Boiler only fires with casing off!

[Hobo128]

Went to a job the other day, customers boiler had stopped working. i took the casing (combustion casing off) and it lit up. I put the case back on and it stayed lit. When I turned it off and back on it didn't light Dhw or Central heating. I checked the air pressure that was fine and checked the flue for blockages and all was fine.

Boiler is Sime Ecofort plus 30 HE

Any idea's.

 

[zeebeedee]

It's an air supply problem, usually aps or a blockage around it. Ie on the hose or the Venturi on the flue. Split aps hose etc etc.

 

[kris]

Zeb bang on defo an air supply issue. As itd gettin plenty air with casing off. Like already said check flue, hoses, venturi. + air pressure sw.

 

[mfgs]

As has been said, air supply. Check flue, APS and hoses, fan venturi etc.

 

[Ermintrude]

Check your training . Sime - any fault died with axe. It's air supply as evacuation would cause excessive heat and o/h lock down. Check Venturi tubes in the flue not all pooped

 

[smtplumbing]

Venturi sime and vokeras are bad for it