Worcester Bosch Danesmoor 20/25 - locking out

[anotherbassman]

My boiler has just started locking out and I am hoping for some advice.

Burner is Electro Oil Inter B11C with conventional flue, oil tank above boiler, single line to Danfoss BFP 11 pump. The boiler has run from new faultlessly for 5 years. System is Honeywell S plan, sealed.

I have cleaned the burner including fan inlet, shut off valve and photocell, the filter inside the pump and the boiler/baffles etc. Everything looks as it should, fuel was clean inside the pump and nozzle and the motor turns easily by hand.

Problem is the boiler fires up as per normal and then locks out after about a minute. Fuel is igniting no problem and it sounds sweet while running. Central heating pump is running fine - it all operates just as it has done for years - apart from the lock out!

I have spent the evening looking through old posts on the forum and it seems a likely candidate is the oil pump solenoid coil part no 071N0010? Also it may be the photocell? These parts are not so expensive so I thought I would change them and see if it fixes the problem. Does this sound like a good plan? Is there anything else I could try?

The nozzle is the original - its a 0.75 X 80EH - should I change this as well?

Any advice much appreciated.
Jon

 

[holty]

Does this sound like a good plan?

basically no. unless you have the gear to set up an oil boiler and the knowledge on how to use it. when you say lockout. which lockout. the burner or the boiler. both very different.

 

[anotherbassman]

Thanks for replying. The burner is locking out.

 

[oilman]

How long does it run for before it locks out?

 

[anotherbassman]

About a minute.

 

[oilman]

Could be fuel starvation. You need to check the oil filters are clean. It could be a dirty photocell, or could be the coil. If you have a meter, check the resistance of the coil immidiately after it locks out to see if it is open circuit.

 

[anotherbassman]

Thanks oilman - will check the coil resistance. All oil filters are clean (external, oil pump and nozzle) - just cleaned them (although they weren't dirty). Photocell was clean as well but I cleaned it anyway.

 

[anotherbassman]

Checked resistance this morning when cold = 2076 ohms

Ran boiler to lockout (about 4 minutes) resistance = open circuit

After about 5 minutes resistance = 2096

Picking up a new coil now.

Thanks oilman

 

[anotherbassman]

Boiler now running fine with new coil - thanks again