heat pumps if the RHI payments were not more than for an air source……


Title: Re: One year in... some GSHP numbers
Post by: rogeriko on December 17, 2016, 07:10:25 PM
No-one would be fitting any type of heat pump without the RHI. Who wants to pay the high electric bills they generate.


Title: Re: One year in... some GSHP numbers
Post by: DonL on December 17, 2016, 10:04:20 PM
No-one would be fitting any type of heat pump without the RHI. Who wants to pay the high electric bills they generate.
less than £200/year for heating is high?
Don


Title: Re: One year in... some GSHP numbers
Post by: ringi on December 17, 2016, 10:18:37 PM
No-one would be fitting any type of heat pump without the RHI. Who wants to pay the high electric bills they generate.

If you don't have mains gas, and you don't want to spend your life looking after a fire, it is hard to beat a heat pump.   (Unless you want heat 24hr a day, then E7 storage heaters can work.)


Title: Re: One year in... some GSHP numbers
Post by: rogeriko on December 17, 2016, 10:20:57 PM
Your normal 4/5kw (electric) heat pump running for about 12 hours a day heating the house and water uses over £7 worth of electric per day. Thats why the RHI will pay you up to £6600 per year.


Title: Re: One year in... some GSHP numbers
Post by: DonL on December 18, 2016, 09:55:00 AM
Your normal 4/5kw (electric) heat pump running for about 12 hours a day heating the house and water uses over £7 worth of electric per day. Thats why the RHI will pay you up to £6600 per year.
It is misleading, to estimate running costs in this way. We need to look at the annual demand and the COP of the system.
The heat pump very rarely uses anything approaching full power; at least in the case of a modern well controlled heat pump it will match power consumption to demand.
If I did not run the log burner which is free for me except for chainsaw consumables and some very valuable sweat, and the house were heated to RHI levels, the annual heat demand is about 15000kWh.
Taking a fairly conservative overall COP of 3.0 the absorbed power would be 5000kWh. At 13.5 p/kWh that gives an annual heating bill of £675.
Don


Title: Re: One year in... some GSHP numbers
Post by: DonL on December 18, 2016, 10:11:44 AM

Don, thanks. Looks like a good system. Useful to see a well performing ASHP with oversized rads. I think it is really important to show that as there is a tendency to reject heat pumps unless delivering through UFH.
Mikel, you are absolutely right. I continually preach to people about how good a system it is, partly because of the controllability and comfort. By having low temperature radiators and the temperature being modulated in response to outside temperature you get accurate room temperature control with none of the thermally induced draughts which you get with conventional heating and controls. With our oil boiler, the thermostat would turn the boiler on the radiators get hot and once the thermostat was satisfied they'd go cold and then the thermostat ......... The result is a continual temperature variation of about 2C and this is what most people live with! With the ASHP and a decent thermostat the temperature is virtually constant and you can comfortably live with a temperature a degree or two lower. Subjectively the improvement is really significant.


Title: Re: One year in... some GSHP numbers
Post by: titan on December 18, 2016, 11:18:36 AM
Your normal 4/5kw (electric) heat pump running for about 12 hours a day heating the house and water uses over £7 worth of electric per day. Thats why the RHI will pay you up to £6600 per year.

The RHI for heat pumps is only available where mains gas is unavailable. The payment is to offset the high capital cost of installation. Running costs are comparable to a gas system on normal rate electricity. It is part of the governments commitment to reducing emissions. Just checked, a GSHP is actually cheaper to run than gas
http://www.nottenergy.com/energy_cost_comparison/


Title: Re: One year in... some GSHP numbers
Post by: Mikel on December 19, 2016, 10:08:25 AM
Don, we have an experimental control system installed as we volunteered for a DECC trial. We merely set the temperature we would like and the system sorts it out. I have programmed a schedule when we are In, Out and Asleep but in practice the system comes on overnight and during the day. We can program going away and it will turn off the heating and then bring the house back up to temperature for our return.

If you want to increase the temperature setting, the heat pump will run continuously raising the flow temperature quite high (up to about 45C) with long run times until the house reaches the new setting. It then just adds heat as required. We have far fewer heat pump cycles compared with the original system, which used weather compensation and set times of heating. This new system, as I understand it, takes the local weather forecast as part of its control system. Like you, we have a log burner and we normally set the thermostat to 16C for most of the winter and then boost for particularly cold spells.

In practice, we have a design SPF (as required by the RHI) of 3.1; the original control system gave a CoP of 3.2 (based on Feb 2014 data only); the experimental system has consistently given an average winter CoP of 3.4. BTW, the actual CoPs include DHW from the heat pump at 50C.

The advantage of volunteering for the trial was that we got a free monitoring system installed and I still get the data sent weekly even though the trial finished in 2015.


Title: Re: One year in... some GSHP numbers
Post by: ringi on December 19, 2016, 11:24:29 AM
@Mikel,

What control system do you have?


Title: Re: One year in... some GSHP numbers
Post by: ringi on December 19, 2016, 11:27:13 AM
Heat pumps often cost a lot more then gas heating to run, it all comes down to the building and how people live in the building.   There was an experiment some time ago with a social landlord fitting heat pump, but the tenant demanded they were removed, as the tenants could not understand that a thermostat was not a on/off switch…..

The building also needs to be well enough insulated and draft proofed that it makes sense to keep the building heated while people are out at work etc.   Otherwise the heat pump has to operate at a high flow temperature so at to reheat the building quickly.


Title: Re: One year in... some GSHP numbers
Post by: Mikel on December 19, 2016, 01:18:48 PM
@ringi,

I do not have much detail for you. The company that installed the system put in an electricity meter and heat meter on the heat pump and an additional electricity meter on the house supply. There are a number of sensors around the house measuring various room temperatures and some modification to the heat pump itself. All the data collected is fed back to the company via our router.

I can provide program the temperature and schedule via a wireless control panel. I can also login to see the record of internal and external temperatures and the number and duration of heat pump usage.

The heat pump modifications were done with full knowledge and support of the manufacturer and I have a guarantee that the warranty would not be invalidated.

The control software is proprietary, so no details.

You make a very valid point that heat pumps are best at maintaining a consistent temperature rather than rapidly heating up as you would with gas or oil boilers.

If you are interested, I can post some example charts for days this month.


Title: Re: One year in... some GSHP numbers
Post by: dhaslam on December 19, 2016, 03:46:39 PM
Where  heat pumps go wrong  is when they are used  for  jobs they are not equipped to do.   In Northern Ireland there was a group of houses  fitted with ASHPs  that were set to heat  DHW first  but the problem was that in cold weather  they were running constantly trying  to get the water up to  temperature and didn't heat the houses properly.  It  seems that this is a fairly common. 

http://forum.buildhub.org.uk/ipb/topic/507-another-cheap-12kw-kingspan-aeromax-ashp/

A typical ASHP can  produce  4 to 5  kW  with an input of  1 kW in  7/35  conditions  and  about 50% more input when colder  so   if running for 12 hours the most it should cost on average is about  1.25 X 12 X  15p  = £2.25 per day.   However you have to add the cost of bringing DHW from  35C up to 55C  which would take about 2.5 kW of  heat per 100 litres.   


Title: Re: One year in... some GSHP numbers
Post by: DonL on December 19, 2016, 05:49:39 PM
Mikel Very interesting about your control system - it's particularly good that you have monitoring equipment to measure the real COP. I would love to know what my system really achieves but without heat measuring equipment I can only guess. Having said that I'm entirely content with the controls I have since I changed the bog standard thermostat for an accurate and programmable one. I drop the setpoint a degree or two over night and the ASHP generally stays off unless weather conditions are extreme. The setpoint is raised again at 6:00 am and the heat pump runs continuously part of the day to get back up to setpoint and then the temperature sits on setpoint until the woodburner lifts the temperature in the evening and the heat pump switches off. Finally, by having a heat pump with inverter drive, it is relatively good at matching heat demand without multiple start/stops and when it does start it is "soft start".

dhaslam I think heat pumps, like any other technology, have to be well designed and operated. Installers may not be very familiar with the technology and the house owners may expect to do things that the system is not designed for. Unfortunately there are quite a lot of bad experiences around which, in my view, is a pity as it may put people off a good solution. A new housing estate just down the road is being built with ASHP's and I look forward to seeing the results. First signs are promising as they are chosing between premium brand heat pumps and the rating looks sensible for a well insulated new build.


Title: Re: One year in... some GSHP numbers
Post by: ringi on December 19, 2016, 06:14:58 PM
Shame that A2A heat pumps are not allowed under RHI, as they give the quick response that lots of people want from a heating system.


Title: Re: One year in... some GSHP numbers
Post by: rogeriko on December 19, 2016, 08:53:46 PM
[A typical ASHP can  produce  4 to 5  kW  with an input of  1 kW in  7/35  conditions  and  about 50% more input when colder  so   if running for 12 hours the most it should cost on average is about  1.25 X 12 X  15p  = £2.25 per day.   However you have to add the cost of bringing DHW from  35C up to 55C  which would take about 2.5 kW of  heat per 100 litres.   
[/quote]



When it gets cold outside ie 0-2 degrees or your ground loop has cooled to 3-4 degrees, despite what all the manufacturers claim, in the real world you get a cop of 2. If you are heating DHW with a return loop around the hot taps and 6 bedrooms with the thermostat on 22 your electric bill will be more than anyone here can imagine.


Title: Re: One year in... some GSHP numbers
Post by: davec on December 22, 2016, 06:50:04 PM
The RHI for heat pumps is only available where mains gas is unavailable.

I remember this being a rule once upon a time but not sure this is still the case. Could you give a reference please?


Title: Re: One year in... some GSHP numbers
Post by: BruceB on December 23, 2016, 07:45:15 AM
I do not believe it was ever a rule.  My recollection is that it was in a consultation, but never implemented.

Certainly now, whether you have gas available or not does not feature in the questions asked when registering domestic or non-domestic rhi. I have installed HPs in gas areas, and rhi is claimed.


Title: Re: One year in... some GSHP numbers
Post by: titan on February 09, 2017, 08:59:37 PM
I do not believe it was ever a rule.  My recollection is that it was in a consultation, but never implemented.


Thread is a bit old now, just noticed it !. It was certainly part of my application processes no mains gas was a criteria although that was four years ago and the various schemes seemed to be forever changing. I was a self build that may have been a factor. I had given up on claiming RHI and did the install anyway only to find I actually qualified  for the then latest scheme as my commissioning date was three days after the start of the latest scheme, for once the bureaucracy worked in my favour.


Title: Re: One year in... some GSHP numbers
Post by: titan on February 09, 2017, 09:04:39 PM
Figures for 2016  2084 kWh that is 240 m2 heated area and dhw. Heating is on 24/7 30 weeks a year not needed for DHW the other weeks as it is provided by solar.

That is Kensa 8 kW GSHP


Title: Re: One year in... some GSHP numbers
Post by: davec on December 23, 2017, 11:18:08 AM
And, five years in....

Year1, Dec-2012/3 was:-
Quote
Total import 8361kWh (3412 high-rate, 4949 low). GSHP heating accounts for about 50% of this (4420); DHW about 10% (Immersion 650 plus heat-pump 216); the remaining 40% is cooking, light, appliances, kettle....

Year2, Dec-2013/4 was:-
Quote
Total import 7845kWh (3226 high-rate, 4619 low). GSHP heating accounts for about 50% of this (3725); DHW about 10% (Immersion 636 plus heat-pump 144); the remaining 40% is cooking, light, appliances, kettle....

Year3 Dec-2014/5 was:-
Quote
Total import 7862kWh (3324 high-rate, 4538 low). GSHP heating accounts for about 50% of this (4221); DHW about 6% (Immersion 343 plus heat-pump 128); the remainder is cooking, light, appliances, kettle, MineCraft....

Year4 Dec-2015/6 was:-
Quote
Total import 8841kWh (3871 high-rate, 4970 low). GSHP accounts for about 50% (4504); DHW about 7% (Immersion 563 + heat-pump 97); remainder much as before.... So, Y4 numbers up on Y3 but not massively out of kilter given that the kids are staying up longer nowadays, leaving lights on and doors open...

Year5 Dec-2016/7 was:-
Total import 8678kWh (3824 high-rate, 4854 low). GSHP accounts for about 50% (4633); DHW about 8% (Immersion 512 + heat-pump 170); remainder much as before.... So, Y5 numbers fairly flat with Y4; slightly more DHW could be because of constantly showering daughter...

DaveC.


Title: Re: One year in... some GSHP numbers
Post by: JohnS on December 23, 2017, 02:47:07 PM
Have you tried comparing your heating energy usage with heating degree day numbers?

http://www.degreedays.net/

Without knowing heating demand, it is impossible to know if you are improving or regressing.

At one stage I contributed weekly gas and electricity consumption data to Oxford University's climate project and they introduced me to degree days.  I used the data to verify that insulation projects and better control systems produced savings.  However, I also found that there were lots of noise in the data.  Eg home with in-laws for Christmas (extra heating) or away for Christmas and then kids off to university - small reduction in demand as their bedroom heating was turned off but reduced free heat from body warmth etc.  And then my retirement meaning I am at home more and therefore heating on more during the day plus feeling the cold more as I age etc.


Title: Re: One year in... some GSHP numbers
Post by: titan on December 23, 2017, 04:47:53 PM
 I did my initial energy demand projections for our new build  using degree days but and it is a big but it depends on how the nearest weather station  data correlates to your location. Now we live onsite I regularly check the local weather station with my own figures and the weather station (Just 5km away) is consistently 2-3 deg C min temp lower than  we get. Fortunately using their historical figures made the error in the right direction. Degree days are fine but  not foolproof.


Title: Re: One year in... some GSHP numbers
Post by: davec on December 23, 2017, 07:19:11 PM
Quote
I did my initial energy demand projections for our new build  using degree days but and it is a big but it depends on how the nearest weather station  data correlates to your location. Now we live onsite I regularly check the local weather station with my own figures and the weather station (Just 5km away) is consistently 2-3 deg C min temp lower than  we get. Fortunately using their historical figures made the error in the right direction. Degree days are fine but  not foolproof.

Aye, thank you, didn't know about degree days; every day is a school day!

I had a look at that website and the nearest 'real' weather station is Edinburgh Airport, only 20miles away but unfortunately at 120m lower elevation, which possibly makes a difference to the threshold temperature? However, I guess from their figures I'll get an indication of any variation from year to year to help interpret any trends in my own data (I'm getting a bit lazy nowadays... used to take readings every few weeks, now 3 months or so).

What I'm seeing in my numbers is that they're pretty consistent over 5 years, whole house demand about 9,000 KWh, about half of which is heating; and that there's no obvious 'creep' that might be a sign of something deteriorating: GSHP, borehole, external insulation, etc.

DaveC.


Title: Re: One year in... some GSHP numbers
Post by: gnarly on December 24, 2017, 09:02:33 AM
Thanks for all the data davec/titan.  What % of the time do these gshp systems run on the very coldest days?  (And do you feel warm enough? - appreciate it is a bit subjective and depends how you have the thermostat set).  I’m asking because I wonder if, in general, the heat pumps themselves are a bit oversized for 24hr operation on the coldest days and in fact you could get away with something smaller. (As long as you have the right approach with leaving it on continuously and not trying to heat up house from cold when you are in it!)


Title: Re: One year in... some GSHP numbers
Post by: marshman on December 24, 2017, 10:04:47 AM
My GSHP has just completed it's second year since install.  1st year consumption was 2330kWh. 2nd year much better at 1599kWh.  10kW Thermia heatpump, UFH, 300 ltr DHW tank.  Heat pump gets the DHW hot enough (55 deg) on its own with no help from immersion heater. I do have a solar diverter which does the hot water in the "summer" months -but is next to useless at this time of year. System runs 24/7. House is old  detached farmhouse (circa 1700's mainly)  but has been substantially renovated with UFH. It is 240 sq m

Much of the improvement has come from triple glazing and installing MHRV so I could stop all the unwanted draughts. We are in an exposed windy spot close to the English Channel.

Ground loop temps seem to be similar to last year at the moment but we shall see as the season progresses.

Gnarly, on the coldest days, recently had a couple of days where temp was -4 deg C over night and 0 deg C in the day (I know it's not as cold as up t'north, but cold enough for us southern softies), the heat pump was running for around 20 mins every hour. I suspect I could get away with a smaller pump but it is nice to have the "grunt" to heat the DHW when everyone is home having showers (4 grown up kids and their partners!).

Roger


Title: Re: One year in... some GSHP numbers
Post by: davec on December 24, 2017, 10:24:24 AM
Thanks for all the data davec/titan.  What % of the time do these gshp systems run on the very coldest days?  (And do you feel warm enough? - appreciate it is a bit subjective and depends how you have the thermostat set).  I’m asking because I wonder if, in general, the heat pumps themselves are a bit oversized for 24hr operation on the coldest days and in fact you could get away with something smaller. (As long as you have the right approach with leaving it on continuously and not trying to heat up house from cold when you are in it!)

The longest I've seen the GHSP compressor run is about 7 hours out of 24 when we had several weeks of sub-zero outside. There's a 100litre buffer tank to reduce cycling and it's interesting to note that the circulation pump operated about 17/24 at that time. Downstairs we have ufh and  it feels v. comfortable at 17degC, with 18 in the living room and 20 in the bathroom; upstairs is mostly heated by convection; we just have standard rads at ufh temperature.

But, the way I see it, the rating of the heat source is all about responsiveness... e.g. your normal gas boiler might be rated about 60,000 btu, way more than the running requirement, just so you can bring your rooms up to heat in a short timescale. Heat pumps that are left on all the time, are only required to replace insulation losses so can be rated less. Ours can deliver 9Kw while drawing 2Kw of electricity, which is obviously plenty for our usual needs (I think the next unit down would _just_ have provided for the building design with no contingency, e.g. wind-chill) but would likely take a couple of days to bring the whole structure up to temperature from cold... we just leave the whole system running all the time, supervised by a stack of timing and thermostat settings that churned a lot at first but haven't changed in over three years.

DaveC


Title: Re: One year in... some GSHP numbers
Post by: gnarly on December 24, 2017, 12:11:49 PM
Thanks... that’s very interesting, that’s about 33% duty cycle for both of you.  Of course you do want some headroom to accommodate warming house up from cold, or being able to turn off the heat pump for the evening peak if we ever get demand pricing...


Title: Re: One year in... some GSHP numbers
Post by: titan on December 24, 2017, 02:03:51 PM
Thanks for all the data davec/titan.  What % of the time do these gshp systems run on the very coldest days?  (And do you feel warm enough? - appreciate it is a bit subjective and depends how you have the thermostat set).  I’m asking because I wonder if, in general, the heat pumps themselves are a bit oversized for 24hr operation on the coldest days and in fact you could get away with something smaller. (As long as you have the right approach with leaving it on continuously and not trying to heat up house from cold when you are in it!)

The gshp should be sized for the maximum heating load certainly not oversized. The coldest here so far (2013)  was -12 C for almost a week  and that week it used 130 kWh which at 2.5kW load is around 6.8 hours  per 24 hours  but that was exceptional, last week with a couple of -6 C nights  it  used 60kWh for the week. The  house is always a constant temperature. I don't have the DHW 305 ltr cylinder as part of the normally on system just heat it as required which works fine, the tank is never cold and is up to 55 C in around 20 min, I think it saves unnecessary heating and standing losses but others will probably disagree or have different lifestyles.


Title: Re: One year in... some GSHP numbers
Post by: davec on December 26, 2017, 09:31:56 AM
Quote
... being able to turn off the heat pump for the evening peak if we ever get demand pricing...

We never turn the actual HP off but its internal controller does offer 'raise' and 'lower' timers for the compensation curve that we've set so the thing 'prefers' to run in the E10 low-rate times; there's also a standard CH programmer that runs the demand pumps to match occupancy and lifestyle. The rest is left to the exterior temp sensor plus thermal inertia.

DaveC.


Title: Re: One year in... some GSHP numbers
Post by: linesrg on December 26, 2017, 11:57:11 AM
Good Morning All,

As I've noted elsewhere the heat pump here operates 24/7 and modulates the output dependent on return temperature and the external air temperature.

This holiday period is the first time the four family members have been in the house and us all dependent on the heat pump for domestic hot water (the electric shower having been removed in summer). SWMBO wasn't terribly happy with their not being enough hot water for her bath at the end of the evening on Xmas Eve.

Yesterday evening saw us needing water for the two boys and myself having a shower, SWMBO having a bath and needing water for washing up those things that didn't go in the dishwasher. As the process was started sufficiently early in the evening the system coped (just). It did involve selecting the highest hot water temperature i.e. 58 degrees C to make it work and thus the heat pump/ immersion heater functions were operating every 30 minutes (for 30 minutes at a time) to achieve this.

This is the same situation if we are in the flat in Aberdeen to a degree except there of course the boiler can be 'forced' to focus on heating the hot water only rather than the operator being limited to only 30 minute bursts of water heating.

Regards

Richard


Title: Re: One year in... some GSHP numbers
Post by: marshman on December 12, 2018, 07:51:15 PM
Year 3 numbers!

GSHP now been up and running for 3 full years.

Year 1:  2330kWh
Year 2:  1599kWh
Year 3:  1468kWh

Figures are for Heating and DHW. Heating roughly from end of October through to end of April.  DHW in the "summer" is via PV diverter. If there is not enough sun then Heatpump is called into action to heat the water (not needed this year until end of October).

Year 3 lowest yet even after the "beast from the east". My wife has now retired so we are both home all day everyday, but she is quite happy (at the moment!).  Still working on insulation and draught proofing (mainly to stop the colder north easterly winds penetrating). Year 4 is off to a promising start - already 25% lower consumption than last year and it was turned on a week earlier.

Ground loops currently sitting around 11 deg C.  Last year they never went below 8 deg C.


Details: House:c1700's farmhouse, detached 240 sq m, exposed position. 10kW Thermia GSHP with 4 x 300m ground loops [50% of which are in shingle] driving UFH throughout. DHW - conventional vented system with 300 ltr storage tank.  System runs 24/7 regulated only by external temp sensor. House has MHRV system (needs it as it is now getting quite airtight!). Log Burner in the lounge (external air feed).

Roger


Title: Re: One year in... some GSHP numbers
Post by: gnarly on December 13, 2018, 08:02:50 AM
That's really interesting, thank you for posting.

Working back from a guessed COP of 4.3 say - which would make the electricity draw about 10kW/4.3 => 2.3kW
So 1468kWh / 2.3kW => 638 "full load equivalent" hours, which doesn't seem that much. (GSHP's can be designed for around 2000 FLEQ hours per year)

Do you think you could have got away with a much smaller pump and smaller ground array?  Even 5kW would have been on for only 1276 hours!  Given that you have an additional heatsource the power could be even lower as it doesn't need to cover the total load.

Makes me wonder if more people could install smaller heat pumps (using them in conjunction with some existing heat source like your log burner). 


Title: Re: One year in... some GSHP numbers
Post by: marshman on December 13, 2018, 09:38:16 AM
Yes we could have got away with a smaller pump BUT we wanted the RHI payment so the calculations said we needed a 10kW to cope with demand (our EPC stated over 30kWh p.a. for heating and 3kWh for hot water!).  Having said that it is nice to have a unit that can produce huge quantities of DHW when everyone is at home having showers etc.

The ground loops were a tricky issue. We are right on the edge of a shingle bank and no one knew how the loops would perform in shingle. So the installer was insistent on going over the top on loop length to make sure it would be OK and we didn't have any space issues. In the event the pipes ran out into an area of nice blue clay which sit below the water table most of the year, so they are very good. Also because he could get a large trenching machine in the extra cost was minimal. )Took 1 1/2 days to lay 1200m of pipework.  In a way I am pleased that we have such large loops as it keeps the temperature up throughout the season. In the middle of the "beast from the east" last year (late in the heating season) the incoming water temp was 8 deg C and it was -6 deg C out side. If we hadn't seen the news we would have been unaware that it was cold out! I assume the net result is that the heatpump is always running at a fairly high COP. In those conditions an ASHP efficiency would drop off, just when you need it the most.

The RHI will pay for the system in around 4 years. Even without the RHI I would still have installed something similar. As others have said it is so cheap to run (about £225 p.a. in electric for heat and DHW) and beats having to chop up wood and light the fire every day which we did for many years, in fact I wish we had done it years ago.

Roger

p.s. just checked on the heatpump and in 3 years it has run for 2029 hours for heating = 676 hours per year, so you "guess" seems correct.


Title: Re: One year in... some GSHP numbers
Post by: davec on December 23, 2018, 08:08:47 PM
And, six years in....

Year1, Dec-2012/3 was:-
Quote
Total import 8361kWh (3412 high-rate, 4949 low). GSHP heating accounts for about 50% of this (4420); DHW about 10% (Immersion 650 plus heat-pump 216); the remaining 40% is cooking, light, appliances, kettle....

Year2, Dec-2013/4 was:-
Quote
Total import 7845kWh (3226 high-rate, 4619 low). GSHP heating accounts for about 50% of this (3725); DHW about 10% (Immersion 636 plus heat-pump 144); the remaining 40% is cooking, light, appliances, kettle....

Year3 Dec-2014/5 was:-
Quote
Total import 7862kWh (3324 high-rate, 4538 low). GSHP heating accounts for about 50% of this (4221); DHW about 6% (Immersion 343 plus heat-pump 128); the remainder is cooking, light, appliances, kettle, MineCraft....

Year4 Dec-2015/6 was:-
Quote
Total import 8841kWh (3871 high-rate, 4970 low). GSHP accounts for about 50% (4504); DHW about 7% (Immersion 563 + heat-pump 97); remainder much as before.... So, Y4 numbers up on Y3 but not massively out of kilter given that the kids are staying up longer nowadays, leaving lights on and doors open...

Quote
Year5 Dec-2016/7 was:-
Total import 8678kWh (3824 high-rate, 4854 low). GSHP accounts for about 50% (4633); DHW about 8% (Immersion 512 + heat-pump 170); remainder much as before.... So, Y5 numbers fairly flat with Y4; slightly more DHW could be because of constantly showering daughter...

Year6 Dec-2017/ was:-
Total import 7792kWh (3259 high-rate, 4533 low). GSHP accounts for about 55% (4280); DHW about 5% (Immersion 71 + heat-pump 286); remainder much as before.... So, a bit more in line with Y2/3 so maybe Y4/5 was a relatively 'cauld-yin'. Different DHW numbers: I changed the program so the heat pump does more of the lift from what the solar thermal gives us and the immersion just gives an occasional kick over 60degC to ward off the L-word. Numbers seem to indicate COP > 1, even when heat pump is boosting to 55degC.

DaveC.