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
23 Nov 2015 18:45
That will only become clear in the long term. So far, the maintenance costs have been zero. I will soon have the sacrificial anode in the domestic hot water tank checked, but otherwise, nothing. I also don’t service my refrigerators; the readings and pressures are all correct.
D
djon25
23 Nov 2015 20:43
Maybe someone who has been using a heat pump for a few years can share their experience.
N
Nordmann
23 Nov 2015 21:11
Hi, the systems are actually almost maintenance-free. For my two (rental) heat pumps, the technician only had to come in case of malfunctions.....not because of maintenance backlog, in case someone is thinking that.
L
Legurit
28 Nov 2015 10:18
For the commissioning of the heating system: it has been running since Wednesday exclusively on electricity in screed heating mode and has already consumed 580 kWh of electricity.

Never design your heating system incorrectly, or rather endure the cold in winter before the electric heating element has to be used.
L
larina
28 Nov 2015 11:27
@BeHaElJa
Which pump do you have? I haven’t checked the details closely yet ops:

After a lot of consideration and reading, we have decided on a ground source heat pump with trench collectors (+ solar system). The builder works in the construction industry and can do a lot of the work himself (including using his own excavator, so no rental costs), which significantly reduces the expenses.
We are interested in the Stiebel Eltron WPF 07. Has anyone had any experience with it?
L
Legurit
28 Nov 2015 11:33
We have a Vaillant Flexocompact with 5.3 kW. We would have liked to install a trench collector as well, but couldn’t find anyone with experience in that, so now it will be a deep borehole (expensive).