ᐅ Two-family house KfW 70 with air-source heat pump heating and ventilation system
Created on: 25 Oct 2013 20:00
M
MadPatHello
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.
I
Irgendwoabaier25 Oct 2013 20:21Good evening,
I have quite a few questions, so there should be some answers as well.
Your text is very difficult to read, not only because many conventions regarding spacing and punctuation are ignored, but also because the use of capital letters in normal writing is completely missing.
For an economic evaluation of a selected heat generator, it is essential to know the realistically expected heating loads as well as the connection and installation costs. Additionally, there are numerous legal requirements. Therefore, a general statement like “gas is cheaper” or “heat pumps are useless” is not helpful.
There are many online contributions about ventilation systems. One should distinguish between strongly ideological and technically sound views, then decide based on the specific project. It is important to consider more than just the difference between a “central” or “decentralized” system. And how long the system works without malfunction cannot be predicted. There is only a certain probability that it will function properly for a given period. The necessary steps for maintenance, troubleshooting, and replacement again depend on the chosen system.
For my project, a ventilation system is simply necessary due to boundary conditions like “when and how long ventilation can be done” — the required ventilation intervals could not be maintained otherwise. For this reason, an air-to-water heat pump as the heat generator is not the most expensive solution.
Kind regards,
I.
I have quite a few questions, so there should be some answers as well.
Your text is very difficult to read, not only because many conventions regarding spacing and punctuation are ignored, but also because the use of capital letters in normal writing is completely missing.
For an economic evaluation of a selected heat generator, it is essential to know the realistically expected heating loads as well as the connection and installation costs. Additionally, there are numerous legal requirements. Therefore, a general statement like “gas is cheaper” or “heat pumps are useless” is not helpful.
There are many online contributions about ventilation systems. One should distinguish between strongly ideological and technically sound views, then decide based on the specific project. It is important to consider more than just the difference between a “central” or “decentralized” system. And how long the system works without malfunction cannot be predicted. There is only a certain probability that it will function properly for a given period. The necessary steps for maintenance, troubleshooting, and replacement again depend on the chosen system.
For my project, a ventilation system is simply necessary due to boundary conditions like “when and how long ventilation can be done” — the required ventilation intervals could not be maintained otherwise. For this reason, an air-to-water heat pump as the heat generator is not the most expensive solution.
Kind regards,
I.
Hello,
Best regards.
MadPat schrieb:If the conditions are right and the system is well planned and properly sized, then yes.
....air/water heat pump recommended as heating system...?
MadPat schrieb:Where do these acquaintances get their information for this general, incorrect conclusion?
....most of my acquaintances say no. Too expensive (electricity costs rise endlessly)...
MadPat schrieb:Apparently someone hasn’t read the user manual or didn’t understand the existing control system!
....and the pump keeps running even when not in use...
Best regards.
Now, the conclusion that an air source heat pump does not deliver the expected performance and you end up heating with electricity is partly correct. This is because very few systems are properly planned or sized.
At least that has been my experience over the past few years... with the many standard houses being built today, something is installed that roughly fits and can provide the heating capacity needed...(on paper) but in reality, the electric heating element runs at low temperatures, and of course, it consumes a significant amount of energy...
So, in my opinion, an air source heat pump is a very expensive heating option nowadays, because, as I said, most are installed following a standard template...
A geothermal or groundwater heat pump is, of course, a completely different matter.
Regarding ventilation:
A central ventilation system is practically essential in highly insulated and airtight houses today... anyone who still does not understand this cannot really be helped... since almost no one realistically maintains the recommended ventilation intervals, and if construction damage occurs, the builder is off the hook because it is often said that the "ventilation intervals were not followed."
However, moisture must be removed, and assuming you are employed (which I think most people are when building a house), you simply cannot ventilate 3-4 times a day because you are not home...
I do not regret my decision to have a central controlled ventilation system installed during the construction two years ago... the additional cost of 5-6 thousand EUR is something everyone should be able to afford, which is peanuts compared to the total construction cost, but often people prefer to save here and rather spend on some cosmetic feature like better tiles or sanitary fittings...
My system has been running flawlessly for two years now... but it is like a car... maintenance is required... for example, changing filters about every 6 months (cost is negligible since the filter material costs about 10 EUR per square meter [~1 EUR per filter])... simply vacuum the valves regularly, and a thorough cleaning of the ducts should be done every 10 years... there are specialist companies for this, no need to open walls or ceilings, the valves can simply be unscrewed to access the ductwork... you should anyway have access to the ventilation unit itself.
If the system is properly installed, you don’t have to tear open ceilings or walls later... if something breaks, it will be the ventilation unit itself... and, like any electronic device, it can fail suddenly, but since the technology is relatively simple, every ventilation technician can obtain and install replacement parts.
Blockages in the ventilation ducts are practically impossible because the ducts are adequately sized, and filters or grilles should be installed at all inlet and outlet points... Of course, if someone deliberately stuffs something in, problems can happen as well.
At least that has been my experience over the past few years... with the many standard houses being built today, something is installed that roughly fits and can provide the heating capacity needed...(on paper) but in reality, the electric heating element runs at low temperatures, and of course, it consumes a significant amount of energy...
So, in my opinion, an air source heat pump is a very expensive heating option nowadays, because, as I said, most are installed following a standard template...
A geothermal or groundwater heat pump is, of course, a completely different matter.
Regarding ventilation:
A central ventilation system is practically essential in highly insulated and airtight houses today... anyone who still does not understand this cannot really be helped... since almost no one realistically maintains the recommended ventilation intervals, and if construction damage occurs, the builder is off the hook because it is often said that the "ventilation intervals were not followed."
However, moisture must be removed, and assuming you are employed (which I think most people are when building a house), you simply cannot ventilate 3-4 times a day because you are not home...
I do not regret my decision to have a central controlled ventilation system installed during the construction two years ago... the additional cost of 5-6 thousand EUR is something everyone should be able to afford, which is peanuts compared to the total construction cost, but often people prefer to save here and rather spend on some cosmetic feature like better tiles or sanitary fittings...
My system has been running flawlessly for two years now... but it is like a car... maintenance is required... for example, changing filters about every 6 months (cost is negligible since the filter material costs about 10 EUR per square meter [~1 EUR per filter])... simply vacuum the valves regularly, and a thorough cleaning of the ducts should be done every 10 years... there are specialist companies for this, no need to open walls or ceilings, the valves can simply be unscrewed to access the ductwork... you should anyway have access to the ventilation unit itself.
If the system is properly installed, you don’t have to tear open ceilings or walls later... if something breaks, it will be the ventilation unit itself... and, like any electronic device, it can fail suddenly, but since the technology is relatively simple, every ventilation technician can obtain and install replacement parts.
Blockages in the ventilation ducts are practically impossible because the ducts are adequately sized, and filters or grilles should be installed at all inlet and outlet points... Of course, if someone deliberately stuffs something in, problems can happen as well.
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