Problem Solution
No heating Domestic flow switch can stick on, disconnect wire and if heating comes on change flow switch
Intermittent faults

Primary flow switch can stick on, off, and in betweenm there is a retro fitting spring available to make sure it returns to the correct position

Lockout Ignition boards can give a weak spark


Combi 80 and 105


Problem Solution
Overheat problems There is a strainer filter inisolation valve on the right in the return isolation valve, these clog up
Lockout on heating

Check low gas setting on modureg is set correctly

Low water temperature after new PCB Check potentiometer knob is not fitted 180 degrees the wrong way, there is a right and wrong way to fit these


Combi Instant


Problem Solution
High pitched squealing noise There was a modification by Baxi in 2003 to the differential and diverter valve o-rings
No or poor hot water

Check the water differential valve is operating correctly, if it fails to work the water will bpyass the plate heat exchanger and go round the main heat exchanger and expansion storage vessel only.

Reset problem new PCB Hold in the reset position for at least a minute as they normally come in the failed position from the manufacturers.
Expansion Vessel The instant range has an integrated storage within the expansion vessel, there are two connections not one as per normal.
Reset problem

Turn the hot water and heating potentiometer to full, and run a tap, now hold reset position for five seconds


Duo Tec Combi HE


Problem Solution
E133 Spark electrode can bend causing incorrect spark gap