S.31
FAULT CODE
Vaillant
Summer Mode — No Heat Demand
Low Severity
DIY Check Possible
Status code: The boiler is in summer mode (central heating switched off at controls or thermostat). Hot water is still available. Normal status.
Step-by-Step Fix Guide
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Step 1
If you want heating, check the room thermostat is calling for heat and the boiler mode selector is not set to summer/DHW only
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.