Oil boiler oddity

[cornishbloke]

First post so hopefully I give all the info needed.

We have a strange annoying niggle with our oil boiler that I hope someone might be able to point me in the right direction to resolve.

The issue is that the boiler goes into lockout requiring the red button on the burner to be pressed to reset after the boiler has been on for a period of time with the case closed. If the front of the case is removed the system works faultlessly (currently two months or more with the case open) it has never locked out with the case open. With the case closed it will fire up on its own from cold (provided its not already locked out) but then after a period of time locks out. I had a OFTEC approved engineer look at it who gave it a service and checked the flu reading etc, apparently everything appears within spec. I know its an old boiler and system but it gets the job done and I am loathed to replace it but I would feel much better if the case was closed and it running as it should.

The system is a classic Boulter Economy 50/70 system boiler (Riellio 40 burner) located in the garage, all rads are getting hot and it heats up the hot water nice and quickly.

Any ideas appreciated as this is the kind of thing that drives me bonkers.

 

[Jadele]

Apparently there is a light sensor onthe boiler that detects ignition. Perhaps that is failing and with the cover off external light is supplying enough light to keep the boiler from locking out. No idea really but just a thought.

 

[oilhead]

This boiler is a case sealed balanced flue model. When the case is fitted, it draws its combustion air from outside through the flue duct. Your problem is caused by the leakage of flue products either from the baffle access cover seal, a leaking flue pipe joint within the duct, or a leaking burner gasket. Testing with a flue analyser specifically around these areas will locate the problem.

 

[Burnerman]

As above.....with no flue interference whatsoever (as I found recently concerning a home made flue cowl.)
John

 

[cornishbloke]

This boiler is a case sealed balanced flue model. When the case is fitted, it draws its combustion air from outside through the flue duct. Your problem is caused by the leakage of flue products either from the baffle access cover seal, a leaking flue pipe joint within the duct, or a leaking burner gasket. Testing with a flue analyser specifically around these areas will locate the problem.

Thanks for the detailed reply oilhead, I had read previously about the balanced flue aspect and this makes total sense, I am guessing some of the flue gas is being sucked back into the intake and causing it to cut out due to lack of o2? Would there be physical evidence as the where the leak was on the flue (dirt buildup), its a very short flue which goes straight out the back wall of the garage?

Being as the boiler is in the garage and not in an inhabited part of the property I assume it is it safe to run as is with the case open until I can find someone to have a look at it? I think a different engineer this time though as the last one didn't even suggest this as a possibility.

 

[cornishbloke]

As above.....with no flue interference whatsoever (as I found recently concerning a home made flue cowl.)
John

no diy fixes attempted other than opening the case.. and checking that the snails hadnt setup home in the wrong spot round the back of the garage!

 

[oilhead]

You may see some scorching round the burner gasket or top cover. My bet would be the top cover seal. A metre or so of 13mm rope would cure this. In a garage, running it open should not be a problem as long as you are aware, until you can get it sorted.

 

[cornishbloke]

You may see some scorching round the burner gasket or top cover. My bet would be the top cover seal. A metre or so of 13mm rope would cure this. In a garage, running it open should not be a problem as long as you are aware, until you can get it sorted.

Many thanks for the help, much appreciated.

Ian