Posted on 02/26/2016 4:36:04 PM PST by Ghost of SVR4
G'evening folks...Just a bit of HOWTO this evening if anyone is inclined.. My furnace started acting up on me two days ago. It would run for about 90 seconds then cut out; blower still ran, then rinse and repeat. I did quite a bit of the googles and came to find it was either a thermostat (main) or a limit switch. Welp, replaced the thermostat (I'll post later in this thread about those interesting findings) and same results. Had to order the L150-40F limit switch because no store around me would sell to the "general public" and the home stores did not carry them. Soooo..Had one flown in from another state. Part? 9 bucks. Shipping? 30. (rolls eyes). Okay, so, new part in. Still the same results.. UGH...its cold here and I have to get this pup fixed.
Turns out, my filtrete filter had bad markings on it. The "airflow" arrow (which I have followed for 15+ years) I believe was marked wrong. I pulled the filter and my furnace came alive and went back to doing its job. I replaced the filter (which was only 4 months old) and checked my input airways the best I could.
So, the furnace is humming along, but when she shuts off, after about 45 seconds it emits white smoke. Not enough to kill ya or set off a fire alarm (I have one in that room as I type). I pulled the the electrodes and nozzle assembly and I admit, a bit gunky so I replaced the nozzle and cleaned things up a bit (note, I did not have to re-gap the electrodes). Got everything back together and still some white smoke comes out after the burner is off (around 45 seconds) and the blower is still operating. It lasts for a bout 45 seconds while the blower is still doing its thing and once that is done. POOF, it all stops.
I'm wondering if there is some residue oil just cooking off after a couple days of cycling so much, or? Any ideas?
I do not believe my home is going to burn down. Yes, yes, I know, call a professional and I probably will since I want to sell the place in six months and want everything tip top for the next owner.
This is just eating at me because I cannot figure it out and these furnaces are not extremely complicated.
Beckett Oil pump AFG, 70/70-A nozzle (replaced) calibrated, Generic burner.. Type II fuel oil.
Anyone seen this before??
When the flames go off do they go off like a switch or do they Peter off slowly?
Sign a three year contract with a reputable AC/Heating firm to keep your system running smoothly.
But then you probably thought about that before you posted this bit of nonsense.
How’s your other appliances working? Can’t wait to hear about the next crisis.
Contaminated fuel would be my guess too.
Just like with a car white smoke may indicate water getting into the combustion.
Maybe a leaking recirculating water pipe inside the furnace...
That would be about a 1/4 million dollar problem after the EPA got done with him.
Condensation?
It needs to be cleaned. The heat exchanger is choked up.
Do you have to push the reset each time after it turns off?
If so then I would be very suspicious that flue or chimney might be plugged or restricted. If it were then it would cause white smoke to build up in the fire chamber which would leak out the inspection door. It would also obstruct the view of the flame reaching the electric eye and cause it to shut down on safety.
Oil burners are usually very easy to diagnose in person if you know the symptoms. But everyone of those symptoms are important for proper diagnosis.
Does the flame light immediately after when the burner starts?
Does the flame look good in the first couple of seconds?
Furnaces help to destroy the planet, you know.
I was thinking about a leak in the tank.
If you don’t have cracks in the supply lines between the tank and the burner, and the burner works for the correct duration (what you know as a typical duty cycle), then it is likely the blower overheating.
Can you tell where the smoke is coming from exactly? What does it smell like?
Hire a professional who knows what the heck they’re doing..........Furnaces are nothing to screw around with.
WE ARE OUT OF BATTERIES. LOOKS LIKE WE ARE GOING TO HAVE TO GO BACK TO DOING EVERYTHING BY HAND.
Here’s someone (from 2007) who appears to have had the same or similar problem. Go to the link to check the responses. I haven’t yet.
“Excuse me if I use the wrong terminology...but I have a fuel-oil furnace that white smoke appears through the burner after the burner shuts off and the blower is still running, after about 45 seconds...white smoke starts to come out of these small holes on the burner and fill the basement with white smoke and smell like fuel. ...”
What you describe may be what the fire service refers to as a “white ghost”...
Article from Fire Engineering on the subject of oil furnaces...
May help you diagnose possible problems...
Be careful...That white cloud is fuel/air mix and somewhere within lies the flammable range...Possible Ka-blooey situation!
I was going to write, “Congratulations, you just ELECTED a pope” since you can’t vote for yourself.
Hey, I just did. Never mind!
“I don’t have the actual “light sensor—
I don’t know how that could be as it would turn your furnace into a potential bomb. That sensor is a major safety component.
The electric eye or light sensor as you call it is located under the ignition transformer on top of the burner. It is a round black component that points toward the flame. It has wires coming out the back.
Lets say your furnace turns on and sprays fuel in the combustion chamber but it does not light. The light sensor sees this thereby causing the control to shut down the furnace after 45 seconds or so. Now imagine the furnace kept running for several minutes(with no safety) and suddenly decided to light with a huge amount of excess fuel in the fire chamber. Not a pretty sight.
“It needs to be cleaned. The heat exchanger is choked up.”
True. That would have the same effect as a plugged flue or chimney if it were plugged to the point of exhaust restriction.
Contaminated fuel?
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