Ground Source Heat Pumps

lovesgshp

PKChang wrote: »

Thanks Geotherm; as best as I can tell, past about 7 meters deep this temp is year-round. The house in just below 2000 ft up in the mountains, and the soil in pretty rocky/clay based. I was considering running a 1" down and two 3/4" returns in order to make the most of the hole, but my experience is all theoretical, and I know the efficiency of the hole's exchange could be reduced by a three pipe run. We're trying to cut out heating expenses, so I will be looking at a single panel DHW solar system for the summer requirements, which are WAY down from the winter needs. I had expected that a 12Kw HP would be about right for us.....

Just checked the details on a recent quote we completed for a 9Kw output unit with existing borehole 30 cm wide. Probe diameter is 40mm x 4. The other cost factor is the sealing grout which is expensive. Difference in cost to a horizontal setup was Euro 10000.00 for this client.
I would consider getting a couple of quotes in for both options if you have the available land.
Hope this helps

lovesgshp

poohbear59 wrote: »

I have been in to have a look at the K2 info.

Results are:
heat pump operating no. of hours-1891 h
distribution-255DWH, 75% RAD
Add heat in operation 25h

I checked the elec meter and we have used 6464 units since we put the pump in. We have an electric oven and grill, washing machine and fridge freezer, all A rated and a tumble dryer possibly C rated and use low energy bulbs throughout.

Without a torch yesterday I thought it was 7000 units used so although it is high it is closer to my estimated usage.

I hope you can make sense of this data and advise me on how to use the data properly in future. Thank you.

The running hours seem high, as does the Add Heat. Can you give me the % for that from menu 7.4.
Distribution is usually 20%/80% for the pump.
Have you a buffer tank as well?

poohbear59

Geotherm wrote: »

The running hours seem high, as does the Add Heat. Can you give me the % for that from menu 7.4.
Distribution is usually 20%/80% for the pump.
Have you a buffer tank as well?

The running hours is since it went in last March.

The guests have arrived now so I will have to wait until Friday when they leave to have a look. We live 1300 feet above sea level which is lower than you. Our building is a 17th century stone barn conversion with no loft but it is super insulated, way above building regs with double glazing throughout.

If we were living in the house ourselves I am sure we would have a much better idea of useage and would supplement it more with the wood burner. I have had the occasional customer saying it wasn't warm enough: the heating has been on all year, but at the same time they have had windows fully open. We have to expect higher electricity usage when it is a completely new energy source than if it was lived in constantly.

We are both delighted with the savings compared to the oil bills we could have had and the lesser impact on the environment than oil.

lovesgshp

No problem Poohbear59.

We normally use circa 10000Kwh per year for everything here. My running hours, based on a similar time scale as yours were 1627 for the pump. Additional heat total 26 hrs over 6 years.
What temp have you for the hot water and heating?
Currently, we are snowed in, with lunchtime outside temp -1.8C!! Pump has been operating about 15hrs day over the last week, as we have been down to -12C overnight with wind chill factor!!!

poohbear59

geotherm, I love the picture. We are often like that too but the snow here is thawing and is a dirty colour at the edges of the roads.

I had a look at the heat pump on change over day. We have now used 27h additional heat! The option 7.4 wasn't available on my display. I have asked our heating engineer who fitted the system to come and have a look at it for me. Hopefully he will call in tonight after work.

paceinternet

Geotherm, what temperatures (in and out of the pump) is your source water running at in these conditions?
Bore hole or slinky?
And how much does this change through the year?

IVT/European standard EN255 quote performance at 0/35 and 0/50
Range looks to be -5 to +20
Does performance go off much when source is -5 ?

Do you have any knowledge of installations struggling with slinky installations in prolonged low ambient temperatures?

Many thanks

Should say I am asking partly because of reading this:
http://www.icax.co.uk/Ground_Source_Heat_Pumps.html

lovesgshp

paceinternet wrote: »

Geotherm, what temperatures (in and out of the pump) is your source water running at in these conditions?
Bore hole or slinky?
And how much does this change through the year?

IVT/European standard EN255 quote performance at 0/35 and 0/50
Range looks to be -5 to +20
Does performance go off much when source is -5 ?

Do you have any knowledge of installations struggling with slinky installations in prolonged low ambient temperatures?

Many thanks

Should say I am asking partly because of reading this:
http://www.icax.co.uk/Ground_Source_Heat_Pumps.html

Inlet temp from ground loop is 3.5C, out -1.8c. This is a standard ground loop system (not slinky) @ 1.5 mtrs depth and 2 excavations x75 mtrs x 1.2 mtrs wide, minimum excavation distance between each trench is 3mtrs. 2 lines in and 2 out in each @ 30cm spacing, giving 300 mtrs of inlet flow.
Ground temp does change through the year, but if you consider -10 outside to 3.5 coming in then the heat delta is 13.5C. We are set here on 18.5C internal temp, with room sensor influence on level 7, so normally just under 19C which is recommended for UFH systems.
I have not reached a -5 source yet here, believe the lowest was 0C, with no degradation in performance, but longer operating times. This is mainly due to the low insulation level in the house here.
Currently, the UHF temps are below 30C, so the pump is operating well within design range.

Hope this helps

paceinternet

So did you design on 50 w/m for the ground loop to get 15 kw, or something less in the 30-50 w/m range?

lovesgshp

paceinternet wrote: »

So did you design on 50 w/m for the ground loop to get 15 kw, or something less in the 30-50 w/m range?

The design was based on the thermal analysis of the house after restoration. I have not got the data on file here, but will see if I can still get it from our office records.

lovesgshp

poohbear59 wrote: »

geotherm, I love the picture. We are often like that too but the snow here is thawing and is a dirty colour at the edges of the roads.

I had a look at the heat pump on change over day. We have now used 27h additional heat! The option 7.4 wasn't available on my display. I have asked our heating engineer who fitted the system to come and have a look at it for me. Hopefully he will call in tonight after work.

27hr is far too much since your last message at 25 hrs, unless you have the additional heat operating every day. What is the DHW temperature set at?