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
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
T_im_Norden schrieb:
The 55 model is included in the list of eligible units.
aroTHERM plus VWL 55/6 A 230V S2Yes, I’ve seen that. But I have to run it with a 30°C (86°F) supply temperature to achieve the BAFA annual performance factor at -10°C (14°F) outside temperature. Unfortunately, that won’t be possible with our build.From my perspective, if our oversized heat pump finally fails after more than 15 years (at least, hopefully), I can then install a properly sized one based on practical experience, without considering BAFA requirements, the general contractor, the heating engineer, or warranty issues.
T
T_im_Norden14 Nov 2020 12:14Ask your office if they can calculate the impact of lowering the room temperature. With the same pipe layout, this should reduce the calculated flow temperature, and everything should fit accordingly. Otherwise, suggest to your wife to invest the money saved on the Daikin system in shoes; maybe then she will accept the appearance.
I have a calculation based on a 30°C (86°F) supply temperature. I would need a pipe spacing of 10cm (4 inches) everywhere, and 5cm (2 inches) in the bathrooms, but despite having wall heating, I still have a heating deficit of 300W in each bathroom. The basement rooms would each have a deficit of -200W (with a 20°C (68°F) target temperature).
The engineering office strongly advised against using this supply temperature. I would be operating very close to the limits in every area. There would be significant heating deficits in the bathrooms and basement, and I would also need a flow rate of over 1300 liters per hour (about 570 gallons per hour) for the heating circuit pump.
By the way, the “shoe” argument definitely doesn’t get me anywhere. The discussion immediately shifts to wanting both the nice heat pump AND the shoes. Then suggestions like saving money on bicycles or buying fewer computer gadgets come up. The discussion usually ends very quickly and unpleasantly for me. 😉
The engineering office strongly advised against using this supply temperature. I would be operating very close to the limits in every area. There would be significant heating deficits in the bathrooms and basement, and I would also need a flow rate of over 1300 liters per hour (about 570 gallons per hour) for the heating circuit pump.
By the way, the “shoe” argument definitely doesn’t get me anywhere. The discussion immediately shifts to wanting both the nice heat pump AND the shoes. Then suggestions like saving money on bicycles or buying fewer computer gadgets come up. The discussion usually ends very quickly and unpleasantly for me. 😉
T
T_im_Norden14 Nov 2020 12:58The BAFA only wants a number on paper; if you later have to set the supply temperature to 33°C (91°F) because it gets too cold, they don’t care.
That’s the crazy thing about the subsidy—if you have an old building and consume a lot of energy, you can quickly achieve a good annual performance factor. But if you have a well-insulated house and use little energy, it becomes increasingly difficult to reach a good annual performance factor, because the domestic hot water preparation worsens the values.
That’s the crazy thing about the subsidy—if you have an old building and consume a lot of energy, you can quickly achieve a good annual performance factor. But if you have a well-insulated house and use little energy, it becomes increasingly difficult to reach a good annual performance factor, because the domestic hot water preparation worsens the values.
D
Daniel-Sp14 Nov 2020 13:15I agree. Adjust the calculation to fit the BAFA subsidy requirements. How you operate the system later? No one cares about that. It’s the same with ERR. You have to install it, and you are allowed to dismantle it afterwards...
I have the feeling that my project is becoming increasingly complex here.
I’m afraid there is no optimal solution for me. My wife has forbidden me from using Daikin, and Vaillant only offers heat pumps with weak heating circuit pumps. The 55 model only has a volume flow of 860 liters per hour. I can’t use that for my house, or I would need to significantly increase the temperature difference.
I’m afraid there is no optimal solution for me. My wife has forbidden me from using Daikin, and Vaillant only offers heat pumps with weak heating circuit pumps. The 55 model only has a volume flow of 860 liters per hour. I can’t use that for my house, or I would need to significantly increase the temperature difference.
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