ᐅ Indoor heat pump in the basement not possible due to groundwater?
Created on: 10 Jan 2023 19:40
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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!
parcus schrieb:
Split = at least two heat generators
However, these cannot be operated with R290. I'm only reading this now. Unfortunately, you're mistaken. "Split" means the refrigeration circuit is divided.
A split heat pump can also be operated monovalently in terms of heating. In other words, only the heat pump produces hot water and heats.
Just so you know, I have an air-to-water heat pump installed inside my basement. It's a monobloc.
My neighbor has a split system. It is also operated monovalently.
@[B]face26
R32 has a boiling point of -52°C (-62°F), while R290’s boiling point is -41°C (-42°F).
That is why in refrigeration technology R744 (–57°C (-70°F)) is also used. Both R290 and R744 are natural refrigerants that qualify for the BEG incentive.
What is your reason for wanting to install an indoor unit outdoors and not operate it as a monovalent system?
The main idea is usually to save costs and to use better technology.
---
Always referring to new builds as in the EP, so no hybrid solutions like in NWG or existing buildings.
R32 has a boiling point of -52°C (-62°F), while R290’s boiling point is -41°C (-42°F).
That is why in refrigeration technology R744 (–57°C (-70°F)) is also used. Both R290 and R744 are natural refrigerants that qualify for the BEG incentive.
What is your reason for wanting to install an indoor unit outdoors and not operate it as a monovalent system?
The main idea is usually to save costs and to use better technology.
---
Always referring to new builds as in the EP, so no hybrid solutions like in NWG or existing buildings.
@face26
That’s why your neighbor still can’t operate the split heat pump in monovalent mode.
The terms exclude each other. MONO = ONE heat generator, not split or multi-split = at least two. (Splitting simply means dividing)
It doesn’t matter where the monoblock is located; if it is indoors, it is not an outdoor monoblock but an indoor monoblock.
The term monoblock is not technically significant and only describes a configuration where everything is housed within a single unit.
That’s why your neighbor still can’t operate the split heat pump in monovalent mode.
The terms exclude each other. MONO = ONE heat generator, not split or multi-split = at least two. (Splitting simply means dividing)
It doesn’t matter where the monoblock is located; if it is indoors, it is not an outdoor monoblock but an indoor monoblock.
The term monoblock is not technically significant and only describes a configuration where everything is housed within a single unit.
No idea what you’re trying to explain to me with this refrigerant confusion.
A split system doesn’t have two heat generators. It’s called a split system because the components are divided into two units, not because there are two heat generators.
Monoblock is the opposite of split.
Monovalent is the opposite of bivalent.
One term refers to a “construction type,” the other to how it is operated. But honestly, I don’t even know why I’m starting this again.
A split system doesn’t have two heat generators. It’s called a split system because the components are divided into two units, not because there are two heat generators.
Monoblock is the opposite of split.
Monovalent is the opposite of bivalent.
One term refers to a “construction type,” the other to how it is operated. But honestly, I don’t even know why I’m starting this again.
B
Baskervile13 Jan 2023 00:15Thank you for the numerous responses.
According to a phone consultation, Novelan itself sees no issues with an indoor installation.
The reasons for preferring an indoor installation are:
- Sensitivity to noise. Even though the units are very quiet nowadays, I do not want it placed directly under the bedroom window, which would be the shortest distance. Elsewhere on the property would require very long pipes.
- Aesthetics.
- Space conditions on the property.
- Longevity of the unit if it is not exposed to weather.
Here is the excerpt regarding groundwater conditions:
“Groundwater and/or percolating water were detected in all boreholes. The highest water level was recorded after completion of drilling at borehole BS1 at 3.40 m (11 feet) below ground level (reference level -3.62 m). The groundwater levels found represent low water levels due to prolonged dryness. ... At the groundwater measurement point, groundwater rises up to about 1.5 m (5 feet) below ground level (~365.25 m above sea level) have been recorded over the past 10 years.
...
The design water level can only be estimated and is set at a reference level of -1.75 m (-6 feet), taking into account a natural groundwater fluctuation range of ±1.75 m (±6 feet). The building components in contact with the ground are classified, according to DIN 18533-1, as exposure class W2-E (pressurized water) and must be sealed accordingly.”
According to a phone consultation, Novelan itself sees no issues with an indoor installation.
The reasons for preferring an indoor installation are:
- Sensitivity to noise. Even though the units are very quiet nowadays, I do not want it placed directly under the bedroom window, which would be the shortest distance. Elsewhere on the property would require very long pipes.
- Aesthetics.
- Space conditions on the property.
- Longevity of the unit if it is not exposed to weather.
Here is the excerpt regarding groundwater conditions:
“Groundwater and/or percolating water were detected in all boreholes. The highest water level was recorded after completion of drilling at borehole BS1 at 3.40 m (11 feet) below ground level (reference level -3.62 m). The groundwater levels found represent low water levels due to prolonged dryness. ... At the groundwater measurement point, groundwater rises up to about 1.5 m (5 feet) below ground level (~365.25 m above sea level) have been recorded over the past 10 years.
...
The design water level can only be estimated and is set at a reference level of -1.75 m (-6 feet), taking into account a natural groundwater fluctuation range of ±1.75 m (±6 feet). The building components in contact with the ground are classified, according to DIN 18533-1, as exposure class W2-E (pressurized water) and must be sealed accordingly.”
Regarding the groundwater topic, I can’t contribute much. Our unit is also installed indoors in the basement, with intake and exhaust air routed through light wells. Unfortunately, I can’t provide details on how exactly the groundwater issue was handled, but we had to build with a waterproof concrete shell ("white tank"). I’m also not sure what was done with the light wells—whether they were sealed again—could be, but I simply don’t remember.
On the subject of indoor installation:
We had the same concern about not finding a suitable spot. Our neighbors, who have the "same" plot, have their unit placed basically next to the terrace. I find that dreadful. At the location where the light wells are now, three properties meet and three houses stand close together; back when we planned this almost four years ago, we considered that too risky in terms of noise development. Today, I might reconsider.
Indoor installation definitely has disadvantages.
Any efficiency loss, if it exists at all, I would dismiss. It’s more important to ensure the rest of the setup fits (design, sizing, components, e.g., without buffer tank, pipe spacing, etc.). That influences efficiency much more than whether the unit is indoors or outdoors.
Disadvantages have already been partially mentioned: you need very careful planning and execution. Wall openings must fit properly and be correctly insulated.
A crucial element is noise decoupling. The indoor unit must sit on a properly decoupled base. Pipes should also be flexible, otherwise structure-borne noise transfers to the building.
It’s definitely recommended to equip the technical room with a soundproof door. (Please also consider this in ventilation planning if relevant, because with a soundproof door, airflow balancing via undercuts or transfer openings might not work.)
Actually, based on current knowledge, I would reconsider indoor versus outdoor installation. However, mainly because the choice of heat pump units is much broader now and outdoor units have become noticeably quieter.
If the unit ever needs to be replaced—hopefully far in the future—there’s still the option to go with an outdoor unit then. Sure, it requires more effort because the wall openings need to be closed again, but it’s not as if the entire house would have to be remodeled.
On the subject of indoor installation:
We had the same concern about not finding a suitable spot. Our neighbors, who have the "same" plot, have their unit placed basically next to the terrace. I find that dreadful. At the location where the light wells are now, three properties meet and three houses stand close together; back when we planned this almost four years ago, we considered that too risky in terms of noise development. Today, I might reconsider.
Indoor installation definitely has disadvantages.
Any efficiency loss, if it exists at all, I would dismiss. It’s more important to ensure the rest of the setup fits (design, sizing, components, e.g., without buffer tank, pipe spacing, etc.). That influences efficiency much more than whether the unit is indoors or outdoors.
Disadvantages have already been partially mentioned: you need very careful planning and execution. Wall openings must fit properly and be correctly insulated.
A crucial element is noise decoupling. The indoor unit must sit on a properly decoupled base. Pipes should also be flexible, otherwise structure-borne noise transfers to the building.
It’s definitely recommended to equip the technical room with a soundproof door. (Please also consider this in ventilation planning if relevant, because with a soundproof door, airflow balancing via undercuts or transfer openings might not work.)
Actually, based on current knowledge, I would reconsider indoor versus outdoor installation. However, mainly because the choice of heat pump units is much broader now and outdoor units have become noticeably quieter.
If the unit ever needs to be replaced—hopefully far in the future—there’s still the option to go with an outdoor unit then. Sure, it requires more effort because the wall openings need to be closed again, but it’s not as if the entire house would have to be remodeled.
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