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.
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.
Tego12 schrieb:
I agree with bookstar...
The best protection against legionella is a properly sized tank, where under normal operation the entire water volume is fully used and replaced every 1 to a maximum of 2 days. Alternatively, simply use a hygienic storage tank or a fresh water station.
The fear about this is definitely justified 100%.
Regards, Nika
guckuck2 schrieb:
The total output of the probe is about 80% of the capacity of the selected heat pump.Does this mean that if I calculate a heating load of 10 kW (for simplicity) for a single-family house according to DIN 12831, then I only need a deep borehole with a cooling/heating capacity of 8 kW? I would still choose a 10 kW heat pump?
For the horizontal collector, however, a larger collector won’t hurt, or does it also need to be precisely matched to the heating load of the house, and can too much capacity be detrimental?
I’m a bit conflicted because I’ve seen answers here saying that a modulating brine heat pump is not worth the extra cost compared to an on/off heat pump. What is currently the general opinion in the forum in 2020? I have already spoken to several geothermal companies, and they all recommended a modulating heat pump.
annab377 schrieb:
Does this mean that if, according to DIN 12831, I calculate a heating load of 10 kW for a single-family house (for easier calculation), then I only need a deep borehole with a cooling/heating capacity of 8 kW? Would the heat pump still be rated at 10 kW?
With the horizontal ground heat exchanger, however, a larger collector can't really hurt, or does it also need to be precisely matched to the heating load of the house, and can too large actually be a disadvantage?
I'm a bit torn because there are answers here saying that a modulating brine-to-water heat pump isn't worth the extra cost compared to an on/off heat pump. What is the current forum opinion in 2020? I have already spoken to several geothermal companies, and they always mentioned a modulating heat pump. For the horizontal ground heat exchanger, oversizing it doesn't cause harm, but the benefits of doing so are limited. Most people who oversize the collector do so out of pure caution. You can trust the trench sizing tool in the purple forum — it already includes safety margins, and in practice even smaller trenches are sufficient without problems (there are plenty of real-life examples in the forum).
Whether modulating or not seems to be a matter of personal belief. The newer technology offers advantages, especially when combined with rooftop photovoltaics, results in less frequent cycling and therefore theoretically longer service life, and is more efficient. However, it is significantly more expensive and more complex technically (so there is also a risk of component failure). Nowadays, I would choose a modulating heat pump, although 3.5 years ago I opted for a fixed-capacity model.
annab377 schrieb:
Does this mean that if I calculate a heating load of 10 kW according to DIN 12831 for a single-family house (for easier calculation), then I only need a deep borehole with a cooling/heating capacity of 8 kW? I would still choose a heat pump rated at 10 kW?
With a slinky ground collector, however, a larger collector probably wouldn’t hurt, or does it also need to be precisely matched to the heating load of the house and could too much actually be a disadvantage?
I’m a bit torn because there are also responses here saying that a modulating brine-to-water heat pump is not worth the extra cost compared to an on/off heat pump. What is the current forum opinion in 2020? I already spoke with several geothermal companies and they all recommended a modulating heat pump.I can only speak from my personal experience regarding modulation—I have a heat pump without modulation. Based on my observations over the past years, I wouldn’t know what advantages modulation would bring. Due to the very large thermal mass (the screed), the heat pump cycles are very limited with the appropriate settings, meaning I have only rarely observed more than 4-5 cycles per day (depending on hot water usage; if the whole family showers or bathes one after another, it obviously needs to be balanced out). Since the building is otherwise quite well insulated and built with solid construction, the indoor temperature still fluctuates less than 0.5°C (0.9°F), which is definitely not noticeable for us.
If a heat pump operating with modulation, i.e., at partial load, does not have a worse efficiency compared to full load, then I would not see why modulation would be harmful. I also don’t believe there is a noticeable difference in the average brine temperature. This remains relatively stable for me both during heating phases and overall.
Regarding the above post: I don’t see an advantage to combining photovoltaics with a modulating heat pump. The input power of the heat pump is relatively low compared to the photovoltaic system. When it is cold in winter—especially at night—there is no sun anyway, and if the sun is shining during the day in winter, it usually provides enough power to operate the heat pump (mine needs maybe about 1.5 kW even in the final phase of heating hot water, thanks to high coefficients of performance). Otherwise, I use the photovoltaic system in the current season to boost the hot water temperature somewhat around midday; that usually lasts until the next noon, and even on cloudy days, the photovoltaic typically delivers about 1.5 kW.
annab377 schrieb:
Does this mean that if, according to DIN 12831, I calculate a heating load of 10 kW for a single-family house (for easier calculation), then I only need a geothermal borehole heat exchanger with a cooling/heating capacity of 8 kW? I would still use a heat pump rated at 10 kW?Correct.
Plus the client’s (or the drilling company’s) safety margin.
Saruss schrieb:
I can only speak from my personal experience regarding modulation – I have a heat pump without modulation. Based on my observations over recent years, I don’t see what advantages modulation would bring. Due to the large heat storage capacity (the screed), cycling of the heat pump is very limited with appropriate settings; I have rarely observed more than 4-5 cycles per day.I also have a brine-to-water heat pump without modulation and similar experience. About 4-5 cycles per day in winter, typically 2 cycles without heating operation in summer (domestic hot water, 180 L (48 US gallons) integrated storage). This results in roughly 1250 cycles per year. Compared to the compressor’s durability of about 100,000 starts, the expected compressor lifetime would be around 80 years.
Therefore, wear and tear is—in my opinion—not an argument for a modulating brine-to-water heat pump. That’s why I didn’t choose such a model, which would have cost four figures more. I opted for a very simple brine-to-water heat pump.
Thanks for your responses. And yes, depending on the additional cost for the inverter compressor, it might actually be worth considering a brine-to-water heat pump without modulation.
Since you mentioned a 180 L (48 gallons) integrated storage tank @guckuck2 (how many people?), what are the pros and cons of a hot water storage tank integrated directly into the heat pump? It’s clear that it should not be chosen too large. I once read that a maximum of 270 liters (71 gallons) is recommended for 4 people.
Since you mentioned a 180 L (48 gallons) integrated storage tank @guckuck2 (how many people?), what are the pros and cons of a hot water storage tank integrated directly into the heat pump? It’s clear that it should not be chosen too large. I once read that a maximum of 270 liters (71 gallons) is recommended for 4 people.
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