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?
It has been mentioned several times: Set all ERR to maximum and try to bring your house to a comfortable temperature by adjusting the heating curve and supply temperature setpoint. As long as the ERR are controlling automatically, nothing will improve.
However, it is clear that the heating system is really operating at the upper limit of its capacity. We have an 8.5 kW heat pump in a 2005 "older building" of the same size, and that is more than enough...
However, it is clear that the heating system is really operating at the upper limit of its capacity. We have an 8.5 kW heat pump in a 2005 "older building" of the same size, and that is more than enough...
Nordmann schrieb:
It has been mentioned several times: Set all ERR valves to maximum and try to achieve a comfortable temperature in your house by adjusting the heating curve and flow temperature setpoint.
As long as the ERR valves are regulating, it won’t work.
It is clear, however, that the heating system is really operating at its upper performance limit. We have an 8.5 kW heat pump in a 2005 "old building" of the same size. That’s more than enough...I’ve done that for now... All valves fully open and set the flow rate in the heating circuit pump (HKV) to 1 liter per minute (0.26 gallons per minute) initially... Lowered the design temperature (at -15°C (5°F)) from 45°C (113°F) to 35°C (95°F)... Now I’m waiting to see how the heat output develops... If rooms are too cold, the flow rate will be increased; if too warm, it will be lowered... Let’s see how the boiler’s behavior changes…
Direct heating curve adjustments don’t seem to be available on Junkers systems..?
Despite having 11 open heating circuits (which means a flow rate of 11 liters per minute), the boiler only heats for about 5 minutes at a time and then switches off... and after a few minutes, it turns back on again... the starting temperature is now around 23°C (73°F), and it heats up to about 32°C (90°F)... so adjusting the design temperature has already had some effect... but inside the building, the temperature is currently only around 18°C (64°F)... still too cold... so I will probably need to increase the flow rate a bit more...?
The pressure is currently just above 1 bar (14.5 psi)... could this be related? It should be around 1.5 bar (22 psi), right? The heating company will come again tomorrow or the day after... or does this not make much of a difference yet?
The pressure is currently just above 1 bar (14.5 psi)... could this be related? It should be around 1.5 bar (22 psi), right? The heating company will come again tomorrow or the day after... or does this not make much of a difference yet?
I have fully opened the flow to the warmest rooms (bathrooms, living room, kitchen) and then adjusted the heating curve accordingly.
In another forum, I read that the Junkers Cerapur has a base point and an end point.
The base point is the supply temperature needed at an outdoor temperature of 20°C (68°F) to heat the apartment. The end point is the supply temperature required at an outdoor temperature of -15°C (5°F) to heat the apartment.
If you move both points up or down, you shift the curve in parallel. If you move only one point up or down, you change the slope.
Basti2709 schrieb:
Direct heating curve settings don’t seem to be available with Junkers..?
In another forum, I read that the Junkers Cerapur has a base point and an end point.
The base point is the supply temperature needed at an outdoor temperature of 20°C (68°F) to heat the apartment. The end point is the supply temperature required at an outdoor temperature of -15°C (5°F) to heat the apartment.
If you move both points up or down, you shift the curve in parallel. If you move only one point up or down, you change the slope.
Musketier schrieb:
I turned the flow rate up to maximum in the warmest rooms (bathrooms, living room, kitchen) and then adjusted the heating curve accordingly.
I’ve done the same now... I’m currently at 17 liters per minute (4.5 gallons per minute) flow rate... unfortunately, I can only observe the heating durations in the evening.
What exactly does the boiler modulate based on? Which parameter tells it to operate at lower power? In my case, does it make sense to limit the maximum heat output? According to the default settings, it was like this:
Minimum heat output: 36%
Maximum heat output: 84% (now I have it set to 50%)
Would it therefore make sense to set the minimum (36%) equal to the maximum heat output (36%)? That would still be about 7.3 kW.
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