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.
A
AleXSR70019 May 2020 21:15When referring to the 45°C (113°F) water temperature mentioned here, are we talking about domestic hot water for showering, etc.? Due to concerns about Legionella bacteria, shouldn’t the temperature now be set to 60°C (140°F) or higher and factored in accordingly?
I wanted to ask how much more cost-effective a heat pump really is compared to a gas heating system. In my previous rental, a geothermal heating system was installed with the claim that costs could be reduced by up to 60%. The reality was that costs increased by 100-200%. When the Legionella discussion came up and the temperature was raised from 45°C (113°F) to 65°C (149°F), costs went up again. There was no photovoltaic system, so electricity was supplied entirely from the grid. Are heat pumps similarly problematic in this regard? If so, do you generally save money only if a photovoltaic system is present, or does it end up costing about the same as gas?
I wanted to ask how much more cost-effective a heat pump really is compared to a gas heating system. In my previous rental, a geothermal heating system was installed with the claim that costs could be reduced by up to 60%. The reality was that costs increased by 100-200%. When the Legionella discussion came up and the temperature was raised from 45°C (113°F) to 65°C (149°F), costs went up again. There was no photovoltaic system, so electricity was supplied entirely from the grid. Are heat pumps similarly problematic in this regard? If so, do you generally save money only if a photovoltaic system is present, or does it end up costing about the same as gas?
S
Strahleman19 May 2020 22:15Yes, 45°C (113°F) for domestic hot water, such as for showering, is sufficient. Using a heat pump to reach the 60°C (140°F) you mentioned is very inefficient. With proper drinking water hygiene and especially a complete water replacement every 2-3 days, using domestic hot water at 45°C (113°F) is not a problem.
You usually need electric backup heating via the immersion heater, which increases electricity costs (this explains the additional costs you’ve experienced so far). It’s mainly a matter of correctly sizing your heating system. With a heat pump, you need to plan the heating surfaces and domestic hot water heating more carefully, considering pipe spacing, flow temperature, etc.
As for whether geothermal energy is generally cost-effective compared to a gas boiler, I honestly don’t know. A gas boiler is considerably cheaper to purchase, at least without government subsidies like BAFA grants. Whether gas prices will rise significantly in the coming decades is also uncertain. Ultimately, it comes down to your personal preference. For myself and my family, I would aim to heat as much as possible without relying on fossil fuels.
You usually need electric backup heating via the immersion heater, which increases electricity costs (this explains the additional costs you’ve experienced so far). It’s mainly a matter of correctly sizing your heating system. With a heat pump, you need to plan the heating surfaces and domestic hot water heating more carefully, considering pipe spacing, flow temperature, etc.
As for whether geothermal energy is generally cost-effective compared to a gas boiler, I honestly don’t know. A gas boiler is considerably cheaper to purchase, at least without government subsidies like BAFA grants. Whether gas prices will rise significantly in the coming decades is also uncertain. Ultimately, it comes down to your personal preference. For myself and my family, I would aim to heat as much as possible without relying on fossil fuels.
A
AleXSR70020 May 2020 05:21Strahleman schrieb:
Yes, 45°C (113°F) for domestic hot water like for showering. With a heat pump, it is very inefficient to go up to the 60°C (140°F) you mentioned. With proper drinking water hygiene and especially a regular complete water replacement every 2-3 days, there is no problem using domestic hot water at 45°C (113°F).
Usually, electric heating rods need to be used as supplementary heating, which drives up electricity costs (hence your additional expenses based on your previous experience). It is basically a design issue of your heating system. With a heat pump, you have to plan a bit more carefully for the heating surface design and also for domestic hot water heating, including pipe spacing, flow temperature, and so on.
Whether geothermal energy is cost-effective compared to a gas boiler? Honestly, I don’t know. A gas boiler is definitely cheaper to install, at least without any government subsidies. Also, it’s hard to say if gas prices will increase that much in the next decades. It also depends on your personal preferences. For me and my family, I would aim to heat as much as possible without fossil fuels. Fossil fuels are naturally undesirable, but at the same time, electric heating powered by coal-fired power plants is not any better. And if the costs double or even triple, then the question is whether it might be better to postpone remodeling for 20 years. Technically, that could be advantageous, and you might potentially save that money.
All of this, of course, only if geothermal really is as unprofitable as it has been.
Regarding the water temperature, I have to say that the statement is confusing.
You have no influence on "water hygiene." You don’t "contaminate" your water yourself. And outside the building, you have just as little control over the pipes as over the quality of the municipal water supply.
I’m also not sure how you are supposed to completely replace the water. Aside from possible waste, you can’t empty a hot water storage tank by showering or similar. Fresh water just flows in immediately. So, you don’t get a complete turnover but only dilution, which does nothing to stop legionella.
You could heat the water storage tank to 60-80°C (140-176°F) every 1-2 weeks to kill everything, but that also causes huge costs.
It all sounds like the heat pump is a modern but still unprofitable and economically risky solution, especially considering legionella. It would definitely be worthwhile if all the electricity for it came from photovoltaic panels combined with batteries. But if I’m not mistaken, such a self-sufficient system easily costs between 10,000 and 30,000 (k€). Plus, the cost of replacing the batteries every so many years or decades.
AleXSR700 schrieb:
Fossil fuels are obviously not desirable, but at the same time, electric heating powered by electricity from coal-fired power plants isn’t any better. And if the costs double or even triple, the question arises whether it might be better to delay remodeling by 20 years. Technically, that could be advantageous, and you potentially save the money.
Of course, this only applies if geothermal energy really turned out to be as uneconomical as claimed.
Regarding the water temperature, I have to say the statement is confusing. You have no influence on the “water hygiene.” You don’t “contaminate” your water. Outside the building, you have just as little control over the pipes as over the quality from the municipal water supplier. I’m also not sure how you would completely replace the water. Aside from the possible waste, you cannot empty a hot water storage tank by showering or similar means. Fresh water flows in immediately. So, you don’t get a complete exchange but only a dilution, which does nothing against Legionella bacteria. You could heat the water tank to 60-80°C (140-176°F) every one to two weeks to kill everything, but that would generate substantial costs.
It all sounds like heat pumps are a modern but still mostly uneconomical and, when operated economically, rather risky option (Legionella). It would certainly be worthwhile if you could power the entire system with photovoltaic energy combined with batteries. But if I’m not mistaken, such a self-sufficient system quickly costs 10,000-30,000 Euros. Plus the cost of replacing batteries every few years or decades.No, it can be very economical. The motto here is: it depends. You can save a lot of money by doing some of the installation work yourself. You definitely have to be careful with the design of the underfloor heating. And for those really worried about Legionella, a storage tank with a fresh water station can be installed. However, you cannot ignore the additional costs involved there.
S
Strahleman20 May 2020 07:51AleXSR700 schrieb:
Fossil fuels are obviously not desirable, but at the same time, electric heating powered by coal-fired power plants isn’t any better. That’s true, but thanks to the high annual performance factor of a geothermal heat pump—which can be achieved with smart system design—it requires very little electricity. This electricity can also be sourced from renewables, for example via your own photovoltaic system or the right electricity provider.
AleXSR700 schrieb:
Regarding water temperature, I have to say the statement is confusing.
You have no influence on the “water hygiene.” You don’t “contaminate” your water. And outside the building, you have as little control over the pipes as over the quality provided by the utility company. Drinking water hygiene isn’t just about visible dirt in the water. It also includes protection against Legionella bacteria. Legionella are always present in drinking water, but their growth is encouraged only within certain temperature ranges—between 25 and 50°C (77 and 122°F). If you fill your water storage tank at these temperatures, you should regularly perform a full water exchange. Therefore, the size of the water tank should always be chosen according to the number of people living in the house. This way, Legionella won’t generally be an issue. Alternatively, a fresh water station can help, but that typically costs about 1,000 euros more.
AleXSR700 schrieb:
You could heat the water tank to 60–80 °C every 1-2 weeks to kill everything, but even then, it causes huge costs. You should actually avoid this, because this short-term temperature increase (e.g., via Legionella control) tends to make Legionella more resistant to higher temperatures.
AleXSR700 schrieb:
It all sounds like the heat pump is a modern but still unprofitable and, when operated economically, rather risky undertaking (Legionella). No, you’ve only picked out the negative aspects. A heat pump that is incorrectly set up or designed is indeed less cost-effective. But Legionella are no problem with proper design. With a geothermal heat pump, you can generate 4 to 5 kWh of heat energy from 1 kWh of electricity if well designed. Operating costs for gas boilers and geothermal heat pumps are therefore quite similar. Thanks to government subsidies, the initial investment is now roughly on the same level as well. If you install a controlled mechanical ventilation system—which nowadays can often be subsidized together with a heat pump, especially if they are technically linked for joint control—then a heat pump becomes the more cost-effective option.
Additionally, a geothermal heat pump can provide passive cooling and allows you to feed electricity back into the grid if you install a photovoltaic system on your roof.
A
AleXSR70020 May 2020 08:50In this thread, temperatures of 45°C (113°F) have been mentioned several times, which are officially discouraged because, as you pointed out, Legionella bacteria can thrive under these conditions.
How can a thermal storage tank be completely drained? Normally, water is constantly flowing in. Preventing this would require opening an air inlet every few days to empty the tank.
However, this would mean that
a) every time you would have to reheat from just a few °C (around 40°F) in winter,
b) you would either have to discard warm water directly into the drain or someone would eventually have a cold shower.
To me, none of this sounds particularly economical or ecological.
I understand that the heating system may not require temperatures above 55°C (131°F), but what about the domestic hot water? I don’t yet see how this could be realistically achieved without the problems mentioned above.
I also increasingly see heat pumps installed in new apartment buildings, where, as far as I know, minimum temperatures are legally mandated and usually no photovoltaic systems are installed. This seems to me to be quite disadvantageous for the tenants.
How do you practically “drain” your thermal storage tank completely?
I do not want to criticize heat pumps, but I am trying to assess them realistically for my own situation. Without a sufficiently sized photovoltaic system, they seem rather uneconomical and possibly not truly environmentally friendly. Due to the current electricity grid, there is effectively no green electricity. The majority is still generated from non-renewable sources.
If environmental impact is the main concern, district heating using waste heat from power plants might actually be more interesting. Although I am not familiar with the specific efficiency figures and it may only be environmentally unfriendly for nuclear power plants.
How can a thermal storage tank be completely drained? Normally, water is constantly flowing in. Preventing this would require opening an air inlet every few days to empty the tank.
However, this would mean that
a) every time you would have to reheat from just a few °C (around 40°F) in winter,
b) you would either have to discard warm water directly into the drain or someone would eventually have a cold shower.
To me, none of this sounds particularly economical or ecological.
I understand that the heating system may not require temperatures above 55°C (131°F), but what about the domestic hot water? I don’t yet see how this could be realistically achieved without the problems mentioned above.
I also increasingly see heat pumps installed in new apartment buildings, where, as far as I know, minimum temperatures are legally mandated and usually no photovoltaic systems are installed. This seems to me to be quite disadvantageous for the tenants.
How do you practically “drain” your thermal storage tank completely?
I do not want to criticize heat pumps, but I am trying to assess them realistically for my own situation. Without a sufficiently sized photovoltaic system, they seem rather uneconomical and possibly not truly environmentally friendly. Due to the current electricity grid, there is effectively no green electricity. The majority is still generated from non-renewable sources.
If environmental impact is the main concern, district heating using waste heat from power plants might actually be more interesting. Although I am not familiar with the specific efficiency figures and it may only be environmentally unfriendly for nuclear power plants.
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