Boiler lockout when cold

[Julian Cooke]

After 5 years , my Suprima 70 is doing the 'lockout' . I have had the PCB replaced twice recently as well as the overheat thermostat but still same. It's been suggested I should have the pump over-run wired in, but it has been OK without it for 5 years and it only 'locks out' when cold - never when heating is on.
Could pump over run cure it? I can't comprehend why it should!

Julian

 

[oilman]

If it locks out when cold, you are right to suspect the benefits of adding a pump over-run. Pump over-run is to take the residual heat away from the combustion chamber just after combustion stops, to stop the local temperature getting too high.

The problem would be the fuel/air ratio if it was oil, but with the relatively sophisticated electronics in gas boilers, it may be connection problems. You'll need some help from the gas boys, as I know nothing about gas boilers. (Ignorance is bliss )

 

[IanDB]

I had this problem with a new LPG boiler when first installed and as Oilman says it was to do with the gas/air mixture. After it was set up correctly it never happened again. Suggest you get this checked.