ᐅ Two-family house KfW 70 with air-source heat pump heating and ventilation system
Created on: 25 Oct 2013 20:00
M
MadPat
Hello
This is about a new build: a two-family house. We are interested in the ground floor apartment (with garden). It has 100m² (1,076 sq ft), a concrete slab foundation, underfloor heating, is a KfW 70 house, and is heated with an air-source heat pump. Additionally, the apartment will have an automatic ventilation system for supply and exhaust air.
Now, my questions.
Is an air-source heat pump recommended for heating? Most of my acquaintances say no. They say it’s too expensive (electricity costs are rising dramatically) and that a gas heating system would be better. Also, there is a problem in summer with unnecessary costs for hot water production, and the pump runs even when not in use.
Second topic: automatic ventilation. It all sounds good (sales pitch): no need to ventilate manually, windows can usually stay closed, etc. BUT how long does the ventilation system work without faults? What happens if it breaks down? If something gets clogged or whatever? So far, no clear answers. In the end, would the house have to be opened up and everything repaired at great expense?
Who has experience and maybe actual numbers for me? I prefer real costs and figures, not the ones given during sales talks.
This is about a new build: a two-family house. We are interested in the ground floor apartment (with garden). It has 100m² (1,076 sq ft), a concrete slab foundation, underfloor heating, is a KfW 70 house, and is heated with an air-source heat pump. Additionally, the apartment will have an automatic ventilation system for supply and exhaust air.
Now, my questions.
Is an air-source heat pump recommended for heating? Most of my acquaintances say no. They say it’s too expensive (electricity costs are rising dramatically) and that a gas heating system would be better. Also, there is a problem in summer with unnecessary costs for hot water production, and the pump runs even when not in use.
Second topic: automatic ventilation. It all sounds good (sales pitch): no need to ventilate manually, windows can usually stay closed, etc. BUT how long does the ventilation system work without faults? What happens if it breaks down? If something gets clogged or whatever? So far, no clear answers. In the end, would the house have to be opened up and everything repaired at great expense?
Who has experience and maybe actual numbers for me? I prefer real costs and figures, not the ones given during sales talks.
Mycraft schrieb:
... Because very few systems are properly planned/dimensioned. Who is responsible for this? This issue is not limited to air-source heat pump systems but applies to all types of heat generators! "Hope" is neither legally enforceable, part of any contract, nor a reasonable basis for a significant investment decision!
Mycraft schrieb:
...In my opinion, an air-source heat pump is a very expensive heating option nowadays, because, as mentioned, it is mostly built following a fixed pattern... Neither the manufacturer nor the seller is responsible for this if the homeowner does not take personal responsibility themselves! How many air-source heat pump systems have you technically planned, dimensioned precisely, and supervised in practical operation?
Mycraft schrieb:
...A ground-source or groundwater heat pump is, of course, a completely different matter... Not at all! All heat generators initially have market approval. Whether they are actually suitable for the specific demand case is a completely different matter! Mycraft schrieb:
......because hardly anyone can adhere to the ventilation intervals... Which ones? Mycraft schrieb:
.....Now, moisture must be removed, and assuming one is employed—and I think people building a house generally are—then it is simply not possible to ventilate 3–4 times a day because they are not at home... Why is it necessary to ventilate 3–4 times? Who believes in this blanket sales claim? Mycraft schrieb:
....I have not regretted my decision and had a central controlled residential ventilation system installed as part of the build two years ago...everyone should be able to afford the extra 5–6 thousand EUR... That may be so, but economically it is quite questionable! How much "ventilation energy loss" can I permanently offset by spending 5–6 thousand EUR? Completely aside from interest, depreciation, inflation rate, and current operating costs like energy use and filter changes. The comfort of a controlled residential ventilation system is indisputable, but it is not absolutely necessary in every case and economically rather marginal!
I understand when someone defends their own decision with all means afterward.
However, a universally applicable "ultimate solution" cannot be derived from this!
Best regards.
MadPat schrieb:
Yes, but how is a layperson supposed to find out if everything is correctly sized? In sales talks, they always calculate and show you that everything is precisely planned and sized, but there is no guarantee. You are welcome to send me these calculations for a formal review. It takes me just a few minutes to spot serious, formal errors since I usually recognize the usual suspects quite quickly!
Aside from that, if someone provides a service and actually offers no guarantee or warranty, it is practically reckless to enter into a contractual agreement without careful examination!
Best regards
Yes, there is a guarantee. The entire building is covered for 10 years. However, whether the ground source heat pump provides ENOUGH power to properly heat the apartment during winter, or whether the internal ventilation is SUFFICIENT to maintain the climate and ensure good air circulation, is not addressed.
MadPat schrieb:
Yes, no, well, there is indeed a warranty. Ten years on the entire building. But whether the air-source heat pump actually provides ENOUGH capacity to properly heat the apartment in winter, or whether the internal ventilation is SUFFICIENT to maintain the climate and ensure good air circulation, that is not addressed. This can definitely lead to a costly mistake regarding operating costs, depending on the intended period of use. Moreover, it is not only the performance of the air-source heat pump under design conditions that matters, but over the entire evaluation period!
With a short usage period, financial consequences of a miscalculation tend to be temporary, unlike with long-term use!
Therefore, one should carefully assess everything before making a long-term contractual commitment!
Best regards.
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