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.
S
Saruss
4 Nov 2016 20:42
My graphic was created with LibreOffice, where I quickly input my sensor data. As mentioned, my outdoor measurement is taken in the shade at about ground level, but quite close to the house wall – I believe official weather stations measure somewhat differently.
L
Legurit
4 Nov 2016 20:51
Possible – still good to get some reference values – I’m curious to see how our wood stove performs when it really gets cold.
S
Saruss
4 Nov 2016 21:06
Yes. According to the diagram above, your average was 1°C (1.8°F) colder, which would roughly mean about 15 kWh more per month for me. However – as I already mentioned – in the first year my consumption was actually significantly higher (even with the same settings and temperature-adjusted). From further measurements, I also know that my humidity was considerably higher in that first year.
L
Legurit
4 Nov 2016 21:46
Thank you for the information.
S
Saruss
16 Jan 2017 19:43
It is getting colder; consumption including hot water, heating, pump, etc. (entire system)
November 2016
208 kWh
Degree day total 449

December 2016
265 kWh
Degree day total 506 (approx. 3.7°C (38.7°F) average temperature throughout the month – outside at the basement window)
S
Saruss
7 Feb 2017 21:41
January 2017
358 kWh
Heating degree days total 622 (approximately 0°C (32°F) average temperature throughout the month – outside at the basement window)