I have a burner with a Beckett gun that's puzzling me with start up smoke/oder.

I don't believe it's a heat exchanger crack because the smoke is clearly coming out of the damper when the burner fires up.

I wasn't having any problems (that was aware of) but in December I changed the filters and the nozzle and after that I started noticing some smoke on start up. I thought maybe it was a bad nozzle, so I changed it again but it didn't help.

After that I pulled the filters and made sure there was a good seal, not sucking air.

I cleaned the chamber, exchanger tubes, pipes and the bottom of the chimney, mostly a waste of time as they weren't bad at all.

I checked the draft with a manometer and it seems fine while it's running.

I checked all my fittings, changed the electrodes, screen and even swapped in a new coil I had on the shelf.

Some years back I had a dribbling problem that was causing me to melt blast tubes. I installed a Tiger loop at the advice of people here and that solved that problem, so I don't think it's leaking into the chamber.

I did notice how long the motor/pump seemed to be spinning after the flame shut off, and started to think maybe I was pumping oil into the chamber. I installed a fuel stop valve , with a start up delay and that didn't change anything either.

Sooooo.... I'm about out of ideas. I was hoping for suggestions on what else I can check.

 

With late ignition the two most common problems are either electrode adjustment or a weak ignition transformer. The electrode tips should be 5/16" above the nozzle center, 5/32" apart, & 1/16" ahead of the nozzle face.

 

With the manometer you are testing the draft after it has been established. During start up, the spillage can be affected by the natural house pressures which are highest during cold weather. Would you consider your home tight or is the furnace in a room or area with limited combustion air.

I assume this furnace has worked fine in the past, just checking to see if anything else has changed over the past year.

Bud

 

No... this is a house built in the 40's with single pain wood frame windows from the 60's, so I wouldn't think it was too tight.

I assumed the running draft and cold start up were a different matter, but I was hoping the proper draft running meant my chimney wasn't blocked in some way. I DID notice the problem was worse when it was very cold, which made sense to me. But I just got a wife of gas (which is what reminded me to come check the thread) and it's 51º outside at the moment.

Everything was working fine, it went from not doing it, to doing it when I changed the filters and nozzle. But I've re-done all that since then with no change.

The ONLY thing I can think of that I might be different, I thought of the other day and I'm not even 100% sure anymore since it was in December, I MIGHT have taken a Delavan nozzle out and put a Hago nozzle in. (same specs though)

 

Some furnaces are very pickey about their nozzles. I suggest getting a new nozzle, removing the old one, connecting the nozzle assembly (less nozzle) to the small copper line, & flushing 1 safety cycle into a container. That 100# of pump pressure will often flush out small debris in the nozzle assembly you won't even know is there but is enough to partially foul a nozzle.

There is still a strong possibility of a weak ignition transformer.

 

I was hoping it was the coil too, but put on a brand new spare on a few weeks ago with no change. I like to keep new spare parts on hand whenever possible as I've become the guy everyone in the family calls in the middle of the night when there's no heat. Both the nozzle and electrodes have been changed twice since the problem started.

 

Without any kind of combustiion test equipment, specifically a smoke pump, it's hard to say if the problem might be as simple as too much air or not.

At any time when changing the nozzle, or for any reason removing the nozzle assembly, did you loosen the screw on the side of the burner which allows you to move the nozzle assembly forward & back?

 

No I didn't move anything. When I pulled the gun to clean the chamber I double checked it before I put the gun back on and everything was where it should be.

No changes to the air either.


What happens is it fires, and the first blast of "air" causes the damper to open and vent into the basement for a moment. I even changed the pipe setup and the location of the damper slightly (I was never thrilled with the old setup) hoping that would help a little, but it didn't.

If I had some obstruction in the chimney, would i have the proper draft with it running like I do? I was concerned about an obstruction because when I cleaned my fireplace flue, it was loaded with sticks and leaves from squirrels. If the top screen if gone on the fireplace side (which never gets used) I could certainly see it being gone on the burner side. When it finally warms up for good I'll pull the pipe and stick the camera in there to see what I can see.

But even if that's the case... squirrels didn't build a nest in a constantly working chimney and the end of December, exactly the same night I changed the filters and the nozzle.

 

I don't think you have any kind of blockage problem but you MIGHT have a slight down draft until the chimney warms a bit. Are you sure the electrodes are set right?

 

Yes I check the electrodes every time. Once the problem started, I checked them and they looked slightly "warn" so I replaced them. Grasping at straws I swapped in a second set of new ones with no change. There doesn't seem to be any delay or hesitation when it lights. Since adding the delay and the fuel solenoid I'd say it's firing even more... quickly? (Sharply? Immediately?)

 

Without combustion data or being able to see what it's doing, I am reluctant to suggest making any adjustments to the air. Has anyone checked the pressure on the fuel pump? What is the make & model number of the furnace?