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oil furnace sooting extensively


Dec 26, 2011
florida usa
In December 2023 I noticed lottsa smoke coming from my furnace. I live in florida, so dont use it too much. I did a smoke test and draft check january 2023 and all was good.

It was still heating house fine.

Many years ago I started doing my own maintenance/tune ups because I could not find anyone in florida to do it right. Even the guy who installed it didnt set it up properly. So, I check smoke and draft at least once a year. I change filter at every take fill. Strainer, nozzle and electrodes (yes I adj them too) every year or two. There are a few other parts that Ive changed as called for in the maintenance manual, that I cant remember right now. I also got the proper specs from the manufactures. One service guy actually came with a later revised spec for a later model and some specs were different. I confirmed with the manufacturer that those specs were wrong for my model year. He also didnt check draft. I can post that letter.

Anyway Im having doubts about my tuning ability, so I again looked for someone qualified. I contacted over 70 HVAC service companies in my and neighboring counties in the past two weeks. I found no one. Many said they could, but when asked how they adj co or stack temp, then didnt know.

Last week I scrubbed out then chamber, heat exchangers, sight tubes, flue, and chimney. Whatta mess! Then I changed the nozzle which was less then 2 years old (it was dripping oil and Ive never seen that before) and even though it looked fine, I changed the pump strainer too.

Im going to order a pressure gauge to hook up permanently to the pump, to check and monitor the pressure which Ive never checked. Suggestions for a good accurate brand?

Any ideas why it was smoking so much?

I've had mixed luck with the service techs but the last one was pretty good. Most of my firing trouble has been related to flow from the tank- either clogged filter- i see yours is new, might be worth a try running with no filter in the can to see if that changes behavior, or low flow from a cold outside tank causing erratic ignition and flameouts. I remedied the last with some heat tape and insulation for the outdoor portion of the run.
I replaced an ancient black oil furnace with a new one about 20 years ago, professional install and annual maintenance, and it also started sooting up over time. This year the maintenance tech suggested I get some power vacuum guys in to clear the flue and chimney. Wow! I should have had that done a decade earlier! An elbow in the flue was about 85% clogged with sintered soot and clinker.
So, I can't swear that was your problem, paulmars1, but since you found a mess in there, it was likely contributing to it!
Once i choose a oil pressure brand ill test the shut off and oil pressure. Because of clearance issues ill need a 4' tube between the pressure guage and pump. How do i get the air out of that?
Some guys say they can set them up by eye (by looking at color of flame, etc.). I bought a digital combustion analyzer to do my own (and smoke tester). It sounds like you're running too rich. Have you tried opening up the air shutter more?
Juck checked pressure and shut off.

Running pressure was proper at 100 lbs

Pump papers say "after shutdown it should be 80% or higher. NOTE: A and B model pumps could theoretically have a cut-off
pressure of less than 80%. The important operation is that it drops to some value and stops."

im type A pump (a2va-7116)

how long should it stop?

Mine dropped immediately to 63, then after 5 minutes on a timer it was 43, then after another 5 minutes it was at 40. Then i removed gauge.
I typically avoid OT threads. But the crap mentioned here is tough to ignore. Couple years ago I installed a new boiler system in my 25,000SF facility. Is the very best quality/efficiency sold. Followed the Carlin burner instructions to the letter for initial settings. Ran fine. My fuel oil distributor offered to have their tech fine tune with a diagnostic analyser. The F'ing idiot filled the furnace room with soot and disabled the system. I contracted with another tech that was no better. Finally I paid thru the nose to have an application engineer travel from the burner factory in Conn to fine tune the system. Now works flawlessly with 87% efficency. The engineer detailed very few techs have formal training in combustion science and are helpless to use a sophisticated analyser. Best I can suggest is to call tech support for your burner manufacture to identify a formally trained person in your area.
Finally I paid thru the nose to have an application engineer travel from the burner factory in Conn to fine tune the system. Best I can suggest is to call tech support for your burner manufacture to identify a formally trained person in your area.
Did that, they dont.

How often do you tune it up and do u hav them come and do the fine tune occasionally?
Did that, they dont.

How often do you tune it up and do u hav them come and do the fine tune occasionally?
I burn about 6000 gallons each heating season, with an annual "tune up." The burner engineer detailed exactly how each adjustment was set. I took clear photographs and made notes if disassembly was required. Tune up consists of removing shroud to thoroughly scrub the exchanger with special wire brushes. Then vacuuming all soot including the combustion chamber. Replace the burner nozzle and inspect the igniter position. Change filter. Inspect flue and chimney for deposits. I plan to purchase an analyser and attend Burner-U. No longer will I have to reply on some bumbling, incompetent moron that insists on charging $120/hr. Suck it Bucko! These training videos are a head start.
I searched for burner-u and all i found was burner you girls basketball.

I still think it can b set by eye, despite all the nay sayers. Ive done that for years, but now im unsure. Maybe all those years I was too rich and sooted up like never before. Smoke was between zero and 1.

Ill start a separate thread "need advice for setting oil burner flame by eye". I know many will say u cant, but maybe a few will give good advice.

I think u just keep increasing flame until it starts getting smaller and that's it. Yea co, co2, oxygen and other levels might be out a bit, but does it really matter? And for all those saying co kills. Well my exhaust goes up the flue.

Ive been using a smoke tester,but since it sooted up, I don't think that will work until all the soot that I couldn't remove gets burned up, which i guess might never happen if my setting aint right.

Stack temperature is critical.
The color and brightness of the flame will tell you a lot. You are looking for a balance between burning clean and efficiency. Higher stack temperature means you are burning cleaner(but less efficient). A dial thermometer in the stack while you are fine tuning is a huge help. Delavan or Monarch nozzles are most service techs favorites. I was a Sears repairman for 27 years.
For regular household heat I don't see much drama in the adjustments... our last tech was pretty good, she did a bunch of measurements etc.. chewed me out for not replacing the filter (old one was a bit full tbh mea culpa) OTOH I had it below 1 on the smoke and stable ignition. OTOH the guy before her was a mess, left the burner so it wouldn't ignite pretty often, sometimes it would take forever to light so lots of wet fuel around. I adjusted the electrodes by eye until I got good ignition and was good.

As a note for the diy adjusters- DO NOT f' around powering for tests with the ignition coil unsecured; don't give into the temptation to lift the xformer off the ignition chamber to look at the spray. That HV spark is wicked. Just turn it off first, then open up to see if fuel is dripping.
I searched for burner-u and all i found was burner you girls basketball.
Here you go: https://carlincombustion.com/class-schedule/

My burner uses 4.5 gallons/hr. Having heavily invested in a new, premium system only an idiot would not take full advantage of its advanced design.

For kicks, search for the forum used by professional, burner techs. Most have graduated the Carlin training classes. The horror stories of hacks filling a home with carbon monoxide and dangerous stack temperatures is eye opening.
Beckett site says could be air leak in line

So I
Replaced oil filter fittings and tank fittings. Bleed the bubbles out as i always do. But then i remembered recently I saw on beckett site says bleed for 15 seconds with no bubbles. Ive never done that long. So, i tried that today. Every time i open the bleed valve it runs w\no bubbles for 13 seconds, then off & on bubbles. Never more then 4 sec w\o bubbles. Continues like that until i close valve to empty my container (20-30 seconds). Then when open again it runs w\o bubbles for 13 seconds and repeats bubbles as above. Did that 7 times w\heater on the whole time (never cycled off). 7th time tried a larger container and after about 45 sec w\bleed open, heater cycled off.

Smoke kept varying from 2 to 5 between each bleed. Why no air bubbles for 13 sec each time? Is this a bad pump?
Visible smoke means your furnace is fubar. doing your own tune ups?
Oh good lord
I have run furnaces for years with never touching a setting. Change an oil filter, whatever.
Find a burner tech, have them get it running right and stop screwing with it.
You will get several thousand hours out of a furnace without touching it, how many years is that in Florida?
I would not change any settings but change parts. New nozzle new electrodes new filter. Clean the soot out
don't play with it.
Like machining without calipers