Grant 50/90 Riello RDB not working

[MJPH]

I have a problem with my Grant 50/90 oil boiler and Riello RDB burner.( located in garden in cabin pac ) Nothing is happening at the boiler !! The timeclock is on, the pump is running, 0.5 - 1.0 bar system pressure, room stat calling for heat and motorised valve open for heating. Boiler is not locked out, overheat stat has not tripped out but nothing happening ? Any ideas ?

 

[tipintim]

Check for power at boiler.
Overheat stat reset. Press red button.

 

[MJPH]

Hi tipintim, power at the boiler and overheat stat has not tripped !

 

[tipintim]

Frost stat?
Something is not calling for heat. Check wireing.

 

[MJPH]

No frost stat fitted but I was wondering if it could be the actual boiler stat ? Would this always lock out if there was a fault or could it just stop calling for heat ??

 

[Best]

If the burner has locked out there will be a light on the lockout button on burner. If this is not the case there may be a fault in the thermostats. It is possible to have a faulty control box on burner, that shows no red light, but this is rare. Have the power to burner checked first.

 

[Best]

No frost stat fitted but I was wondering if it could be the actual boiler stat ? Would this always lock out if there was a fault or could it just stop calling for heat ??

The main, control stat if failed, would let the boiler overheat & then the limit stat would limit the temp by turning off permanately. It is only resettable manually by the limit reset button. ( some limit stats are automatic types, that reset when temp lowers, but normally not)

 

[Gray0689]

On your stat at boiler there will be a small plastic screw cover once taken off there is a small button try and press it in

 

[MJPH]

Hi Gray0689 Please see from original post : Nothing is happening at the boiler !! The timeclock is on, the pump is running, 0.5 - 1.0 bar system pressure, room stat calling for heat and motorised valve open for heating. Boiler is not locked out, overheat stat has not tripped out but nothing happening ? I think it must be a control issue as it seems like the boiler is not being called for heat !!!

 

[tamz]

Hit the test switch and see what happens. If nothing there is no permanent live going to the boiler.

 

[kimbo]

Can you hear a slight humming or buzzing noise from the boiler, check to see if you have a live supply to the burner.Something may have seized such as the pump or motor or even the capacitor might not be generating enough power to start the motor, this is usually accompanied by a buzzing noise.

 

[Best]

As the water pump is running, the burner should be getting power. Check limit stat as has been said by a lot of us, & if power is getting to burner, then control box is likely if no lockout.

 

[MJPH]

Hi Tamz, what is the "test switch" to which you refer ?

 

[MJPH]

will try that thanks