M
merlin66726 Jul 2013 20:24Hello everyone,
We are currently planning a new single-family house and are in the final stages of completing the floor plans. We are quite satisfied so far, but I am a bit uncertain about the heating system. I understand that a precise design according to ÖN/ or EN standards cannot be done here (it’s not just a couple of clicks).
Here are the key data:
Gross floor area 188m² (2023 ft²), gross volume 608m³ (21,472 ft³), building envelope surface 448m² (4822 ft²), compactness (A/V ratio) 0.74, average U-value 0.22 W/m²K, according to the energy certificate the building’s heating load Ptot with 0.5 air changes per hour is 5.76 kW.
Heating is via underfloor heating, plus there will be a mechanical ventilation system with a heat exchanger.
Regarding the location:
Standard outdoor temperature is -12.3°C (10°F), heating days 175 days, heating degree days 3791 Kd, lowest temperature reached -25.2°C (-13°F) over the past 30 years, -20°C (-4°F) is regularly reached every winter, with 122 frost days and 26 ice days per year.
On the other hand, the summer extremes reach up to 37.2°C (99°F), and in recent years we have averaged about 20 days per year (mostly in two periods) where the daily maximum temperatures exceed 30°C (86°F). Because of this, I am seriously considering the option of cooling with the heat pump.
Our main issue is this:
I am not entirely sure which heat pump to choose.
How suitable is a ground collector (horizontal collector) given these parameters? We have 933m² (10,045 ft²) of land. The soil is clayey and wet, which from what I have found so far, is actually one of the best conditions for a horizontal ground collector. However, I have some concerns about longer winters or thick snow cover (there have been several winters recently where we had continuous snow cover from the end of November to mid-April). This is, of course, combined with extremely low outdoor temperatures for extended periods.
On the other hand, an air-source heat pump is also being considered, but I have another question:
Is it advisable to aim for monovalent operation for as long as possible, meaning relying solely on the heat pump without backup heating, but sizing the heat pump somewhat larger?
Is it acceptable to add the output capacity of the pre-heating coil (preheater) to the heating output? I assume yes, but:
What about defrosting the evaporator—could this cause problems if the preheater is included?
We are currently planning a new single-family house and are in the final stages of completing the floor plans. We are quite satisfied so far, but I am a bit uncertain about the heating system. I understand that a precise design according to ÖN/ or EN standards cannot be done here (it’s not just a couple of clicks).
Here are the key data:
Gross floor area 188m² (2023 ft²), gross volume 608m³ (21,472 ft³), building envelope surface 448m² (4822 ft²), compactness (A/V ratio) 0.74, average U-value 0.22 W/m²K, according to the energy certificate the building’s heating load Ptot with 0.5 air changes per hour is 5.76 kW.
Heating is via underfloor heating, plus there will be a mechanical ventilation system with a heat exchanger.
Regarding the location:
Standard outdoor temperature is -12.3°C (10°F), heating days 175 days, heating degree days 3791 Kd, lowest temperature reached -25.2°C (-13°F) over the past 30 years, -20°C (-4°F) is regularly reached every winter, with 122 frost days and 26 ice days per year.
On the other hand, the summer extremes reach up to 37.2°C (99°F), and in recent years we have averaged about 20 days per year (mostly in two periods) where the daily maximum temperatures exceed 30°C (86°F). Because of this, I am seriously considering the option of cooling with the heat pump.
Our main issue is this:
I am not entirely sure which heat pump to choose.
How suitable is a ground collector (horizontal collector) given these parameters? We have 933m² (10,045 ft²) of land. The soil is clayey and wet, which from what I have found so far, is actually one of the best conditions for a horizontal ground collector. However, I have some concerns about longer winters or thick snow cover (there have been several winters recently where we had continuous snow cover from the end of November to mid-April). This is, of course, combined with extremely low outdoor temperatures for extended periods.
On the other hand, an air-source heat pump is also being considered, but I have another question:
Is it advisable to aim for monovalent operation for as long as possible, meaning relying solely on the heat pump without backup heating, but sizing the heat pump somewhat larger?
Is it acceptable to add the output capacity of the pre-heating coil (preheater) to the heating output? I assume yes, but:
What about defrosting the evaporator—could this cause problems if the preheater is included?
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