Glow worm Fuel saver 65F won't fire up

[Chrisa72]

Both motorised valves are functioning correctly i.e. opening and closing and operating microswitch powering pump and boiler feed. Pump operating normally. Operation of boiler became eratic last week and failed to fire up in the morning on the programmer. Checked overheat reset button beneath boiler control box, had not activated. Then for unknown reason was ok for two or three days but has now packed up completely. Flue fan operates when the boiler stat is turned up and stops when turned back to zero. Checked operation of the two twin contact solenoid switches for operation. When viewed from the top, looking down onto the pcb the left hand solenoid contacts close when boiler turned on via the boiler stat. When the HT lead from the ignighter is earthed via metal surface of boiler the right hand solenoid switch contacts close and open again momentarily when the ht lead is removed from touching a metal component of the boiler. I have checked the operation of the air pressure switch but not measures the operating pressures and this appears to operating satisfactorily. Basically when I fire up the boiler, the motorised valves operate when the cylinder and rooms are calling for heat, the pump operates as does the flue fan, the next thing that normally happens is that the ignighter starts clicking, the gas solenoid valve opens and away it goes. I suspect it may be the ht transformer on the pcb but I don't want to make an expensive mistake. Any clues or comments please?

 

[sniper100]

Hi did you get this problem sorted? If so How? I have some ideas but due to the date I hope it will have been done by now. you don`t mention actually checking the vacuum by sucking the air pressure tube, was it the fan being inefficient?

 

[Chrisa72]

Hi Sniper 100, Thank you for your interest. Yes, I have managed to get the wretched thing sorted but not I fear without un necessary expense. The problem I believe as I had stated in the symtoms started out as being intermitent culminating in complete failure. I must admit that prior to going out and buying a replacement PCB I had not checked the air pressure switch diaphragm operation. I changed the PCB, still no joy, checked the pressure switch by as you say, sucking on the tube and hey presto the spark generator was spaking at the pilot light. However, once reassembled - nothing. Now I found the fan not to be working. Carried out simple continuity tests and found that I had got electricity at the choc block connector connecting the fan tails to the boiler wiring but nothing to the fan its self. You're probably there before me already at this point, the lack of juice was due to the cable being inserted too far into the connector block and the screw simply being tightend down on to the insulation!! Re made the connection and Bob's your uncle! Success I still dont know for certain of course whether this was a fault that had lain dormant for the best part of fifteen years or one I had created recently whilst trying to find the problem and to be honest I could not be fagged with taking the new PCB out and replacing it with the old one, I could not have got a refund and anyway, its working!! Thanks for your interest .
Kind regards.

Chris A