KfW40 house offer with AWP and controlled residential ventilation, is it any good?

  • Erstellt am 2019-05-25 21:19:41

querys_

2019-05-25 21:19:41
  • #1
Hello everyone,
today a house offer came in from a prefabricated house provider.
They list the exhaust air heat pump Nibe F 750 with supply air module SAM 40 as heating. The maximum building heating load is supposed to be 7.5 kW.
Additionally, there is underfloor heating and a 180L hot water storage tank.
The house is located near Cologne/Bonn Airport (for climate reference) and is about 120 sqm in size (without basement).

I have already read a lot of negative things about exhaust air heat pumps, so again the question whether this thing is any good and if not, what would be an alternative and how much would that cost more?

Thank you very much!
 

lesmue79

2019-05-26 08:50:08
  • #2
Should the 7.5 kW be the heating load of the house? If so, I find that way too high for Kfw 40... If the 7.5 kW is the heating load that the heat pump can handle, I would also be cautious that this is not house sales marketing again.
 

querys_

2019-05-26 09:13:00
  • #3
I assume that it refers to the building, as it is written that way in the offer
 

Domski

2019-05-26 10:39:50
  • #4
Hardly any FH provider delivers a usable heating load calculation during the offer phase.

7.5kW is far too high for 120sqm KfW 40.

Exhaust air heat pumps are only suitable for passive houses. Please do not forgo water-bearing heating surfaces, as this is usually the consequence of offered exhaust air heat pumps.
 

querys_

2019-05-26 11:04:57
  • #5
Hydronic heating surface = underfloor heating? That would be planned anyway.

Instead of an exhaust air heat pump, an outdoor air heat pump would be better? Those are the devices that have a fan in front of the house? For example Nibe F2120?

What would be an acceptable heating load? What does the value actually refer to? Like 7.5kW per day, month, year?

I think I haven't quite understood the difference yet.
OHP = The waste heat from the house heats the domestic hot water and the heating circuit.
So if I need warm water, I unnecessarily extract a lot of heat from my house, which I then have to reheat. Possibly with electricity.

Air-to-air heat pump = I use the outside air to warm up my water (domestic hot water and heating water) inside. It actually doesn't matter how much heat I need in the house because there is enough air "outside."

In both cases, it is bad if it gets very cold outside?
 

boxandroof

2019-05-26 12:51:49
  • #6
An air-to-water heat pump is not bad if done well, on the contrary. Especially in your region. However, your offer does not sound like it is done well.

Heating load for your house no more than 4kW. The air-to-water heat pump should be modulating; then you can also take up to e.g. 6kW if nothing smaller is available. Otherwise, follow everything Domski has written.
 

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