Grant Oil Boiler Firing, stopping firing etc?

[jimk280]

I serviced an oil boiler the other day that hadn't been done for over 6 years! When trying to take an Analyser reading I found that the burner seemed to be firing for 20 secs then stopping for about 10, firing then stopping continually through the same cycle although the fan was continually running? The boiler is a grant multipass 50/70 utilising a balanced flue. Anybody got any ideas of the possible cause?

cheers Jim

[paulgreen2504]

Hi

I am experiencing a very similiar issue with a grant Vortex 26kw external condensing combi oil boiler which is only 18 months old and this only happens at roughly 05:30am when it is due to come on. Same conditions - fires up, stops, the fan is continueally running.

When the customer gets up. They turn off the system, waits 5 mins, turns it on again and this time it works fine.

Does anyone have any ideas?
regards


Paul

[tipper]

Check for water in the oil or more likely icing of the water in the oil particularly at the tank outlet valve/filter which blocks off the oil supply. I know what you are thinking that oil doesn't freeze but the water in the oil does!

Also may be the sludging of the oil due to the oil bacteria/bug when it also blocks the outlet filter.

[paulgreen2504]

Thats a very good point. I should know this, given I fly planes and the first thing we check for is water in the fuel.

Thanks

Paul