Worcester Bosch Boiler keeps getting air in pump

[fenderblast]

Hi,

I've got a Worcester Bosch Danesmoor WM 12/19 oil boiler that keeps going into lockout due to air in the oil pump.
It'll run fine until the thermostat turns it off but then it won't restart and goes into lockout. I've been outside far more times than I care to count to bleed air out of the bleed port on the manifold, but the problem persists! I've had the engineers who installed the boiler many years ago and who have always serviced it out twice in the last 2 days to look at it, and they report back that they've checked all the fittings are tight and the non-return valve is working correctly. They'll bleed the air out of the pump and leave it running, but it's gone into lockout by the time I get home. Frustrating does not even come close.

If anyone has heard of this problem before, or has any ideas on what I could/should be checking, it'd be very much appreciated!

Cheers,
Chris

 

[dcawkwell]

Since this is a wall mounted boiler.

If wall mounted and single pipe system with a non return valve then
replacing the non return valve would be the first step. A leak in the piping is also very possible. Ensure there are no joints in the piping from the tank or those there are do not have an air leak. Pressure test the oil line.
Or swap to a two pipe system if possible.

A tiger loop also fixes problems like this.

 

[fenderblast]

Since this is a wall mounted boiler.

If wall mounted and single pipe system with a non return valve then
replacing the non return valve would be the first step. A leak in the piping is also very possible. Ensure there are no joints in the piping from the tank or those there are do not have an air leak. Pressure test the oil line.
Or swap to a two pipe system if possible.

A tiger loop also fixes problems like this.

Thanks for the advice dcawkwell. It is a singke pipe system, and the installation manual for the boiler says it should have a twin pipe set up. Why it wasn't installed that way I have no idea. Hopefully, the boiler will be replaced in a years time when we have an extension built, so I just need it to work for that long for minimum expense.
After giving it one last really thorough bleed through (and it failing again), I've called the engineers back in. They've suggested a tiger loop as well, so one is being fitted on thursday. fingers crossed it'll work!