ᐅ Indoor heat pump in the basement not possible due to groundwater?
Created on: 10 Jan 2023 19:40
B
Baskervile
Hello,
I am currently planning the construction of a detached single-family house. When signing the contract, the general contractor promised an indoor heat pump in the basement, which is also specified in the contract. After receiving the soil survey report, which states a design groundwater level of -1.75m (-5.7 feet), I was told that an indoor heat pump is not possible because the air ducts cannot be sealed according to the relevant standards (DIN).
Is this really impossible or just too risky?
Furthermore, I received an offer for an outdoor installation along with a discount of just under €1000. During the planning discussions, I was told there would be an additional cost of about €5000 for the indoor heat pump. Overall, this feels a bit strange to me.
I would appreciate your experiences and any information on this topic.
A second question about civil engineering work: My general contractor insists on having the excavation supervised by an unexploded ordnance clearance service due to a note in the soil report, without any prior survey. He claims this is now a regulation by the BG-Bau (German Social Accident Insurance for the construction industry). Is this correct?
I am happy to provide further information or pictures if helpful. I hope I have posted this in the appropriate subforum.
Thank you very much for your responses!
I am currently planning the construction of a detached single-family house. When signing the contract, the general contractor promised an indoor heat pump in the basement, which is also specified in the contract. After receiving the soil survey report, which states a design groundwater level of -1.75m (-5.7 feet), I was told that an indoor heat pump is not possible because the air ducts cannot be sealed according to the relevant standards (DIN).
Is this really impossible or just too risky?
Furthermore, I received an offer for an outdoor installation along with a discount of just under €1000. During the planning discussions, I was told there would be an additional cost of about €5000 for the indoor heat pump. Overall, this feels a bit strange to me.
I would appreciate your experiences and any information on this topic.
A second question about civil engineering work: My general contractor insists on having the excavation supervised by an unexploded ordnance clearance service due to a note in the soil report, without any prior survey. He claims this is now a regulation by the BG-Bau (German Social Accident Insurance for the construction industry). Is this correct?
I am happy to provide further information or pictures if helpful. I hope I have posted this in the appropriate subforum.
Thank you very much for your responses!
A
Allthewayup11 Jan 2023 13:22I find the suggestions from previous contributors regarding unexploded ordnance to be good and would also aim for a compromise with the general contractor. However, as mentioned before, this requires you to be actively involved to limit the risk to an acceptable level.
Concerning the design water level, I can imagine that during the exploratory drilling very clayey soil was encountered, which causes surface water to remain for a long time, or there is perched groundwater. The groundwater table alone does not define the design water level. Values such as the hundred-year peak water level/precipitation, etc., are also considered. Then an additional 30cm (12 inches) risk allowance is added to reach the design water level. At least, this is how it is described in our soil report. Whether there is a standardized calculation formula is beyond my knowledge.
We have groundwater at -2.5m (-8 feet 2 inches), with fluctuations of about only 50cm (20 inches), but the design water level was set at 0, meaning ground surface level, in the report. That roughly corresponds to the water level during the worst Danube flood in 1999, the most severe in the last 100 years.
The objection from parcus is justified, but there are many factors that can lead to this type of assumption being chosen. It is worth checking if there are alternative options and whether the general contractor can (technically) accommodate them.
Was your house design available to the geologist at the time the soil report was created? The excerpts you quoted from the report seem very general and less specific to your project.
Concerning the design water level, I can imagine that during the exploratory drilling very clayey soil was encountered, which causes surface water to remain for a long time, or there is perched groundwater. The groundwater table alone does not define the design water level. Values such as the hundred-year peak water level/precipitation, etc., are also considered. Then an additional 30cm (12 inches) risk allowance is added to reach the design water level. At least, this is how it is described in our soil report. Whether there is a standardized calculation formula is beyond my knowledge.
We have groundwater at -2.5m (-8 feet 2 inches), with fluctuations of about only 50cm (20 inches), but the design water level was set at 0, meaning ground surface level, in the report. That roughly corresponds to the water level during the worst Danube flood in 1999, the most severe in the last 100 years.
The objection from parcus is justified, but there are many factors that can lead to this type of assumption being chosen. It is worth checking if there are alternative options and whether the general contractor can (technically) accommodate them.
Was your house design available to the geologist at the time the soil report was created? The excerpts you quoted from the report seem very general and less specific to your project.
@face26
Here are some facts:
With R290, modern heat pumps can now achieve supply temperatures of up to 75°C (167°F) and still operate at ambient temperatures between -15 and -20°C (5 and -4°F), so electric backup heaters are no longer necessary. The GWP is 3.
Indoor, or better yet, split heat pumps have an advantage for cooling loads by using R32 as the refrigerant, which has a GWP of 675.
(R410A performs very poorly in comparison, with a GWP of 2088.)
However, policymakers have also recognized this and already implemented it in the BEG 2023.
Then try telling the intake air it’s not allowed to come from around the corner. These facts can clearly be measured through air flow and temperature. 🙂
Therefore, you can forget about oscillating fans, for example — these devices simply stabilize at an average temperature.
Here are some facts:
With R290, modern heat pumps can now achieve supply temperatures of up to 75°C (167°F) and still operate at ambient temperatures between -15 and -20°C (5 and -4°F), so electric backup heaters are no longer necessary. The GWP is 3.
Indoor, or better yet, split heat pumps have an advantage for cooling loads by using R32 as the refrigerant, which has a GWP of 675.
(R410A performs very poorly in comparison, with a GWP of 2088.)
However, policymakers have also recognized this and already implemented it in the BEG 2023.
Then try telling the intake air it’s not allowed to come from around the corner. These facts can clearly be measured through air flow and temperature. 🙂
Therefore, you can forget about oscillating fans, for example — these devices simply stabilize at an average temperature.
To be honest, I don’t really know what to say about that. Weren’t you the one who already mixed up some terms in another thread?
Monovalent has nothing to do with monoblock, and indoor installation does not mean split unit.
On the topic of airflow, how far apart are the intake and discharge points on an outdoor air-to-water heat pump?
Monovalent has nothing to do with monoblock, and indoor installation does not mean split unit.
On the topic of airflow, how far apart are the intake and discharge points on an outdoor air-to-water heat pump?
@face26
The terms are clearly defined.
Monoblock = Cold and hot side combined in one unit
Monovalent = Only one heat generator
These heat pumps can be operated with R290.
Split = At least two heat generators
These cannot be operated with R290.
Otherwise, you can also refer to the Duden dictionary for the meaning of "mono" as single, sole, or individual.
The terms are clearly defined.
Monoblock = Cold and hot side combined in one unit
Monovalent = Only one heat generator
These heat pumps can be operated with R290.
Split = At least two heat generators
These cannot be operated with R290.
Otherwise, you can also refer to the Duden dictionary for the meaning of "mono" as single, sole, or individual.
parcus schrieb:
The indoor or rather split heat pump shows its advantage... If that is so clear, then please explain this to me?
and this:
parcus schrieb:
The outdoor heat pump is much more efficient because of the monovalent operation. What does being installed outdoors have to do with monovalent operation?
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