Worcester Bosch Heatslave 15/19 lockout and not firing

[happyjack]

Hi
Just after some advice trying to work out what the sequence is for the boiler to fire. I have just under 1 bar of pressure on the system so that should be fine. It had cut out yesterday on over temperature so have reset it and now it is cutting out on lockout. I have plenty of oil up as far as the pump. When I reset lockout the motor fan pump kick in for about 15 seconds but there is no click or attempt to fire but it then goes to lockout. Does the solenoid open the same time as it tries to fire. I'm just trying to work out if the click is the solenoid opening or the sound of the HT spark firing.
Would appreciate any ideas to next line of attack

 

[Burnerman]

Here's the start up sequence.....motor starts (fan on the same drive, actually the back of the motor) and runs for about 6 sec, ignition spark at the same time. Then, oil pump solenoid opens, the burner should light and the flame establishes, ignition stops.
The problem initially could be the solenoid coil (common) or the photocell, thinking the flame is actually there when it isn't.
John

 

[happyjack]

Thanks John
I will check in the morning but when I took the burner out it seemed dry and no sign of fuel so will check solenoid coil first and go from there.
Cheers

 

[happyjack]

I've stripped the burner again. The solenoid is definitely clicking and opening. Went through a start sequence, fan/pump, solenoid click, but then into lockout after a few seconds then stop. Took burner out and there is fuel wet around the nozzle so I imagine there's no spark. If the photocell was faulty I would think it would fire then cut out but it doesn't look as if it fired and didn't sound like it fired. Does anyone think it may be the HT transformer? I measured the resistance on the secondary across the two electrodes and had a reading but on the primary side it was higher than my meter (above 2 KOhms.) so it may be open circuit. Does anyone know what sort of primary resistance there should be on the transformer by any chance.
Thanks
Mike

 

[Burnerman]

A diy spark test.....pop the burner out, pull out the solenoid coil connection and switch on - you should see a spark right at the electrodes.
Carefully does it!
Transformers do fail, naturally enough.
John

 

[happyjack]

Spot on there John, Transformers do fail....... mine has failed.

Took burner out and fired up without solenoid connected and no sparking. I then remembered I had an old burner that seized up with water in 2002 in the shed and result, it's the same Danfoss EBI transformer. Just swapped it over and fired it up on the floor and it's sparking nicely. Burner is back in and running. Time for a full service I think.

Thanks for all the info John!!