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
If you don’t understand the importance of refrigerants (boiling point), you won’t realize that outdoor and indoor heat pumps are two different heat pump concepts. The term “split” usually means that the condenser is located indoors, and that a secondary heat source such as an electric heating element, wood, oil, or gas heating is required, because the split heat pump cannot reach high temperature ranges. This is what defines bivalent operation.
You also can’t simply swap refrigerants due to technical and physical differences (e.g., bivalence point, limit temperature) based on the heat pump design.
Typically, split heat pumps operate bivalently with a second heat source, often an integrated heating element that is also indirectly used for domestic hot water supply.
An exception is when a split heat pump is used in a hybrid setup with, for example, a tankless water heater and is sufficient for space heating. In that case, it is operated “monovalently,” just as the tankless water heater is operated monovalently. There are two separate heat sources in this scenario.
Note that the annual performance factor always includes all heat sources, including the heating element, whereas it is often observed that only the heat output for space heating is measured.
This also explains the difference in efficiency, since outdoor units are usually operated monovalently and do not require a second heat source.
Modern stratified storage tanks are important for all hydronic heat pumps, although unfortunately, there are only a handful of options available.
Test results can be found publicly at the Swiss SPF Institute for Solar Technology.
[B]---
Reference is always to residential buildings without cascades and no air-to-air heat pumps
If you don’t understand the importance of refrigerants (boiling point), you won’t realize that outdoor and indoor heat pumps are two different heat pump concepts. The term “split” usually means that the condenser is located indoors, and that a secondary heat source such as an electric heating element, wood, oil, or gas heating is required, because the split heat pump cannot reach high temperature ranges. This is what defines bivalent operation.
You also can’t simply swap refrigerants due to technical and physical differences (e.g., bivalence point, limit temperature) based on the heat pump design.
Typically, split heat pumps operate bivalently with a second heat source, often an integrated heating element that is also indirectly used for domestic hot water supply.
An exception is when a split heat pump is used in a hybrid setup with, for example, a tankless water heater and is sufficient for space heating. In that case, it is operated “monovalently,” just as the tankless water heater is operated monovalently. There are two separate heat sources in this scenario.
Note that the annual performance factor always includes all heat sources, including the heating element, whereas it is often observed that only the heat output for space heating is measured.
This also explains the difference in efficiency, since outdoor units are usually operated monovalently and do not require a second heat source.
Modern stratified storage tanks are important for all hydronic heat pumps, although unfortunately, there are only a handful of options available.
Test results can be found publicly at the Swiss SPF Institute for Solar Technology.
[B]---
Reference is always to residential buildings without cascades and no air-to-air heat pumps
parcus schrieb:
Outdoor heat pumps and indoor heat pumps represent two different heat pump concepts. The term “split” not only means that usually the condenser is located indoors,Yes
parcus schrieb:
but that an electric heater / wood, oil, or gas heating system is required as a second heat source, since the split heat pump cannot achieve very high temperature ranges.No
parcus schrieb:
An electric heater / wood, oil, or gas heating system is needed as a second heat source, (....) which also corresponds to a bivalent operation.Yes
Of course, split heat pumps can be designed and operated monovalently. However, depending on the climate (NAT) or the preference for a legionella prevention program, this is not always advisable.
@OWLer
Using a system as primary heat only is only possible if there is a hybrid setup, meaning an external second heat source is present (see DIN 18599).
What someone operates inefficiently or in a way that could be harmful to health is their own responsibility, as long as contaminants do not enter the public network.
In private residential construction, you will hardly find any split system operating as a single-source heating system,
because economic efficiency is also considered, especially since no one knows where electricity prices are headed.
This is particularly relevant due to the introduction of dynamic electricity tariffs. Time periods for electricity consumption are rarely freely selectable.
Ultimately, it is about the ratio of electricity consumption in kWh to the amount of heat produced in kWh.
Using a system as primary heat only is only possible if there is a hybrid setup, meaning an external second heat source is present (see DIN 18599).
What someone operates inefficiently or in a way that could be harmful to health is their own responsibility, as long as contaminants do not enter the public network.
In private residential construction, you will hardly find any split system operating as a single-source heating system,
because economic efficiency is also considered, especially since no one knows where electricity prices are headed.
This is particularly relevant due to the introduction of dynamic electricity tariffs. Time periods for electricity consumption are rarely freely selectable.
Ultimately, it is about the ratio of electricity consumption in kWh to the amount of heat produced in kWh.
A
Allthewayup13 Jan 2023 12:23Okay, I can partly understand the reasons in favor of installing the unit indoors.
Have you made any progress with the manufacturer regarding the question of wall penetrations in areas with hydrostatic water pressure?
What does your general contractor say about the conflict of interest?
If there really is no approved method for waterproofing and your general contractor refuses, you have to accept that for now. The groundwater level is quite high. What will it be like over the next 80 years? Weather events tend to become more extreme. I would also play it safe.
On our 300 m² (3,229 sq ft) plot, there is also an outdoor unit in a rather suboptimal 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 layout and property. We received great tips that we hadn’t thought of ourselves.
Have you made any progress with the manufacturer regarding the question of wall penetrations in areas with hydrostatic water pressure?
What does your general contractor say about the conflict of interest?
If there really is no approved method for waterproofing and your general contractor refuses, you have to accept that for now. The groundwater level is quite high. What will it be like over the next 80 years? Weather events tend to become more extreme. I would also play it safe.
On our 300 m² (3,229 sq ft) plot, there is also an outdoor unit in a rather suboptimal 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 layout and property. We received great tips that we hadn’t thought of ourselves.
@OWLer
As soon as germs enter the public sewer system, you could be held legally responsible.
See the regulations regarding toilets with bidet functions. Germs can now be traced back to individual apartments.
Aside from that, operating a split system like this is inefficient.
Germany has simply fallen behind in modern heat pump technology; our neighboring countries have been ahead for years,
even though their electricity costs are much lower.
However, the BEG funding program has now responded to this. Since only natural refrigerants will be permitted in the future, the topic of split heat pumps,
and thus indoor heat pumps in new buildings, will become a thing of the past.
As soon as germs enter the public sewer system, you could be held legally responsible.
See the regulations regarding toilets with bidet functions. Germs can now be traced back to individual apartments.
Aside from that, operating a split system like this is inefficient.
Germany has simply fallen behind in modern heat pump technology; our neighboring countries have been ahead for years,
even though their electricity costs are much lower.
However, the BEG funding program has now responded to this. Since only natural refrigerants will be permitted in the future, the topic of split heat pumps,
and thus indoor heat pumps in new buildings, will become a thing of the past.
Similar topics