ᐅ Sizing of Air-to-Water Heat Pumps for New Construction

Created on: 6 Aug 2020 11:45
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Pixelsurium
Hello everyone,

we are planning a prefabricated house using timber frame construction. It will have 180 sqm (1,937 sq ft) of living space with underfloor heating, and about 230 sqm (2,475 sq ft) of usable area.
So far, the offer included an air-to-water heat pump from Daikin (Altherma 3R, formerly Rotex HPSU compact Ultra).

Now it seems that this unit might not have enough capacity (?) and as an alternative (additional cost around 4,000) we have been offered a "Wolf heat pump CHC Monoblock 10/300-35".

The Daikin is available in the 4-9 kW version—would that really be insufficient for this size? And what do you think about this offer?

I have the energy-saving regulation heat protection certification and a renewable energy heat law document available, if any information from those is needed.

Thank you very much!
Best regards
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Pixelsurium
9 Aug 2020 18:11
So you would prefer the Wolf CHC Monoblock over the Daikin 8kW if I can get it in the 7kW version rather than the 10kW?
Tolentino9 Aug 2020 18:22
Can someone knowledgeable here evaluate the Vaillant Arotherm 75/6?
It is supposed to easily achieve an annual performance factor of 4.6.
But in this forum, Vaillant is rarely mentioned in connection with heat pumps... is there a specific reason for that?
tomtom799 Aug 2020 19:11
What bothers me about the whole situation is the granny flat; if you ever get a bad tenant, the kilowatt hours just run up.

Make sure to install a heat meter, and 20-21 degrees Celsius (68-70°F) feels cold. Pay close attention to having a 5cm (2 inches) pipe spacing in the bathroom floor heating. Also, for the granny flat, have an additional heater on a separate electricity meter.
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Pixelsurium
9 Aug 2020 19:29
tomtom79 schrieb:

What bothers me about the whole situation is the separate apartment. If you ever get a bad tenant, the kilowatt hours will skyrocket.

Be sure to install a heat meter, and 20-21 degrees Celsius (68-70°F) feels cold. Pay close attention to keeping the pipe spacing in the bathroom at 5cm (2 inches). Also, for the separate apartment, have an additional heating system on a separate electricity meter.


Do you mean a separate air-to-water heat pump by additional heating? What is the reason for the 5cm (2 inches) spacing? Is it to make it warmer there?
tomtom799 Aug 2020 19:51
No, an electric auxiliary heater in the form of a towel radiator will then be powered by your electricity consumption and not by the output of the air-to-water heat pump.

By reducing the spacing of the heating circuit in the bathroom, you get more heat output at lower flow temperatures.
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Pixelsurium
9 Aug 2020 20:32
tomtom79 schrieb:

No, an electric backup heater in the form of a towel radiator will then draw power from your electricity supply, not from the capacity of the air-to-water heat pump.

By reducing the spacing of the heating coil in the bathroom, you get more heat output at lower flow temperatures.
All right, and where exactly should the heat meter be installed?