Furnace shows power supply or polarity error, may not start or may behave erratically

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Incorrect live/neutral polarity, Loose mains terminal connections, Voltage outside specification, Shared neutral issues

Safety: Only a qualified electrician should work on mains wiring.

User check: Confirm that the correct circuit breaker is on and that there are no obvious signs of damage to the fused spur or plug.
Professional checks: An electrician should verify correct polarity, earth continuity, and supply voltage at the Baxi mains terminal block.
Tighten terminals: Loose live or neutral connections can cause intermittent faults and overheating; they must be tightened to specification.

Hard 4/5

Mains Terminal Block / Power Supply

Check Price on Amazon

We may earn a commission from links on this page.