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!
@face26
No one is taking away your opinion; it's only if you refuse to follow the facts—which even politicians acknowledge—that you are creating distractions.
Just take a look at your thermal insulation verification according to DIN 18599 (possibly the older DIN 4701) or the HVAC calculation for heating load according to DIN[B] 12831 for your split heat pumps; the facts are all there. Your heat pumps were designed based solely on these.
----
Please note that many manufacturers refer to DIN 15450 for positioning.
DIN EN 15450 sets criteria for the design of heating systems in buildings that operate exclusively with electric heat pumps or heat pumps combined with other heat generators. It also addresses power supply, positioning, noise emissions, heat input, and sizing. However, the standard explicitly does not cover the overall planning of these systems. It applies only to the heat pump itself, the interfaces to the heat distribution and heat transfer system (for example, buffer tanks), and the control of the entire system. Systems primarily designed for cooling, and those operating simultaneously in cooling and heating mode, are not covered by the standard.
Regarding indoor installation and duct routing, there are numerous court rulings on heat pump retrofits due to inefficiency.
Therefore, it may be advisable to obtain confirmation that no flow short-circuit can occur, a test that even a layperson can perform using a small fog machine.[/B]
No one is taking away your opinion; it's only if you refuse to follow the facts—which even politicians acknowledge—that you are creating distractions.
Just take a look at your thermal insulation verification according to DIN 18599 (possibly the older DIN 4701) or the HVAC calculation for heating load according to DIN[B] 12831 for your split heat pumps; the facts are all there. Your heat pumps were designed based solely on these.
----
Please note that many manufacturers refer to DIN 15450 for positioning.
DIN EN 15450 sets criteria for the design of heating systems in buildings that operate exclusively with electric heat pumps or heat pumps combined with other heat generators. It also addresses power supply, positioning, noise emissions, heat input, and sizing. However, the standard explicitly does not cover the overall planning of these systems. It applies only to the heat pump itself, the interfaces to the heat distribution and heat transfer system (for example, buffer tanks), and the control of the entire system. Systems primarily designed for cooling, and those operating simultaneously in cooling and heating mode, are not covered by the standard.
Regarding indoor installation and duct routing, there are numerous court rulings on heat pump retrofits due to inefficiency.
Therefore, it may be advisable to obtain confirmation that no flow short-circuit can occur, a test that even a layperson can perform using a small fog machine.[/B]
B
Baskervile13 Jan 2023 21:01Allthewayup schrieb:
Okay, I can partially understand the reasons in favor of an indoor installation.
Have you made any progress with the manufacturer regarding the wall penetration issue with pressurized water?
What is your general contractor’s (GC’s) take on this conflict of interest?
If there really is no approved method for waterproofing and your GC refuses, that has to be accepted for now. The groundwater level is quite high. What will it be like in the next 80 years? Weather events tend to become more intense. I would also play it safe here.
On our 300 sqm (3,230 sq ft) plot, there is also an outdoor unit placed in a less than ideal location, but that was the ‘lesser evil’ for us.
Let us know if there are any new developments! Maybe you’ll get helpful advice if you share a bird’s eye view of your basement floor plan and the plot? We got some great tips that we hadn’t thought of ourselves. I haven’t had a new appointment with the GC since then. In the last discussions, the indoor heat pump was clearly rejected if I insisted on it, without any guarantees. However, a friend who is an architect sees no problem with an indoor installation, as long as it is done “properly,” but the GC does not want to hear that.
This is the situation. For me, the only reasonable place for the outdoor heat pump is next to the garage driveway, although that is also quite far away.
I am now arranging an expert for construction supervision to see what they have to say about the topic...
A
Allthewayup14 Jan 2023 13:01I have taken a look at the floor plan. @OWLer is absolutely right about the stairs leading to the basement. You can also find discussions online about how vulnerable basement stairs are when it comes to waterproofing.
Next are the two light wells with a parapet height of 1.02 m (3 ft 4 in) – I am also very critical of this. Among other things, waterproof windows (resistant to groundwater pressure) would need to be installed here (if such windows even exist or are permitted in this size). By now, I don’t understand your general contractor either, when he says he doesn’t guarantee the air vents but has no problems with the basement stairs and the light wells.
We also have a light well, and precisely because of the risk of groundwater, we set the parapet height to 1.45 m (4 ft 9 in) or even higher – especially since there were no approved waterproof windows in the required size.
Although we used waterproof concrete construction, we still have leaks in the basement. I strongly recommend involving a specialist planner or expert to develop a waterproofing concept for your basement. I regret not doing this myself! It is also absolutely advisable to have an external supervisor monitor the basement construction. We didn’t do this either (we convinced ourselves that construction engineers and architects among our friends would check it if needed, but it never worked out timewise).
A waterproofing concept must consider all possible influencing factors and conditions in advance. It is commendable that you have already had a soil survey performed; that is the essential foundation for the following concept.
After seeing your floor plan, the air vent is your smallest problem here, and I speak from my own very recent and painful experience.
*EDIT:
Could you explain exactly how the basement will be constructed? Formwork or precast panels? Thickness? What kind of concrete is planned? How will the joint between the base slab and the wall be waterproofed? Pentaflex membranes or injection hoses?
Do you possibly have an excerpt from your building description? I’m repeating myself when I say that many other issues need to be clarified rather than blindly trusting the general contractor – really, believe me...
Next are the two light wells with a parapet height of 1.02 m (3 ft 4 in) – I am also very critical of this. Among other things, waterproof windows (resistant to groundwater pressure) would need to be installed here (if such windows even exist or are permitted in this size). By now, I don’t understand your general contractor either, when he says he doesn’t guarantee the air vents but has no problems with the basement stairs and the light wells.
We also have a light well, and precisely because of the risk of groundwater, we set the parapet height to 1.45 m (4 ft 9 in) or even higher – especially since there were no approved waterproof windows in the required size.
Although we used waterproof concrete construction, we still have leaks in the basement. I strongly recommend involving a specialist planner or expert to develop a waterproofing concept for your basement. I regret not doing this myself! It is also absolutely advisable to have an external supervisor monitor the basement construction. We didn’t do this either (we convinced ourselves that construction engineers and architects among our friends would check it if needed, but it never worked out timewise).
A waterproofing concept must consider all possible influencing factors and conditions in advance. It is commendable that you have already had a soil survey performed; that is the essential foundation for the following concept.
After seeing your floor plan, the air vent is your smallest problem here, and I speak from my own very recent and painful experience.
*EDIT:
Could you explain exactly how the basement will be constructed? Formwork or precast panels? Thickness? What kind of concrete is planned? How will the joint between the base slab and the wall be waterproofed? Pentaflex membranes or injection hoses?
Do you possibly have an excerpt from your building description? I’m repeating myself when I say that many other issues need to be clarified rather than blindly trusting the general contractor – really, believe me...
B
Baskervile14 Jan 2023 14:12Don’t worry, the general contractor had plenty of concerns about the windows and the staircase as well. However, all of these issues were resolved. The windows will be installed as waterproof basement windows, though not in the size shown on the original plan (I don’t have the revised plan yet). There will also be a waterproof roof over the basement stairs.
I don’t have the construction description on hand at the moment. I only know that formwork will be used. Details about the type of concrete, etc., have not been provided to me. However, I assume everything will be appropriate. In this region, all basements must be waterproof against ground water pressure, and the contractor is a local supplier. From previous projects, I am not aware of any problems related to this.
The only issue we have yet to resolve is the heat pump.
I don’t have the construction description on hand at the moment. I only know that formwork will be used. Details about the type of concrete, etc., have not been provided to me. However, I assume everything will be appropriate. In this region, all basements must be waterproof against ground water pressure, and the contractor is a local supplier. From previous projects, I am not aware of any problems related to this.
The only issue we have yet to resolve is the heat pump.
Similar topics