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
T_im_Norden9 Nov 2020 20:31Anhydrite screed is generally considered well suited for underfloor heating systems because of its good thermal conductivity.
So, I now have the quote from the heating technician. It looks quite reasonable. However, I’m in a dilemma.
He wants to install the Vaillant Arotherm VWL 105/6 A, which has a heating capacity of 10 kW, significantly larger than our heating demand of 5.9 kW for heating + 0.8 kW (estimated) for domestic hot water = 6.7 kW at NAT.
“Actually,” the smaller VWL 75/6 A should easily be sufficient and even have some reserve capacity. Based on what I’ve read here, it still seems to be oversized.
However, I’m now unsure about the pump flow rates.
VWL 105/6 A: 1418 liters per hour (788 mbar)
VWL 75/6 A: 790 liters per hour (640 mbar)
Heating load calculation resulted in:
Pressure loss of the most unfavorable circuit: 7879 Pa
Pump head: 0.79 m (2.6 ft)
Total flow rate: 22.2 liters per minute (1331.3 liters per hour)
As a layperson, I conclude that although the heating capacity of the smaller heat pump would be more than sufficient, the circulation pump might be too weak to push the warm water through my many and long heating circuits – meaning I would have to bite the bullet and choose the larger unit, with the risk of short cycling etc.
Have I understood this correctly @Daniel-Sp @Mycraft @T_im_Norden, or am I mistaken?
Is there any way to find out how far the larger Vaillant model can modulate down?
He wants to install the Vaillant Arotherm VWL 105/6 A, which has a heating capacity of 10 kW, significantly larger than our heating demand of 5.9 kW for heating + 0.8 kW (estimated) for domestic hot water = 6.7 kW at NAT.
“Actually,” the smaller VWL 75/6 A should easily be sufficient and even have some reserve capacity. Based on what I’ve read here, it still seems to be oversized.
However, I’m now unsure about the pump flow rates.
VWL 105/6 A: 1418 liters per hour (788 mbar)
VWL 75/6 A: 790 liters per hour (640 mbar)
Heating load calculation resulted in:
Pressure loss of the most unfavorable circuit: 7879 Pa
Pump head: 0.79 m (2.6 ft)
Total flow rate: 22.2 liters per minute (1331.3 liters per hour)
As a layperson, I conclude that although the heating capacity of the smaller heat pump would be more than sufficient, the circulation pump might be too weak to push the warm water through my many and long heating circuits – meaning I would have to bite the bullet and choose the larger unit, with the risk of short cycling etc.
Have I understood this correctly @Daniel-Sp @Mycraft @T_im_Norden, or am I mistaken?
Is there any way to find out how far the larger Vaillant model can modulate down?
T
T_im_Norden13 Nov 2020 12:51Vaillant specifies a maximum flow rate of 1,205 liters for the 75 model.
You are slightly exceeding that.
The 55 model goes down to 2.10 meters (6.9 feet).
The 75 model goes down to 3 meters (9.8 feet).
The 105 model goes down to 5.40 meters (17.7 feet).
As a layperson, I would actually tend towards the 55, but the flow rate no longer fits there.
You are slightly exceeding that.
The 55 model goes down to 2.10 meters (6.9 feet).
The 75 model goes down to 3 meters (9.8 feet).
The 105 model goes down to 5.40 meters (17.7 feet).
As a layperson, I would actually tend towards the 55, but the flow rate no longer fits there.
Tolentino schrieb:
According to the seasonal performance factor calculator, the 55 at least does not achieve 4.5.Thanks for the note. With my supply temperature and domestic hot water share, the 75 already reaches a seasonal performance factor of 4.7.Similar topics