Hello everyone,
We are building a semi-detached house with a total heated area of approximately 460 sqm (4,951 sq ft). The building will be constructed to KFW 55 standard. Both units will have a central ventilation system from Zehnder with heat recovery. According to our energy certificate, one half of the house has a heating demand of 10 kW and the other 7 kW.
The heated area includes the two basements, which are not occupied but only moderately heated (partly used for storage).
We are producing everything separately except for the boiler, specifically:
A shared Fröling PE1 boiler without a particle filter
and for each unit:
A solar collector with vacuum tubes and a gross surface area of 10 sqm (108 sq ft)
A 1000-liter (264-gallon) hygienic storage tank with two solar coils, one at the top and one at the bottom.
The system will be set up so that the solar collectors heat the respective buffer tanks of each half, and the boiler will only activate when one of the buffer tanks gets too cold and then heat both to the target temperature.
Now the big question is: Which PE1 boiler should we choose? We want to avoid being cold, but at the same time, not oversize the boiler given pellet consumption and wear from frequent cycling.
I am not sure how much emphasis we can put on the figures in the energy certificate and how the domestic hot water consumption needs to be factored in here.
I look forward to your ideas and hope I haven’t forgotten any details. Otherwise, I’m happy to provide more information.
We are building a semi-detached house with a total heated area of approximately 460 sqm (4,951 sq ft). The building will be constructed to KFW 55 standard. Both units will have a central ventilation system from Zehnder with heat recovery. According to our energy certificate, one half of the house has a heating demand of 10 kW and the other 7 kW.
The heated area includes the two basements, which are not occupied but only moderately heated (partly used for storage).
We are producing everything separately except for the boiler, specifically:
A shared Fröling PE1 boiler without a particle filter
and for each unit:
A solar collector with vacuum tubes and a gross surface area of 10 sqm (108 sq ft)
A 1000-liter (264-gallon) hygienic storage tank with two solar coils, one at the top and one at the bottom.
The system will be set up so that the solar collectors heat the respective buffer tanks of each half, and the boiler will only activate when one of the buffer tanks gets too cold and then heat both to the target temperature.
Now the big question is: Which PE1 boiler should we choose? We want to avoid being cold, but at the same time, not oversize the boiler given pellet consumption and wear from frequent cycling.
I am not sure how much emphasis we can put on the figures in the energy certificate and how the domestic hot water consumption needs to be factored in here.
I look forward to your ideas and hope I haven’t forgotten any details. Otherwise, I’m happy to provide more information.
O
Oetzberger8 Oct 2021 09:28With 460 kW of heated screed and a proper hydraulic balancing, a minimum output of 3 to 4 kW is definitely not oversized. However, if the hydraulic balancing is done only half-heartedly and too many ERRs restrict the flow during normal operation, the heating system will still be somewhat strained.
haraldv schrieb:
Of course, a heating load calculation was done, but it refers to the coldest day.That is normal. Still, I cannot believe 18 kW. The unit is too large and probably half of the heating circuits were throttled by the ERR, which leads to the described dilemma.