i have a baxi boiler i fitted 9yrs ago and got a corgi guy to connect up the gas and check .it has been great untill about a year ago when the pcb failed i repaired the pcb and all was fine for a year. now rain got into the flue and soaked the pcb which blew the fuse so i blew the pcb out with a compressor sprayed wd40 on it put a fuse in and all was fine again for a week .now the fan is starting and stopping every second and it wont fire up? i have checked all connections and the aps pipes all seem ok if you turn it on you can see the aps pull in and activate the micro switch then it just keeps cycling the fan on and off .Do you think the pcb has finally had it? the fan is spinning ok nice and fast is there anything else i should check pump is pumping

mike, August 2008

Well thought it was fixed it seems that the pump will not power off now it runs forever regardless if the boiler is hot or cold the only way to stop it is to turn the mains off? it runs if the boiler control is off and the heater controls are off and if the overheat and thermostat on the pipes are off it carries on running could this be a faulty over run relay on the reconditioned pcb i have just fitted?

mike, August 2008

It was indeed the pcb got an exchange 1 for £30 and all is happy again.

mike, August 2008

faulty fan relay on pcb perhaps, if fan is spinning in bursts it has sod all to do with aps and pipes etc as they are there to prove fan is working before boiler will fire up, generally pump is first in sequence so its all looking very pcb, since its been repaired twice already maybe time to bite the bullet and new one.

that would be my thoughts anyhoo, someone else may have experienced this but i aint so thats my "ahem" educated guess via t'internet

iain, August 2008