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JohnF 01-30-2009 12:45 PM

Help - Problem with Oil Fired Forced Air Furnace
I recently serviced my furnace, including cleaning the line from the oil tank, new oil filter, new nozzle. Along the way, I checked/cleaned the CAD cell, checked the electrodes, made sure that the ignition system is working (igniter unit went bad and had to replace).

Unit is the newish Beckett (the one that has the "push on" clips to the electrodes and the blue window in the back to see ignition.

This was about a month ago. In the last week I have had a problem where the burner does not want to ignite when there is a call for heat, and of course, switches itself off. When I push the reset, it comes on, and I can see that the electrodes are doing their thing through the window. Interestingly, if I open the window, and try again, the furnace will most often start, then be good for a while.

Only thing that I can think of is that I have some sort of air problem, that opening the window overcomes - but I am no expert.

Can one of you experts tell me what to look for?


Bondo 01-30-2009 01:09 PM


How was the electrode alignment,..??

JohnF 01-30-2009 02:00 PM

Checked Electrodes
I checked the electrodes - they looked good, and I used some real fine steel wool really just to polish them up. I set the spacing per the beckett manual, used a caliper, and I think I got them very close to spec.

As i mentioned, I can see the sparking when the burner is trying to ignite, so I (think) I am close here (I guess if they were misaligned from the spray that would be a problem, but I really dont think so). If you feel that this is a likely problem I will pull out the assembly and re-check.


Bondo 01-30-2009 02:39 PM

Ayuh,.. I'm not a Burner Tech, John,...

I have been messing with them for 35 years, though...
I'm just throwing out Ideas,...

I doubt it's an Air adjustment problem,...
And, Messing with it, Without a Meter, is a Crap Shoot at Best...

JohnF 01-30-2009 09:01 PM

Well, that is about 34years 11 months longer than I - I appreciate any thoughts and help!!


Mainah 01-31-2009 06:46 AM

when you put the nozzle assembly back in did you push it all the way forward until it stopped?

what did you put in for a nozzle?
might be starting to plug up on you-
flush the oil line again until you get a nice clean oil flow, flush the jet line that goes to the nozzle adaptor too.
then change the nozzle and see what that does for you-

what's the model of the furnace?
size nozzle?
adaptor pin# ?
air setting-?

beenthere 01-31-2009 06:51 AM

Did you change the combustion air adjustment when you changed cleaned the burner.

A combustion test woiuld tell you if it was a combustion air problem.

JohnF 01-31-2009 03:11 PM

Back home, so I can provide a little more in the way of details. I got home last night, and, again the control was in the 2 second flash (Recycle mode). I hit the red button the motor started up. Burner did not ignite immediately, so again I opened the rear access door and it started up (with some smoke out the back). I am assuming that is because the access door was open.

Burner is a Beckett AFII -85 with 100 PSI cleancut pump
Head is FB0
Nozzle is .5 GPH-80A and the one I installed was brand-new.
Furnace is a Lennox O23-70

Mainah - I am not sure what an adapter pin is. The air-dial setting is at 3.

Originally (say 3-4 weeks ago) when I replaced the fuel filter and nozzle, I did completely flush the line from the tank to the filter, and from the filter to the fuel pump - blew them out with air. I also cleaned the line from the pump to the nozzle and was definitely getting air flow through there.

When I did all of this, I did not mess with the air dial setting at all. I also did not adjust the escutcheon plate, so the nozzle has to be in there all the way.

If you guys think it is worth it, I can go thru the whole routine again from oil tank to nozzle, but if not, I would rather not tinker with it again...:)


Bondo 01-31-2009 03:53 PM


Here's My WAGuess,....

Generally speaking, what you did to the Fuel Lines was maybe the Wrong thing to do....
Blowin' em out with Air might have dislodged some junk that was quite happy just laying where it was...

Just changing out the Filter,+ rag cleaning it's housing is All I ever do,... Unless I'm chasing a known blockage....

Any minute bits of sediments,+ whatnot would take centuries to cause any real problems,... As long as you're buying clean fuel...

I drop in a Qt. of a Bio-cide fuel treatment once a year, usually in the fall,+ done by my delivery guy, so it mixes well....
A month or so later,... I go down,+ do the usual service job,... General Cleaning, inspecting,+ filters, nozzle, etc...
If the filter isn't full of Black Sludge,.. My tank is healthy,+ Alge hasn't infested it...

I think I would open it back up, change the filter,+ nozzle again,+ Try it....

1 last crazy idea,... Did you get the igniters far enough forward,..??

beenthere 01-31-2009 04:01 PM

If it was air in the oil line. Then he would have to bleed it, for it to pump oil to the nozzle again.

Could be the new nozzle is bad.
Transformer is weak.
May have moved air adjustment unknowingly.
Ignitor not in proper position.

And several other things.

Bondo 01-31-2009 04:07 PM


If it was air in the oil line. Then he would have to bleed it, for it to pump oil to the nozzle again.
Ayuh,.. Agreed....

Just pointing out that BLOWING the lines out would/ could dislodge enough Junk to plug a tiny 1/2gal. nozzle...

Mainah 01-31-2009 04:38 PM

the pin is how the z-dimension is set for you- it is a changable part that sits atop of the assembly, when re-installing the assembly you push it all the way forward until the pin hits the stop- then tighten the plate and attach the thumb nut-

if this is not all the way forward it could change the air flow and make it hard to start-

beenthere 01-31-2009 05:08 PM


Originally Posted by Bondo (Post 222594)
Ayuh,.. Agreed....

Just pointing out that BLOWING the lines out would/ could dislodge enough Junk to plug a tiny 1/2gal. nozzle...

Sorry, misunderstood you.

JohnF 01-31-2009 09:04 PM

Ok, some good suggestions there...

Tomorrow AM I will pull the assembly, check everything again, and try putting in the old nozzle. There was nothing wrong when I was running it before, so perhaps the new one has an issue. Will also check all the dimensions on the electrodes, especially to check if they are far enough forward.

Is there any way to unwittingly set the air adjustment wrong other than moving the air-dial? I know that I never touched that, but if there is something else that I might have moved, that is a possibility.

I never noticed any sort of z-dimension adjustment for the assembly, so when I pull it out I will look again - guess it is possible that I might have unwittingly done something there...

Guys, really appreciate the noodling on this, I have been banging my head against the wall on this and it is starting to get mushy...


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