Thermostat or receiver has a burnt smell or visible scorch marks.

Critical safety warning: Immediately switch off power at the fused spur and the consumer unit. Do not continue using the system until it has been inspected. Risk of fire or electric shock.

Steps:

• 1. Do not open if charred: If the casing is melted or severely burnt, do not attempt internal inspection yourself.
• 2. Visually inspect wiring (if safe): With power off, check for obvious loose or discoloured wires at the receiver terminals.
• 3. Do not re-energize: Do not turn the power back on until a qualified engineer has inspected and replaced any damaged components.

When to call a professional: This fault must be handled by a qualified heating engineer or electrician. The affected Baxi module will need replacement and wiring must be checked for safety.