glow worm fuel saver 45f boiler cutting out

[godwinap]

glow worm fuel saver 45 f boiler keeps cutting out when main flame is on,

what happens is fan runs, ignition lights pilot, main boiler flame runs for approx 45 secs then fan stops and main flame goes out, it will go through this process over again and do exactly the same again,

have checked the fan and air flow switch ok

overtemp stat ok

diverter and pump has got waterflow

any advice would be appreciated as now run out of ideas and getting desperate!!!!!!!!!

 

[Boilerman2]

How warm is the boiler water after 45secs? sounds like a faulty Boiler Control Thermostat fault

 

[godwinap]

inlet and outlet pipes are cold even after firing up boiler flame a dozen times

 

[godwinap]

checked thermostat while the boiler is running during the 45 sec run time , themostat seems to be ok turning boiler on and off whilst running

 

[godwinap]

noticed on another post similar problem, they found fan cutting out, so took out fan ran it on the worktop direct from 240v socket and it cut out after about 40 secs.

bought new fan now all ok