Oil Burner Puffback questions & answers:

Frequently-asked questions & answers about the cause, cure, and prevention of oil burner puffback explosions that can blow soot and oil burner fumes throughout a building.

Oil burners, used on heating furnaces, boilers, water heaters, calorifiers, cylinders, or other heating appliances can, improperly serviced or adjusted, cause puffbacks that can be dangerous, as well as expensive.

This article explains the cause, cure, and prevention of potentially dangerous and sooty oil fired heating equipment puffbacks that can occur at an oil fired boiler, furnace, or water heater.

FAQs on Sooty Puffbacks at Oil-Fired Heating Equipment

These Questions & answers about oil burner puffbacks & puffback explosions were posted originally at OIL BURNER SOOT & PUFFBACKS - be sure you read through the causes, cures, and prevention for puffbacks given there.

Watch out: if the reset button on your heating equipment has popped, you might press it ONCE to see if the equipment will run and provide heat (or hot water) while you wait for repair service.

But do not keep pressing the button repeatedly as doing so, particluarly if the burner does not run for 10 minutes or more, risks a dangerous puffback explosion when un-burned fuel in the heater finally ignites - causing a puffback explosion.

At AQUASTAT RESET BUTTON we list the location of all of the various reset buttons and controls found on heating equipment.

Reader Question: Do "faulty boilers" cause puffbacks? Where do I look for puffback damage to the boiler itself?

Thank you for your informative website. As a homeowner trying to deal with a puffback it is a sight for *dirty* eyes!! Under the heading
What Causes Sooty Puffbacks at Oil-Fired Heating Boilers, Furnaces, Water Heaters [article above] there is a statement in paragraph one that states "Depending on the quantity of oil that is ignited, the puffback can damage the boiler itself...".

This seems to be the opposite of what my insurance carrier is telling me. They maintain that a faulty boiler causes a puffback and thus is not covered under the homeowners policy because it is the culprit, only the damage it causes is.

Where would I look to determine what, if any, amount of unburned oil could have actually damaged my boiler? Thanks, D.F.

Our InspectAPedia photo (above left) shows soot on the ceiling of a garage just outside a boiler room where an oil-fired heating boiler was operating improperly and blowing soot into the building - a puffback from this system was imminent. This is not the building discussed by D.F. above. As you can see by the exposed wall studs in the right side of the photo, we had already begun demolishing the sooty drywall in this home.

Follow-up:

Thank you so much for your answer. I have since learned a bit more about boilers and would like to correct some confusion with my wording now. I do apologize as boiler jargon is really not my thing. My boiler has been maintained but it is aged. I had shut down the system for the season, or so I thought. It was an unusual damp, wet May. I suspect one of the kids hit the on switch at the entry to the basement.

Regardless, since the boiler has to be replaced I am trying to learn. I am trying to understand the term *inherent vices* of a boiler that exclude replacement coverage under the homeowners policy.

I am coming to understand that there are some condition that are known to cause the boiler to "damage itself". In other words, wear and tear, causing a puffback.

However, the wording in your article led me to question whether the oil/puffback could be an "external" element that caused the damage to the boiler. Its sorta like what came first, the chicken or the egg. There were no visible leaks so I am wondering how the "excess oil" could have gotten there.

Are there any possibilities that tie in the oil tank (outside underground)? Either way, I am learning it is an uphill battle to actually get the boiler replacement cost covered which; is a real expensive bummer. After all, protecting against a big expense like this is why you buy insurance in the first place.

Reply: Do faulty boilers cause puffbacks? No, oil burner problems, oil piping leaks, or chimney maintenance troubles are the root cause of puffbacks.

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with or cause of malfunction in a heating boiler. That said, here are some things to consider:

Your quotation from your insurance company stating that the puffback was caused by a "defective heating boiler" is confusing because it is not a precisely correct description of heating equipment puffback problems.

The explanation we offer of the mechanism of a puffback in oil fired heating equipment is more detailed than a typical insurance adjuster would offer even if s/he understood the cause of puffbacks, but our explanation is also the correct one.

Our photo (above left) shows soot fragments on top of a water heater that was installed close to an oil-fired heating boiler that was not operating properly - the same boiler whose soot was deposited on the garage ceiling and walls in our earlier photo just above.

Failure to notice and do something about this sooty boiler operation is a failure to notice and correct a boiler operation or maintenance problem.

On 2018-01-22 by (mod) - Risk of a puffback explosion: what's the actual noise?

Kelly

You may be hearing the sudden ignition or 'explosion' of un-burned oil that collects in the combustion chamber if an oil burner is not working properly.

Watch out: such explosions can be dangerous as well as making a sooty mess of a building. Ask your heating service company to inspect and repair or adjust the system.

On 2018-01-22 by Kelly Mingus

What causes water sound in my vent and black smoke came out of the vent once. There is a boiler system here.

On 2018-01-14 by (mod) - oil burner puffbacks can be dangerous

Peggy

Your neighbor's oil burner is or was not working properly and was probably unsafe.

The chief material in black ash from an oil burner is soot.

That can be hazardous, DEPENDING on the duration and level of actual exposure. That's not something one can assess by e-text. But you will read in the research I'll cite below that principal hazards are from acute exposure such as that experienced by oil burner service technicians.

See this

Research on the Hazards of Oil Burner Soot & Exhaust & oil burner puffbacks

• Armstrong, Janice Gray, Deborah Gangloff Dowd, Martha V. Pike, and Susan Stitt. "A furnace puff-back: the unique problem of soot on objects and costumes." In Preprints of papers presented at the ninth annual meeting, Philadelphia, Pennsylvania, 27-31 May 1981 (American Institute for Conservation of Historic and Artistic Works), pp. 10-19. American Institute for Conservation, 1981.
• Boyland, E. "The toxicology of soot." In Soot in Combustion Systems and Its Toxic Properties, pp. 13-24. Springer US, 1983.
• Fallentin, B., and J. Frost. "Health Hazards from cleaning Oil-Fired Boilers caused by Vanadium and Sulphuric Acid in the Soot." Nordisk Hygienisk Tidskrift 3/4 (1954): 58-65.
• Thilly, William G. "Soot components as genetic hazards." In Soot in Combustion Systems and Its Toxic Properties, pp. 1-12. Springer US, 1983.
• Lahaye, Jacques, ed. Soot in combustion systems and its toxic properties. Vol. 7. Springer Science & Business Media, 2013.
• Lu, Pei, Caiting Li, Guangming Zeng, Xuwen Xie, Zhihong Cai, Yangxin Zhou, Yapei Zhao, Qi Zhan, and Zheng Zeng. "Research on soot of black smoke from ceramic furnace flue gas: Characterization of soot." Journal of hazardous materials 199 (2012): 272-281.
• Ohlström, Mikael O., Kari EJ Lehtinen, Mikko Moisio, and Jorma K. Jokiniemi. "Fine-particle emissions of energy production in Finland." Atmospheric Environment 34, no. 22 (2000): 3701-3711.
• Williams, Nigel. "Vanadium poisoning from cleaning oil-fired boilers." British journal of industrial medicine 9, no. 1 (1952): 50.
  

On 2018-01-11 by Peggy

My neighbors chimney spewed ash all over our yard and house and cars. They heat with oil and yesterday a new furnace was put in. However I want to know if the stuff from their chimney is a health issue for us and our pets? It is all over our dog and covers the entire block in our area. thanks, Peggy

On 2017-11-27 20:44:06.604956 by (mod) -

MIke,

There are multiple possible causes for sooting and puffbacks, mostly traced to a need to clean and service the oil burner system. If the soot and fumes are more than trivial I'd turn off the system to avoid a possible puffback and then call for emergency heat service.

On 2017-11-27 by Mike

My oil burner is leaking fumes from boiler and some soot escaping when turned on what to do

On 2017-11-15 by (mod) -

MIke

I'm not sure what parts you're describing. Can you use the page bottom CONTACT link to send me photos or a copy of the parts explosion from your boiler's IO manual?


Edie:
Black soot from a gas appliance is VERY dangerous, as it's a sign of incomplete combustion and a risk of potentially fatal carbon monoxide poisoning. Be sure that you have properly located, installed, and tested CO and smoke detectors. Turn off the heater, and call for repair by a local gas appliance service company.

On 2017-11-15 by mike

what does a flange look likeinside a burnham boilerthat goes around the heatshield and what function does this prvide?

On 2017-10-27 by Edie

We ran natural gas from the road to our home( long distance). We built a beautiful fireplace with cabinets.

Go to two years. My house walls, windows ceiling are blacked. Yesterday my heart became more burdened. I was getting cobwebs down and noticed that my entire bedroom walls were covered with a heavy dust. My fan and light are black. Now it’s time to use my fireplace again.

My house can’t get any more dirty. We had a man come and adjust the opening where I guess the gas come out. I this didn’t work. We are ordering g new logs today. I have cleaned them but I don’t know what to do.

We bought this gas heater out of a home and they were using it. Do I get a new one or what kind if company would work on this gas heater. We don’t have a gas store where I live. We have called our gas company and they don’t have any numbers of companies. Sad

On 2017-10-22 by (mod) - some oil burner soot is normal

Soot from oil fired equipment is normal as the system gets dirty internally during a season of operation.

Annual service is essential for oil fired heating equipment. But abnormal sooting, soot blowing out of the heater or out of the flue or damper is unsafe and would require service, cleaning, repair and a check of the chimney.

The problem could be trivial: a clogged oil burner nozzle, or something more difficult to find and correct.

On 2017-10-22 by Jane

My oil boiler is 3 years old. Serviced annually. I have had a large build of soot which plumber cleared. What has caused this build up and is it dangerous?

On 2017-09-24 by (mod) - more causes of oil burner puffbacks

Nigel,

There are a number of problems that can cause the puff back malfunction that you described. I can't list them all off the cuff and besides your on-site expert needs to look and find the actual problem.

Examples however include insufficient combustion air into the space where the burner is operating, or even a leaky or incorrectly installed or incorrectly selected oil burner nozzle or nozzle adapter.

Even a small air leak in the oil line can cause the problem that you described. So can I block chimney or flu. So Further investigation by an experienced service technician is needed to check out the basic metrics such as combustion air, flame pattern, draft, in order to get an idea of the direction to look for the problem. Let me know what you're told and I can come in further.

On 2017-09-24 by Nigel

My old Trianco boiler was seviced this week and the engineer changed the air flow incorrectly causing bad misfire. Came back to change settings back to what is was previously but still did not solve problem.

Then third visit by a supposedly more experience engineer. Seemed to be running weel when he was here. Following day boiler did not fire up on start (reset light on).

On nexr start up attemp there was a big blowback blowing the flue off the the top of the boiler and the top off the chimney! Obviously not happy at all but where do I go now?

This is obviously going to cost me big to repair the chimney and flue even if the boiler is still alive! Any suggestions as i'm sure I want these guys any where near my place after this!

On 2017-04-08 by (mod) - If a heating system chimney is leaking

John

If a heating system chimney is leaking anything - including exhaust or fumes - into the building, the chimney and heating system are unsafe, risking fire and (particularly when gas fired equipment is being vented into a flue) fatal carbon monoxide poisoning.

I can't diagnose your situation by e-text but from what you describe there are serious, possibly fatal safety hazards in the building - the management, occupants, etc. need to know that immediately.

On 2017-04-08 by john niemela

My Super,Last Summer Fired Up The Boiler,My Sisters Apartment is on the 5 th floor,She Has Holes in Her Ceiling,The Entire Apartment,was Filled with Boiler Fumes,Now,The Fumes shoot out of the chimney,before this genius,the fumes were 1 ft above the chimney,now,they re 10 feet in the air,Did something go on the 5 th floor as far as the chimney,a plate or something else?

Question: What's the cause​ of oil burner getting on fire?

(Apr 3, 2017) Maria said:

What's the cause​ of oil burner getting on fire. Dark some from the chimney, co2 inside if house...High levels. After the cleanup and service been performed..Still can smell burning oil...that's 3 days later.

Reply:

Maria

I'm not sure if you are asking about a fire at the oil burner or a chimney fire.

Watch out: But it sounds as if your heating system is unsafe and should be turned off immediately,

then call your heating company, speak to the service manager, tell her that your system was just serviced but that now it is smoking, not working, and had to be shut down to avoid risking a puffback explosion.

On 2017-04-08 by john niemela - Fumes & smoke shoot 10 feet up out of the chimney

My Super,Last Summer Fired Up The Boiler, My Sisters Apartment is on the 5 th floor, She Has Holes in Her Ceiling,The Entire Apartment,was Filled with Boiler Fumes, Now, The,before this genius, the fumes were 1 ft above the chimney, now, theyre 10 feet in the air, Did something go on the 5 th floor as far as the chimney,a plate or something else?

On 2017-04-08 by (mod) re: dangers of chimney leaks into a building structure are serious

John

If a heating system chimney is leaking anything - including exhaust or fumes - into the building, the chimney and heating system are unsafe, risking fire and (particularly when gas fired equipment is being vented into a flue) fatal carbon monoxide poisoning.

I can't diagnose your situation by e-text but from what you describe there are serious, possibly fatal safety hazards in the building - the management, occupants, etc. need to know that immediately.

Question: Olsen furnace ran for about 30 seconds while smoke emanated from the ductwork going into furnace

On 2017-03-30 by Gary

Why is there oil going into the boiler when the oil is turned off . When turned back on it sending out a lot of smoke and smell

(Oct 14, 2017) Nick said:

We have an Olsen oil furnace that is not firing when we turn up the thermostat. went down to the furnace, and pressed the red reset button once on the beckett motor. it ran for about 30 seconds while smoke emanated from the ductwork going into furnace. quickly filled crawlspace with smoke.

shut off the burner switch and put the thermostat at 0. any thoughts on whats going on?

Reply: it ran for about 30 seconds while smoke emanated from the ductwork going into furnace

Gary and Nick:

Watch out: LEAVE THE BOILER OFF right away to avoid a puffback explosion.

Most-likely the automatic oil line shutoff valve/check valve in your fuel unit (oil burner pump) is sticking open. Sometimes we make a temp fix by adding an oil delay/stop valve on the line between the fuel unit and the burner nozzle oil line inlet.

On 2017-01-20 by Isaac - loud bang from the oil tank

We have a oil burning furnace with two large tanks in the basement. We randomly hear a very loud bang coming from the tanks of furnace when the system is not running. I see no signs of a puffback. Do you know what this could be?

On 2016-12-17 by (mod) re: obtaining outdoor air supply for an oil burner

You can certainly obtain an outside air supply for the oil burner - as some systems provide a duct that brings outdoor air to an enclosure around the oil burner. You need about 1 sq.in. of un-screened air intake opening per 1000 BTUH.

On 2016-12-17 by K Purcell

I have an oil-heated hot water tank. We have a workshop in the basement and dust gets into the burner. My oil-heated furnace has a metal cover over its burner. Can I get or make a cover for the burner for my oil-heated hot water tank? It is a Brock.

On 2016-11-28 by Joe

I have a bekett furnace and I get a big puff back the chimney I pipe is clean and the flame looks good the furnace starts good and shut off ok but sometimes I get a bang in the furnace and it blows the damper off the pipe.

On 2016-02-01 by Joe from Brooklyn

thxs

On 2015-12-01 by (mod) re: inadequate combustion air causes smoky oil burner flame

Good going, Rob; indeed inadequate combustion air will give us a smoky flame; at this point a worry remains that the nozzle assembly is sooty and dirty; keep an eye on how the system is running.

On 2015-11-30 by Rob

found the air intake was packed with lint and dust. looks like it was never cleaned.
cleaned it out and reset the air

everything seams to be going well...time will tell
thanks for the reply

On 2015-11-30 by Rob

also getting allot of black smoke from my chimney

On 2015-11-30 by (mod) - a tiny puff back on ignition

Perhaps your system has an air leak in the oil piping

On 2015-11-30 by Rob

I just cleaned my boiler chamber and removed jacket and cleaned sections and chimney base. Also replaced the filter, nozzle and electrodes just because I was in there and they looked a little caked up. Everything appeared to be running great but now I am getting a tiny puff back on ignition.

I have no leaks so I don't think any air is trapped and I have good draft so no blockage in chimney.
Any ideas on what could be causing this?

Question: Help with an oil-flooded water heater that caught fire

I have a oil fed hot water heater, the primary ignition relay malfunctioned , causing the hot water heater to have excessive amount of fuel inside furnace chamber.

I cleaned as much of it. replaced the primary ignition ,When restarted the hot water heater spews dark gray smoke from chimney, also noticed when I shut hot water heater off,

I ck'd access hole to furnace(hot water) there was a fire inside. I put out fire with water. I need help - Matt

Reply: flooding the water heater ignited unburned heating oil and risked a "puffback" - clean or R&R oil-soaked combustion chambers before re-igniting the burner

Matt, fresh out of oil burner school we were always terrified about lighting off an oil burner into a previously flooded combustion chamber and flat wouldn't do it if we hadn't cleaned the system and even removed/replaced oil-soaked combustion chamber liners. And if the chimney was of unknown condition we'd have it inspected (Chimscan, the works) - even so, it was not unusual to call the fire department and have them on stand-by: that's what we were taught to do.

The first time I called the fire department to ask them to go on stand by while we fired up the boiler, the fire department operator said "maybe you should get someone in there who knows what they're doing" - which didn't inspire much confidence.

Now that you've had a fire you really cannot safely turn the equipment back on before an expert inspects the chimney and flue for safety;

A modest oil residue in the combustion chamber can be burned off. But a really flooded chamber deserved to be disassembled and cleaned or replaced.

Question: soot blamed on power vent and chimney, reappears after clean-up

(Dec 5, 2014) Amy said:

I had a problem this past spring with black soot throughout my home. We had 2 different companies plus a mechanical engineer come in to determine that the furnace was fine and that the cause of the black soot in the house was from the power vent.

We got the house cleaned by a fire cleanup services company and all the rooms were painted because they couldn't get the soot all out. We replaced the power vent with a chimney.

I am beside myself that I have again found the black soot coating white plastic containers in my kitchen cupboards. I have contacted a materials lab and was told that I would need a good amount of the soot in order for them to test it. This could take a very long time to collect because it's a black film that smears.

I don't know what else to do or who to turn to for help. I can't go through what we did this past spring. Do you have any thoughts and or recommendations as to what I can do? Thank you for your time!

Reply:

Sorry to read about this soot Amy - perhaps the original diagnosis was erroneous. After all, a sooting-up oil fired heating system can clog a power vent just as it can clog a flue vent connector, heat exchanger, or chimney.

You need help from a trained and experienced heating service tech.

Let me know what you're told.

Question: diagnose oil smell in a NYC Building with Gas boilers but oil burner next-door

(Feb 21, 2015) Landlord said:
Is it possible for a malfunctioning oil furnace to be the cause of an oily smell in an adjacent building that has gas boilers? I own a brownstone with four apartments. The building has four gas boilers but the attached brownstone next door has an oil furnace.

There is a smell of oil particularly in the ground floor apartment that is worse on very cold days.

The smell began with the very cold weather about six weeks ago. The fire department and gas company have ruled out a gas leak and the boilers have been inspected.

There is also a smoky looking streak on a wall where
a wall and floor come together but it is not on a wall adjacent to the building with oil heat.

The smell has been described as oily, a chemical electrical smell, and a burned out candle smell. Any advice would be greatly appreciated.

Reply:

Land

It's a fair question but not one that I think we can diagnose from just an e text. A thoughtful onsite inspection may help. Start at the oil storage and piping system, oil burner operation, and possible fuel or fours gas pathways.

(Feb 24, 2015) Landlord said:
Thank you for your response.

Given that I do not own the oil furnace in question or have ready access to it, an inspection is not easy to do currently.

The question now is this: given the information in the first message, is there enough evidence to inform the neighbor with the oil furnace that the furnace may need attention?

Could there be a danger to my tenants from this oil furnace? If so, Is there a city/ government agency (in NYC) that follows up on a situation like this? Thank you for any advice you can offer.

Reply:

Land:

I really would like to help but with no actual information about the property I can't buy enough liability insurance (don't have any at all) to bet your safety or that of others by speculating when I am flying so blind.

It's fair to say that if there are gas odors in a building most people can identify that accurately as the odorants in natural gas or LP gas are rather recognizable - and that'd be enough to raise a safety concern. You say there have already been expert inspections, leaving me confounded.

NYC agencies involved include the fire department, building department, and the NYC Housing Department

Question: is a puffback dangerous to your health?

(Mar 17, 2015) Joan Thorson said:
We had a puffback in our home is this dangerous to our health? Ins. co being notified.

Reply:

Joan it's a fair question to ask but not one that can be assessed by an e-text. Sure, breathing oil burner soot is potentially hazardous - it depends on the dose and exposure duration as well as individual health and vulnerability. If you or any occupants have reason to feel concerned I'd check with the family doctor first.

Also see HEATING OIL EXPOSURE HAZARDS, LIMITS

and see SOOT on OIL FIRED HEATING EQUIPMENT

And of course any explosion can be quite dangerous.

...

Continue reading at OIL BURNER SOOT & PUFFBACKS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• OIL BURNER INSPECTION & REPAIR - home
• AQUASTAT RESET BUTTON
• OIL SUPPLY LINE PIPING LEAKS
• FIRE & SMOKE ODOR REMOVAL

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OIL BURNER PUFFBACK FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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