boiler acting up after new pcb installed......???

[sonofrob]

hello,,,i installed a new pcb today in my chaffoteaux britony 80,,,the only reason it needed a new pcb is the temperature spindle had broken off half way down the stem,,,long story the last owners had superglued the knobs to the spindles instead of replacing them,,,anyway,,,now thw new pcb is in- the boiler has started acting up,,,when first switched on it fires up in ch mode but appears to be only on low flame until you press the reset button then it goes into high flame???,,,and when you turn on the dwh when the ch is on then turn it off again it doesnt click back onto ch unless i reset again then it fires straight up???,,,but it goes straight onto high flame when dhw is turned on,,,it didnt have this problem with the old pcb so i took the new one out and replaced the old one to see what happened,,,when switched on with the old pcb in the flame was going from high to low every few seconds???the system does have a lot of **** in it as it has been negleted for a long time,,,i plan to get it all cleaned through etc once it is up and running correctly,,,any advice greatly appreciated................................

 

[Gasguru]

Doubt there's much wrong with the old pcb...I've yet to change them on these models.

Normal problems for these are sticking (and leaking) diverters, blocked heating return filter, iffy flow thermistor, sticking DHW and primary throttles, broken knobs and leaks everywhere. There's a few other problems but they are rare.

After a DHW demand the boiler will go into anticycling mode and the heating will not fire up again for several minutes. Reseting the boiler will cause the boiler to fire up straightaway in heating mode.

PCB jumpers determine how the gas valve operates...ensure the jumpers are identical to the old board.