Grants central heating and water gradually becomes cooler

[granted]

I live in a rural area and have had 3 ch engineers trying to fix my Grants combi 90 mk II problems with no success so tried myself with advice. I renewed the expansion vessel (fixed pressure loss).

Advised to and renewed the control box as ch/water came on intermittently but when heating ch/water the heat gradually became cooler and the motor continued running as temp failed to reach thermostat settings. Renewing the control box has not fixed it. Any ideas?

 

[Boilerman2]

Try replacing the Photocell - this is a common fault
the burner fan runs, but due to faulty photocell, the burner does not actually fire, resulting in loss of temperature, eventually the burner may fire up and this then re-heats the water.

This is the likely problem from your description.

 

[granted]

Thanks for your advice Boilerman 2, will do that.

 

[granted]

Boilerman 2 your advice worked, I renewed the photocell today and all's well.
Thanks a lot

 

[dcawkwell]

Try replacing the Photocell - this is a common fault
the burner fan runs, but due to faulty photocell, the burner does not actually fire, resulting in loss of temperature, eventually the burner may fire up and this then re-heats the water.

This is the likely problem from your description.

Strange I would have expected the burner to lockout with a faulty photocell.

 

[Boilerman2]

Then you clearly know NOTHING about Riello Burners!!
they will simply purge if the photocell is not detected by the control box during safety stage the PE cell is faulty 99% of the time where the burner permanently pre purges without lighting

 

[Boilerman2]

Granted - Very pleased to help

(I was Grants Technical Support field Engineer after all!)