oil furnace sooting extensively

[paulmars]

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?

tks,
paul

 

[TBob42]

I had that problem and it turned out to be a faulty pressure regulator. I think it was $70.00 plus the labor. No problems since then. That's the sort of thing i like to leave to professionals. I try not to mess with systems that can cost me more if I poke around in them. NOSHOK is the brand I use for Hyd. pressure gauges.

 

[ponytug]

As @TBob42 suggests, my bet is your pressure regulator, or perhaps a check valve.

You might ask your oil supplier for recommendations.

All the best,

Peter

 

[etpm]

Another reason for excessive smoke can be a restriction in the air supply. I( have had webs inside an air intake cause me problems by restricting air.
Eric

 

[LouNY]

Either too much fuel or not enough air causes the smoke. Nozzle and fuel pressure will effect the amount of fuel.
The air shutter closed down too far or crudded up.
The fire tube or burner head could be corroded or burned out.
I get most of my oil burner parts from;
https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=beckett burners & parts

 

[paulmars]

As soon as i choose a pressure gauge ill ck that and shutoff.

 

[LouNY]

You can also retrofit your burner with a solenoid for a fuel shut off, for a cleaner shutdown. On most burners when it losses the call for heat and shuts down the burner motor it has some slow down time which does result in a bit of fuel supplied at a lower pressure and often no ignition at that point. It is usually just a few drops as the pump restriction and load stops the blower/pump motor fairly quickly.

 

[paulmars]

Because of clearance issues ill need a 4' tube between the pressure guage and pump. How do i get the air out of that?

 

[LouNY]

You could carefully pour oil into the hose after it's hooked up at the pump end. Alternatively you could loosen the gauge a bit carefully with the burner running to bleed the air out.
It doesn't need to be bleed completely a bit of air will act as a pulsation dampener from the pump pulsations.
Or you can get fancy and put a tee at a high point and reduce down to install a bleeder valve,

 

[CH4Ohio]

Nozzles were always the first thing to check on my previous boilers. Good fuel oil technicians are getting very rare! Still lots in use residentially in New England, but here and further south, good luck.

 

[paulmars]

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.

 

[LouNY]

The pressure drop numbers you got look to be a bit low and I don't believe it should have kept dropping.
I'm a bit surprised that you are only running 100PSI, mine runs at 140PSI.

From information that I have;

The A2 VA 7116 model has a unique circuit that exhibits a dependable cut-off, a
high single pipe lift capacity and automatic two pipe purging.
The pump circuit contains a positive displacement involute gear set and two
controlling valves.
APPLICATIONS
- Fuel oil #2 and lighter, not compatible for use with blends higher than 5%
biodiesel.
- One pipe system (two-pipe system possible).
PUMP OPERATING PRINCIPLE
The fuel from the gear set flows across the cone valve causing a pressure
differential sufficient to overcome the spring force of the diaphragm valve. This
causes the diaphragm valve to close and the fuel is then routed to the piston
chamber. When the level of this flow causes the piston chamber pressure to rise
above that of the opposing spring force, the piston opens and flow passes through
the nozzle. The piston spring is adjusted such that a given nozzle pressure can
be maintained while any resulting excess fuel is metered through the seal chamber
and then back to the inlet on single pipe, and the tank on two pipe installation.
Cut-off speed is regulated by adjusting the cone valve to a level which gives the
necessary pressure drop to open the diaphragm valve. This in turn reduces the
piston chamber pressure and the piston shuts off the nozzle.

Improper nozzle cutoff;
Leak at nozzle adaptor ................... Change nozzle and adaptor.
Partially-clogged nozzle strainer ..... Clean strainer or change nozzle.
Tighten intake fittings. Tighten unused intake
port and return plug.
Air leak in intake line .......................
Run burner, stopping and starting unit, until
smoke and after-fire disappears.
Air pocket between cut-off valve
and nozzle ......................................
Strainer cover loose ........................ Tighten four screws on cover.
Filter leaks ...................................... Check face of cover and gasket for damage.
To determine the cause of improper cut-off, insert a pressure gage in the nozzle port of
the fuel unit. After a minute of operation, shut burner down. If the pressure drops from
normal operating pressure and stabilizes, the fuel unit is operating properly and air is
the cause of improper cut-off. If, however, the pressure drops to 0 psi, fuel unit should
be replaced.
NOTE: The A-70 pump circuitry is designed to give a high cut-off of superb quality.
Never use the amount of pressure drop as an indication of the quality or speed of
cut-off.

 

[paulmars]

starting a new thread titled "when to replace oil furnace shutoff solenoid