Worcester Danesmoor 15/19 oil boiler problem

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I am getting a lockout on my Danesmoor 15/19. It fires just fine and continues until the ignition stops and then the flame dies. It looks as though the controller is shutting off the pump with the ignition. This seemed to be a very obvious photo cell problem to me but I have replaced it with a new one and in any case both the new and old cells have pretty much the same resistance readings (covered and uncovered) so I can't see that being the problem.

I have reset the thermostat on the panel (it did need to be reset) but that made no difference.

I have done quite a few things with this boiler over the last few months; new seals, new motor bearings, new nozzle and electrodes, new transformer. These all needed to be replaced at different times but this latest one has me stumped except for the idea that it is the control box. But I don't want to waste money on this unless I am sure it needs replacing as the whole boiler will be changed in the coming months.

Can anyone help?
 
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Ok, so it's not the control box - I have tried a new one and the results are exactly the same. I did get it working for a while last night, though not because of the new control box. Had a look at the solenoid valve on the oil pump and it seems to work ok - internal spring operational etc. I don;t know why it suddenly started working but it followed my taking the pump off and also returning the solenoid valve wiring back to how it should be.

I rewired the valve directly off the motor terminal. The reason I did this was because the valve terminal was giving about 40v and the coil itself has a rating of 220/240v so I figured it would be ok to take it off the motor terminal at 220/240v. Sure enough when I do this it seems to make more of a 'clunk' so it sounds more like it is operating the valve.

Anyway, it did not fix the problem when I did this but when I put the pump back on and put the proper wiring back it suddenly started working. Coincidence? I think it might be.

It did get me thinking that it might be the pump at fault though as the problem manifests itself in exactly the same way regardless of whether the solenoid coil is in place or not. What I don't understand about this where the fuel comes from for the initial firing when the solenoid valve is closed. I had imagined that the valve needs to be open for any fuel to get to the burner but the way it looks is that there is enough fuel for the initial burn with the valve closed after which the control box opens the valve.

Can anyone tell me if I am correct in what I have said above? Do I need a new pump?
 
Try a new coil 1st, it sounds as if it's failing to open (quite a common fault) I'd also advise wiring it back to it's own terminal you don't want it throwing oil into the combustion chamber if the spark ever goes intermittent.
 
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There can't be any flow from the nozzle until the solenoid valve opens and allows the pump to force oil out.
Solenoids contain a coil and failed ones have a habit of working when cool and then due to heat go open circuit, which leads to lockout.
Regarding the pump a couple of questions you should ask yourself.
How old is the pump?
Does it have to draw oil from a tank below the level of the burner.
The best action to take is measure the pressure.
Mine measured 20lbs per sq in should have been 100psi and I could not get any increase by adjustment.
 
I am amazed at the cavalier attitude that people have with regard to oil burners.
Wiring up the solenoid to the motor terminal means you could be injecting oil spray into the boiler for up to 20secs before energising ignition. A few weeks ago we had a posting on here where a similar thing happened and the resultant explosion deformed all the baffles and the access cover.
you are lucky that you have not maimed yourself or burnt your house down.
 
Thanks to all for your replies. It is a gravity fed system. I checked the pump pressure earlier in the year and set it to the correct pressure and it has not been used since. It was not far out anyway. I am not sure how old the pump is but I did take it apart a while back and the drive pin was worn, and yes I am aware that I may have created a problem by taking it apart but it does seem to still work consistently.

Is it possible to buy the solenoid separately? I thought Danfoss only sold the pump as a complete part.

Oilman: You make a fair point. I fully expected to burned on here (pun intended) for admitting I rewired the terminals. Hopefully, I am not quite as cavalier as it might seem though, as the Danfoss documentation does state the motor should to go onto the valve terminal in the absence of the solenoid and that is must be wired in parallel if the solenoid is present. If this was not suggested or I had thought the ignition was delayed then I certainly would not have rewired it and I definitely would not recommend anyone else should take my lead.

I did correct the wiring immediately after having tried the change.

Is it possible to buy
 
Just rereading the replies: I misread 'coil' as 'valve' earlier. A dodgy coil is something I had not thought about before. But I still don't get why it initially fires up every single time and then only after the initial sequence (20 sec) does the flame go out at the same time as the ignition. I don't think it can be due to the coil heating up as it does not go long enough for this to be a factor.

What could be up with the nozzle/burner such that the flame can't sustain itself without the ignition? I have rechecked the nozzle position and spark terminal gap etc. It all seems ok based on the documentation I have.
 
I bet the flame is igniting the moment the Burner & Ignition start, and BEFORE the Solenoid opens, this would result in "FALSE LIGHT" aND UNDER THESE CONDITIONS THE BURNER WILL SIMPLY LOCK OUT AT THE END OF THE SAFETY TIME - Which is exactly what the OP describes
Replace the solenoid stem (the part that the coil fits on to) that will fix it!! :rolleyes:
 
Thanks Mandate and Boilerman2. I have already tested the coil in situ by placing a screwdriver in the centre to see if it exerts any force on it. I didn't feel any which is why I tried the rewire to mains voltage. What I still don't understand about this is why both control boxes (old and new) only provide about 40v on the coil when it has a rating of 220/240v stamped on it.

All that aside, I think Boilerman2 has it. I'm not really familiar with the concept of false light but my guess is that the valve is not ever closing properly, the photocell 'thinks' it is seeing false light from the burner starting too early and shuts down following the ignition cycle.

I'll ask my previous question again - can I buy a solenoid stem separate from the pump?

Thanks everyone :)
 
Ok, scrub that last question - just found a solenoid stem. Can't believe how pricey they are though. Half the price of the entire pump! Cheers
 
The stem is expensive BUT a lot easier than changing the pump - no oil pressure to reset etc

I've changed one today after finding 3" of oil in the bottom of a boiler!! :LOL:
 
Been offline for a few days. My phone line went down and BT took their time about it.

I have now purchased and fitted the new stem and sure enough, it fixed the problem straight off and works perfectly now. Big thanks to Boilerman2 for that.

I like your logic BM2 as having to reset the pressure was basically the reason I went for the stem alone. I don't have a pressure meter so the stem made for a quicker and cheaper solution. Now I am just hoping the pump holds out until I get the boiler changed over...

Thanks again to all.
 

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