ᐅ Experiences with Ground Source Heat Pumps

Created on: 23 Oct 2015 21:40
S
Saruss
Hello,
here I would like to share some experiences and data regarding my brine heat pump and deep drilling, based in part on the expert’s "questionnaire":

a) What is the soil composition on your property?
Up to 3m (10 feet) silty, fine sandy, clayey soil
Up to 4m (13 feet) slope debris, rock fragments
Then bedrock (mainly limestone)

b) How deep was the drilling?
Drilled twice to a depth of 72m (236 feet)

c) How much did the drilling cost?
€10,400 including double U-probes DN25
Grouting material with 2.0 W/mK thermal conductivity
Permitting process (building permit / planning permission)
Pressure-tight house entry at the basement and underground routing of supply lines (about 25m (82 feet))
Filling/draining equipment, filling, pressure testing, etc. (all inclusive)

d) How much did the system cost?
System: Tecalor TTc 05 with heating output at B0/W35 of 5.8 kW and coefficient of performance (COP) of 4.8
Cost: €9,800

e) Were there any difficulties during installation, if so, what kind?
Because the water used to flush out the drilled material during drilling seeped away, a "small compressor" was needed to blow it out with air. However, it had to be placed on a neighbor’s property who had not yet started building. The machine was the size and approximate weight of a 20-ton truck but was off-road capable. This caused a 2-day delay because the compressor first had to be transported to our site. No additional costs were charged.

f) How is the daily operation?
"Like a refrigerator." Once the parameters on the heating system are correctly set, the only thing that should be done is occasionally reading the information/data such as operating hours and source temperature. Otherwise, it runs "on its own," just like any heating system. When the door is closed, the unit is virtually inaudible. Very discreet since, apart from the cabinet in the utility room, nothing else is visible (all brine pipes are underground).

e) What are the operating costs for which living area?
Currently, a living area of 180sqm (1937 sqft) is heated, plus an additional 65sqm (700 sqft) of cellar space within the insulated thermal envelope (these rooms are around 15-16°C (59-61°F) on the coldest days). From September 2014 to September 2015, 2,000 kWh of electricity was consumed for heating and hot water (2 adults, 1 baby, 1 toddler). The house is a KfW-70 standard building according to the 2009 energy saving regulations, which already met the required technical standards before the central ventilation system with enthalpy heat exchanger was installed (we decided to add this after the initial applications).

f) to be continued ....

Note regarding the comparison of the coefficient of performance (COP):
Since optimizing the heating curve and settings at the end of last year, the system has had a COP of about 5.5. Operating hours are around 1200; the deep borehole was drilled approximately 20% deeper than initially recommended by the companies, at our own request.
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annab377
5 Aug 2020 20:35
I have decided on the ground source heat pump. I am fascinated by the technology that uses the relatively warm earth almost all year round to supply heating or, in the summer, the cool ground for passive cooling.

Although it is probably slightly more expensive on average than an air-to-water heat pump, I don’t have an unnecessary outdoor unit.
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Ybias78
5 Aug 2020 20:41
annab377 schrieb:

I decided on a ground-source heat pump. I find the technology fascinating because it uses the relatively warm ground almost all year round to provide heating or, in summer, the cool earth for passive cooling.

Even though it is probably on average slightly more expensive than an air-to-water heat pump. But I don’t have an unnecessary outdoor unit.

The question is how well does it cool? It’s not really designed for that. The argument about the outdoor unit is valid. Do you save on additional costs compared to an air-to-water heat pump?
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annab377
5 Aug 2020 21:41
A ground-source heat pump generally has a higher COP (Coefficient of Performance, also known as the annual performance factor) compared to an air-source heat pump because the heat source does not drop to very low subzero temperatures during winter.

As for how effective the passive cooling function of the ground-source heat pump is, that was actually my question. Well, it certainly can’t be compared to an air conditioning system, which removes warm air and also positively affects humidity levels for human comfort. However, if you can keep a solid structure cooler by using a 20°C (68°F) cooled screed compared to without passive cooling, I believe that does make a difference in preventing the building from overheating during hot summer periods.
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User0815
5 Aug 2020 22:23
Have you already checked if you are allowed to use a ground source heat pump? In some areas, geothermal energy is not permitted.
Tolentino5 Aug 2020 22:58
Regularly located in water protection areas.
For example, in my case. Although supposedly a special permit may be possible.
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Ybias78
6 Aug 2020 06:11
User0815 schrieb:

Have you already checked if you are allowed to use a ground source heat pump? In some areas, geothermal systems are not permitted.

No problem here. If anything, I would prefer one with deep drilling rather than ground loops.