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?
Has the heating system been commissioned with all necessary inspections, acceptance certificates, and specialist contractor certifications, including the hydraulic balancing? Has a heating load calculation and system sizing been carried out beforehand? The burner capacity seems oversized to me. As a rough estimate, the heat generator should have approximately the capacity of (140m2 x 70 W/m2) + (4 x 200 W for domestic hot water preparation / 4 people) = 9,800 W + 800 W = 10.6 kW.
With a 22 kW burner capacity and a potentially undersized buffer tank, the system cycles frequently. This can happen if the entire system has not been properly calculated and sized. Contact the heating specialist company or the general contractor / main contractor who built the house, report the insufficient performance, and request the necessary calculations and the above-mentioned specialist contractor certificates.
You are within the warranty period of 4 years / VOB or 5 years according to the Building Code, and hopefully, you have enforced a warranty retention of at least 5% of the invoiced amount for such cases.
With a 22 kW burner capacity and a potentially undersized buffer tank, the system cycles frequently. This can happen if the entire system has not been properly calculated and sized. Contact the heating specialist company or the general contractor / main contractor who built the house, report the insufficient performance, and request the necessary calculations and the above-mentioned specialist contractor certificates.
You are within the warranty period of 4 years / VOB or 5 years according to the Building Code, and hopefully, you have enforced a warranty retention of at least 5% of the invoiced amount for such cases.
Hello,
If I remember correctly, I'm not really familiar with Junkers, but the heating curve can only be adjusted further down in the expert mode, or the option can be enabled there.
Additionally, it is also possible in the expert mode to reduce the output during heating operation by adjusting the fan speed.
Olli
If I remember correctly, I'm not really familiar with Junkers, but the heating curve can only be adjusted further down in the expert mode, or the option can be enabled there.
Additionally, it is also possible in the expert mode to reduce the output during heating operation by adjusting the fan speed.
Olli
wpic schrieb:
Has the heating system been commissioned with all necessary inspections, acceptance certificates, and specialist contractor confirmations, including the hydraulic balancing? Has a heating load calculation and system sizing been carried out beforehand? The burner capacity seems oversized to me. As a rough estimate, the heat generator should have a capacity approximately equal to (140m2 (1507 sq ft) x 70 W/m2 (21.9 W/sq ft)) + (4 x 200 W for domestic hot water preparation / 4 people) = 9800 W + 800 W = 10.6 kW.
With a 22 kW burner capacity and a possibly undersized buffer tank, the unit cycles frequently. This can happen if the entire system has not been properly designed and sized. Contact the heating specialist company or the general contractor who built the house, report the insufficient performance, and request the necessary calculations and the above-mentioned specialist contractor confirmations.
You are still within the warranty period of 4 years/VOB or 5 years according to building regulations and hopefully have enforced a warranty retention of at least 5% of the invoice amount for such cases.Which category in your calculation do the 70 watts refer to?
- Primary energy
- Final energy
- Heating demand
I have all three categories shown in my documents.
Musketier schrieb:
Why is it even heating up to 45 degrees? In my opinion, lower the heating curve and open the thermostats further or fully.
22 kW is definitely quite excessive.The temperature fluctuates, it depends on the outside temperature...there is an additional sensor on the outside wall...but it’s always around that range. The room controllers are set to almost 20 degrees everywhere...
wrobel schrieb:
Hello,
If I remember correctly, I’m not really familiar with Junkers, the heating curve can only be lowered further in the professional mode or the option to do so can be enabled there.
Additionally, it is also possible in the professional mode to reduce the output during heating operation by adjusting the fan speed.
OlliAnd what effect does lowering the heating curve have?
wpic schrieb:
Has the heating system been commissioned with all required inspections, acceptance certificates, and specialist contractor declarations, including hydraulic balancing? Has a heating load calculation and system sizing been done beforehand? The burner capacity seems oversized to me. Roughly estimated, the heat generator should have a capacity of about (140 m2 x 70 W/m2) + (4 x 200 W for domestic hot water preparation/4 persons) = 9,800 W + 800 W = 10.6 kW.I have an acceptance certificate from the chimney sweep as well as a specialist contractor declaration...for all the others, I would have to check.
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