glow worm 60b ff bafflement, stumped me!!

[REDSAW]

glow worm 60b ff fault.

cant work this one out so some help be appreciated please.
boiler fires and runs ok. sometimes it comes on for 10-20 mins then takes an hour to re-light. rads get very hot. pumped heating and pumps ok. gravity hot water. no stats. randel 103 controls. fan ok. changed thermistor although it reads 15kohm about .7ohm difference from new one.
totally stumped although there is good heat in the rads they will go stone cold before heating kicks back in by turning off boiler and back on (customers account).

aint got a scooby????????????????

 

[Billy Bob Bob]

possible thermostat fault

 

[REDSAW]

wheres the thermostat, the pcb?

 

[Billy Bob Bob]

wheres the thermostat, the pcb?

think so not done a lot on this boiler,but the electronic bermudas suffer a similar fault,normally pcb

 

[heliotrope]

Might be worth checking the gas valve solenoids.

Could be going open circuit when getting warm/hot.

 

[zeebeedee]

Any trv's on the system?

 

[REDSAW]

Might be worth checking the gas valve solenoids.

Could be going open circuit when getting warm/hot.

hmmm, interesting thought
no trv's

got a quote for the pcb @£300, think the old dear would have a fit with that;/

 

[bigads28]

Going by what you've said I'd change the board, you should find it for about £180 though.

 

[arran197]

Once the boiler gets up to temperature, does the pump continue to run? I had an old Potterton Prima that had the pump wired to the boiler, but the power to the pump would only come on when the stat kicked in, so once the boiler stat got up to temperature, the pump would switch off and it would take ages for the system to naturally cool down and the boiler to kick back in again. It'd been like it for years and the rads went cold before coming back on.

 

[REDSAW]

once the boiler gets up to temperature, does the pump continue to run? I had an old potterton prima that had the pump wired to the boiler, but the power to the pump would only come on when the stat kicked in, so once the boiler stat got up to temperature, the pump would switch off and it would take ages for the system to naturally cool down and the boiler to kick back in again. It'd been like it for years and the rads went cold before coming back on.

yes pump still runs and rads chill down

 

[REDSAW]

asked a mate of mine to take over as i have a personal problem to deal with so not doing much this week.

luckily, he had one of these before and called the tech line who told him to fit new board at £300. he told them he wasnt prepared to do that only as a last resort and asked if there was something else to check first. they told him to check voltage return on fan. he tells me theres a thermal cut out built into the fan and recons thats causing it, so we shall see!!