Hello,
After the first few days in my new home, I’m having some issues with the heating system. Somehow, it feels like something isn’t working 100%... it heats very irregularly. In my experience, it only heats properly when as many rooms as possible are set to flow. Once most rooms have reached their temperature and only 1 or 2 are open, the system quickly cycles on and off...
- We have about 140 sqm (1507 sq ft) of floor area
- Underfloor heating throughout the entire house
- A Junkers Cerapur ZBS 22/100 S-3 MA gas boiler with hot water generation (22 kW)
- 17.5 cm (7 inches) calcium silicate stone + 14 cm (6 inches) external thermal insulation composite system (ETICS) (no special energy-saving regulations)
As mentioned, when only a few heating circuits are open, the boiler turns on (starting at about 25°C (77°F) flow temperature), heats up quickly (up to about 45°C (113°F) flow temperature), then drops off rapidly and starts again. So the heating circuits are only heated sporadically...? If I turn on more heating circuits, the warm-up time is longer and it gets warm... is the boiler oversized, since it heats single rooms poorly?
After the first few days in my new home, I’m having some issues with the heating system. Somehow, it feels like something isn’t working 100%... it heats very irregularly. In my experience, it only heats properly when as many rooms as possible are set to flow. Once most rooms have reached their temperature and only 1 or 2 are open, the system quickly cycles on and off...
- We have about 140 sqm (1507 sq ft) of floor area
- Underfloor heating throughout the entire house
- A Junkers Cerapur ZBS 22/100 S-3 MA gas boiler with hot water generation (22 kW)
- 17.5 cm (7 inches) calcium silicate stone + 14 cm (6 inches) external thermal insulation composite system (ETICS) (no special energy-saving regulations)
As mentioned, when only a few heating circuits are open, the boiler turns on (starting at about 25°C (77°F) flow temperature), heats up quickly (up to about 45°C (113°F) flow temperature), then drops off rapidly and starts again. So the heating circuits are only heated sporadically...? If I turn on more heating circuits, the warm-up time is longer and it gets warm... is the boiler oversized, since it heats single rooms poorly?
S
Sebastian7918 Jan 2016 21:363.6 kW at design temperature? We have the same dimensions but reach 8.1 kW...
EDIT: So, design temperature – calculated yourself? What output does your heating system have?
EDIT: So, design temperature – calculated yourself? What output does your heating system have?
Yes, I calculated it myself and was quite meticulous, creating a detailed calculation.
But the result also matches the measurements; the house has been standing for a while now, and I’ve been logging temperatures, consumption, etc. It’s even slightly better, though not significantly. The heating system has 5.8 kW at B0W35. I didn’t want less because of the domestic hot water, to avoid the storage tank taking too long to heat up. With a bit of tuning (hysteresis and compressor lockout), the unit cycles very reasonably—when it’s warm, it doesn’t cycle too often, but it cycles often enough to keep the cycle times from becoming too long.
Edit: Design temperature -14°C (7°F).
But the result also matches the measurements; the house has been standing for a while now, and I’ve been logging temperatures, consumption, etc. It’s even slightly better, though not significantly. The heating system has 5.8 kW at B0W35. I didn’t want less because of the domestic hot water, to avoid the storage tank taking too long to heat up. With a bit of tuning (hysteresis and compressor lockout), the unit cycles very reasonably—when it’s warm, it doesn’t cycle too often, but it cycles often enough to keep the cycle times from becoming too long.
Edit: Design temperature -14°C (7°F).
S
Sebastian7918 Jan 2016 21:59Ok, I'm just surprised that our DIN calculation (adjusted for different indoor temperatures, including controlled residential ventilation and hallways) resulted in such a much higher value.
I have also taken all of this into account, no idea about DIN standards, I just followed the principles of physics. But the dimensions alone don’t tell the whole story. For example, we have no bay windows or anything similar, just a completely rectangular building shape. The roof is basically double insulated at the top because of the controlled residential ventilation system—once at the ceiling of the upper floor and then fully between the rafters. In the children’s room/office, there are no floor-to-ceiling windows (although the children’s rooms have taller windows with a fixed lower part, so still less window area), because I see a need for space for furniture, and for a desk (at least mine), I prefer it to be in front of a regular window. The basement level is basically entirely below ground in terms of height. Maybe these kinds of details explain the difference?
S
Sebastian7918 Jan 2016 22:16Well, no idea – the values are taken from the thermal insulation calculation according to the energy saving regulations, which already include the components used.
What Ht value do you have? That is actually quite crucial...
What Ht value do you have? That is actually quite crucial...
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