F.57
FAULT CODE
Vaillant
Comfort Mode Heat Demand Not Met
Low Severity
DIY Check Possible
The boiler is running in comfort (reduced loss) mode but cannot meet the heat demand.
Step-by-Step Fix Guide
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Step 1
Check that the comfort mode settings are configured correctly in the boiler menu
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Step 2
Ensure the flow temperature setpoint is high enough for the system
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Step 3
If the issue persists, a Gas Safe engineer should check system sizing
Gas Safe Reminder
Work on gas appliances must be carried out by a Gas Safe registered engineer. The steps above cover safe checks a homeowner can perform - any internal component replacement requires a qualified professional. If in doubt, always call an engineer.