Hello,
Hello, I have now received a demand of 8.8 kW from the heating installer based on the heating load calculation (KfW 55, HRB, underfloor heating complete, 170 sqm living area).
Is a controlled residential ventilation with/out heat recovery planned? Did the installer create this themselves, or is it from a system partner?
...However, the calculation did not take into account that we have also planned a water-based fireplace, which we will use daily in winter (wood available for free) and thus want to heat for heating and hot water preparation (200l buffer tank planned).
Here, one must differentiate, for example, between KfW certificates (10% allowed) and reality! In reality, the creditable share is usually somewhat higher, depending on the boundary conditions. Whether a 200l buffer is sufficient here, I rather doubt, but it depends on the specific boundary conditions! An exact calculation apparently does not exist ;-)
The higher the energetic share of wood combustion within the annual balance, the less worthwhile the rather high investment share for a brine water heat pump!
...Now we have been offered a brine-water heat pump with 10 kW output. The question now is, do you think that is oversized due to the fact of supplemental heating? Would a pump with 8 kW also be sufficient?
Could be, certainly not necessarily! What if no one can burn wood in case of illness? Then the brine heat pump is finished, and sustainably so, because the source was overloaded and this fact will subsequently be taken very badly!
Important for a brine heat pump is the guaranteed and sustainable yield (power, energy) of the source. For this, one would have to know the actual demand (power, energy) for heating and hot water. How high is that?
Also, one should clearly separate between instantaneous power and energy in the annual balance! ;-)
This combination is a compromise that presumably can hardly be economically represented overall.
...The pump would have its "main operating time" in summer for hot water preparation (heating is rather less in summer). In winter, the heat would mainly come from the fireplace and the heat pump would only step in if the buffer with the "fireplace water" is empty.
"Winter" and "summer" are not reliable terms energetically. From an energetic point of view, only annual temperature hours count!
Example:
...The fireplace has an output of 5 kW water output and 7 kW direct output. Thank you very much for your opinions!
7 kW in the installation room can quickly become a considerable problem. How high is its room heating load?
Best regards