Worcester bosch heatslave 12/14 oil pump pressure problem

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Hi all , I'm hoping that someone could shed some light on a frustrating problem I have with the oil pump on a Worcester bosch heatslave 12/14 , it seems there some reason that on initial fire up from lockout, the start up sequence dose not operate in the correct order ?,
If I'm right believing that the sequence should be
Fan motor
Spark
Ignition
Photo cell
Selanoid

But my sequence is
fan motor
Fire up
Lockout
No click from selanoid

I've checked everything and replaced nozzle , bled the air from the pump with gauge and set pressure at 100 psi , stripped the pump completely, fitted new seal kit to the pump the only way I can get the burner to fire up and keep running is

Turn oil pressure way down to 20 psi until the selanoid clicks then wack the pressure back up a good half of turn and the burner runs sweet

If anybody has any suggestions I'd love some advice please, I'm at a loss with it now
 
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The start up sequence is......
Purge for around 8 sec - motor spins, spark occurs
After the purge, solenoid opens the valve and oil spray ignites
Photocell sees light and keeps the oil flowing
Ignition spark stops.
I’m wondering what you’ve done to the pump - if it can maintain 100 psi and more it should be ok.
You haven’t commented on the position of the electrodes though......the narrowed part should be around 3mm from the end of the nozzle. The oil spray ignites because the spark is blown into the spray - often the electrodes are set too far out.
Reducing the oil pressure to 20 psi is an unusual thing to do!
John
 
Hi John thanks for your reply
In regards the electrodes I have set them to the handbook 2.5mm spark gap , set 2mm away from the end of the nozzle and 10mm away from center of the nozzle

I can crank the oil pressure right up on the pump and it doesn't struggle to run at 150 psi

The problem is that it fires up instantly without the purge which is pretty bizarre
 
Very strange!
The purge interval is determined by the control box...is it the TF 830 ? Something wrong if the purge cycle isn’t there.
I do keep a spare, but they are one of the best controllers.
Your electrode settings sound to be just fine, and if the pump can deliver 150 psi there can’t be much wrong with that.
John
 
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Yes I actually have two control boxes Honeywell DKO 970 & Bentone TF 832.3 which both work fine but just to make sure I bought a new on the other day to try and no difference whatsoever so took it back

Also replaced the selanoid and again I have another and two selanoid plungers
New nozzle ,fan motor is very recent
I'm just out of ideas now lol
 
I guess this is a B9A burner?
Have you checked the flue ways for any obstruction, and is your boiler room sealed - i.e the burner is in it's own steel box?
John :)
 
If the burner fires before the control box initiates the solenoid then it will lock out as a false flame. It would appear that the solenoid valve is passing as when you turn pressure right down it operates correctly. Clean out the solenoid port and if it still fails, replace the pump.
 
I think I have found the problem and it was also backed up by Worcester bosch service technician who I called this morning, I had a suspicion that it could be the mechanical che k valve located in the Nozzle assembly tube , I explained my problem to him and I also suggested that the check valve may be the problem , because there shouldn't be oil in the nozzle while the fan first starts running and not before the selanoid opens the oil supply , because there's oil in the nozzle tube it fires up straight away then the photo cell sees it and puts it into lockout , this is why if I turn the oil pressure right down before the selanoid click the burner doesn't fire, but once it clicks and I wack the oil pressure if it fires and works as it should

So I've ordered a check valve as they don't have any in stock in Cornwall, it will be here tomorrow morning , will keep you posted
Many thanks for your and burnerman help and suggestions it is much appreciated
 
Finally got to the bottom of the problem , turns out it's the small Oring seal on the bottom of the Selanoid plunger all sorted now back up and running , thanks again both of you (Burnerman & Oilhead) for your help muchly appreciated
20250201_153220.jpg
 

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