what causes soot in furnace

Outside of fires, some common causes of soot issues include:

Full Answer

What causes soot in a propane furnace?

Soot is a byproduct of incomplete propane combustion, and it builds up in a furnace when the furnace isn't cleaned regularly. When a fire burns in the fireplace, invisible hot gases surround it when it's burning bright.

What happens if you have black soot in your furnace?

This is the biggest issue. If black soot is found near where the furnace connects to the ducts, the heat exchanger may be leaking. This can cause combustion byproducts like soot to mix with the air in the house. Carbon monoxide can also be released in this fashion, which is highly toxic.

Why is black soot coming out of my vents?

Black Soot from Furnace Black soot can build up inside the combustion chamber of a furnace due to a lack of routine maintenance, but this soot shouldn’t end up in the ducts or coming out of your vents unless there’s a serious problem like a puff back.

Why is there soot in my oil burner flue?

Seeing debris, soot or rust flakes in the flue vent connector or on the horizontal surfaces near the furnace is a sign that it needs any of the following: cleaning and servicing, a replacement heat exchanger, or burner adjustment. A little oil burner soot (no more than 1/8 inch) after the appliance receives maintenance services is normal.

How do I stop my furnace from sooting?

Switch to a higher quality fuel. Low grade fuels create more soot when burned, especially if you have an oil furnace, and you may be able to reduce your furnace's soot production simply by using a higher grade of fuel.

What causes soot build up in heat exchanger?

Soot Build-Up Soot develops due to accumulations of carbon within the furnace. This is usually the case when the furnace is not clean and completely burning fuel, as the result of a poorly adjusted burner or a cracked heat exchanger.

Why is my furnace blowing soot?

Soot is the result of incomplete combustion, meaning that your furnace isn't burning the gas properly or efficiently. Soot can be deposited on the heat exchanger, acting as an insulating barrier. This insulation barrier lowers your furnace's efficiency, increasing your energy bills as a result.

What causes soot buildup?

Soot forms as a result of incomplete combustion. To achieve incomplete combustion instead of complete combustion, the fuel must burn at a lower temperature with a slightly reduced supply of oxygen. When the fuel burns, it breaks into small particles that include soot, which settles out as a dark powdery deposit.

How do I prevent soot buildup?

To prevent soot and creosote buildup, burn only dry, well-seasoned hardwood and encourage briskly burning fires rather than slow, low-temperature flames by stoking a fire frequently or ensuring ample inflow.

How can we reduce soot formation?

Pressure increasing more than 0.8 MPa, decreases the soot formation with increase residence time. It was suggested that this might result from higher radiation losses leading to lower temperature and lower soot formation rates (Treea and Svensson, 2007).

How do I know if my furnace vent is clogged?

How to tell if your exhaust vent is blockedFurnace doesn't heat the air. By far, the most common symptom of a blocked exhaust vent is a furnace that doesn't heat up. ... Furnace heats up for a little while, then shuts off. ... Furnace cover panel gets hot. ... Bad smells when your furnace is heating.

Why is my house full of soot?

Any material that can burn can produce soot, including natural gas, LP, wood, oil, candle wax, gasoline, diesel fuel, tobacco smoke, dust, dirt, cooking oils, and carpet fibers. Sources include: * Unvented fossil-fired heating appliances, such as space heaters, kitchen ranges, and clothes dryers.

How do I know if my heat exchanger is clogged?

Six Signs Your Furnace Heat Exchanger May be CrackedStrange smells. A malfunctioning heat exchanger will often create an unpleasant and strong odor that smells similar to formaldehyde.Soot Build-up. ... Corrosion & Cracks. ... Change in the flame appearance. ... Audible Sounds. ... Presence of Carbon Monoxide.

Can breathing in soot hurt you?

So, to answer your question, yes, black soot can be dangerous and even fatal to some people. Essentially, soot gets into the human body through ingestion, inhalation, or through the skin and eye. When in the body, soot particles can cause coronary heart disease, breathing issues, including asthma, and even cancer.

What problems do soot cause?

Soot can enter the body through inhalation, ingestion or via the skin and eyes. These toxic particles can cause breathing issues, including asthma, bronchitis, coronary heart disease, and even cancer. Infants, the elderly, and those who already have breathing problems are the most affected.

Can soot damage your lungs?

Similarly, soot is equally as dangerous for your health because it enters and settles deep into your lungs causing serious health issues. Heat Damage – This is thermal damage to the body's tissues. The respiratory tract is especially vulnerable if you inhale smoke or soot at high air temperatures.

How does soot affect the heat exchanger?

Every boiler is a heat exchanger, there's a fire side of the tubes, and a water side. There are two main factors that can affect heat transfer. Soot, a product of improper combustion, can insulate the tubes on the fire side, preventing the exchange of heat from the flue gasses to the tubes.

What is the reason for soot deposition on boiler tubes?

A firetube boiler has tubes that carry hot gases. The tubes are surrounded by water that is heated. The hot gases flowing through the tubes carry the by-products of combustion, primarily soot and scale, which are deposited on the inside surfaces of the tubes.

How is soot formed HVAC?

As the furnace in your house burns fuel to create heat, especially natural gas, there are remnants left over after the process is completed. This is called “incomplete combustion.” One of the combustion byproducts is carbon, the primary ingredient in black soot, which is sent up the heat exchanger and out of the house.

What are the symptoms of a damaged heat exchanger?

Six Signs Your Furnace Heat Exchanger May be CrackedStrange smells. A malfunctioning heat exchanger will often create an unpleasant and strong odor that smells similar to formaldehyde.Soot Build-up. ... Corrosion & Cracks. ... Change in the flame appearance. ... Audible Sounds. ... Presence of Carbon Monoxide.

Why does my furnace have soot?

In a normal heating setup, however, the system vents out the soot alongside other byproducts of combustion. Venting problems, such as blockages or damage, can cause the soot to accumulate in the house/furnace instead of venting out.

What causes soot to be produced?

1. Incomplete Combustion: Soot is a common byproduct of combustion — it represents incomplete combustion. Thus, a high degree of incomplete combustion leads to more soot produced. Common causes of incomplete combustion include:

What happens if a heat exchanger cracks?

If the heat exchanger cracks, it can allow the byproducts of combustion to spill into the neighboring environment.

Why does my pilot light keep going off?

A dirty pilot light might fail to light or keep going off. The result is an inefficient heating and incomplete combustion that leads to further soot production.

What causes too much fuel in the combustion chamber?

Fuel valve malfunction that leads to too much fuel in the combustion chamber

What causes carbon monoxide in the air?

3. CO Poisoning: In many cases, the malfunctions (such as cracked heat exchanger) that increase soot production also cause carbon monoxide (CO) production. The CO can contaminate your indoor air. CO is a poisonous gas whose inhalation can cause respiratory problems or even death.

Can you ignore soot in your heating system?

As you can see, you shouldn't ignore soot in your heating system. Don't just wipe off the soot and operate your heater as usual. Find out why your heating system is that sooty and fix the problem. Contact services like Mauzy Heating, Air & Solar if you need heating repairs.

What causes soot in an oil furnace?

Causes of Oil Furnace Soot. By Richard Hoyt. Hunker may earn compensation through affiliate links in this story. Unburned carbon and sulfur in the fuel burned in oil furnaces, often in the form of black smoke filled with particles, is called soot. The two main reasons that oil furnaces produce soot is puffback and the accumulation ...

Why does my furnace blow soot?

Unburned oil on the bottom of the combustion chamber of the furnace can ignite, causing an explosion called puffback. The explosion can disconnect the flue vent connector , also called the stack pipe, causing soot to blow through your house. The three main reasons for incompletely burned oil that causes puffback are a leaky fuel line, a bad shut-off valve, and when the nozzle that shoots oil into the furnace becomes clogged.

How to clean soot stains from walls?

Before attempting to clean up soot stains, put on gloves, safety goggles, a dust mask, and other protective gear. There are several soot-removal methods, including wiping walls with soot sponges and scrubbing walls with vinegar solutions or trisodium phosphate (TSP).

Where does soot come from in a furnace?

Soot gathers at the base and on the walls of both metal flues and masonry chimneys that vent smoke from oil furnaces. If the base of a metal flue is not cleaned, the soot can burn, producing toxic carbon monoxide that can spread through the ducts to all parts of your house.

Why does my oil furnace make a rumbling sound?

If your oil furnace makes a soft rumbling sound when you turn it off, it might not be shutting down completely, and oil is accumulating on the bottom of the burner. If you see soot on top of your furnace or black stains on the walls of ceilings around the furnace, a more serious soot problem may be developing. Advertisement.

What happens when oil leaks from a furnace?

If the pipes that carry oil to the burner leak oil when the furnace is not running, air may enter the burner where it is compressed. When the burner stops running, compressed bubbles of air expand, pushing heating oil into the chamber where it accumulates. When this pool of oil ignites, it explodes as puffback.

Why does oil puff back in furnace?

If the spray nozzle that shoots oil into the burning chamber becomes partly blocked, not all of the oil sprayed into the chamber is burned. This, too, can cause unburned heating oil to accumulate on the bottom of the furnace--a potential cause of puffback.

What is soot in a furnace?

Soot is a byproduct of incomplete propane combustion, and it builds up in a furnace when the furnace isn't cleaned regularly.

Why is soot unnoticeable in furnaces?

But hardly anything in the real world is ideal, and a small amount of soot is unnoticeable because it stays inside the furnace's heat exchanger. There's a problem when buildup inside the heat exchanger becomes excessive, however.

How to tell if heat exchanger is leaking?

If you notice soot on any of the components inside the furnace, on the floor or walls of the furnace room or around any of the vent openings in your house, it means the heat exchanger is leaking. If so, soot — messy as it is — is the least of your problems, because the furnace is also leaking combustion gases, including carbon monoxide. Carbon monoxide is odorless and deadly, and if you don't have carbon monoxide detectors to warn you of its presence, you're in real danger.

Why does my propane bill increase?

If you notice a gradual increase in your propane bill, that could be the reason, because the furnace has to stay on longer ...

What happens if you don't clean your heat exchanger?

If you don't clean your burners regularly and they get clogged with soot, one of them could actually explode, sending soot throughout the ductwork and setting you up for an expensive cleaning job . This type of explosion is known as a puff back, and it doesn't necessarily damage the heat exchanger, although it could.

What happens when a fireplace cools down?

When it cools down, the gases become thick and dense and turn to smoke, and the smoke turns into soot when it contacts the walls of the fireplace. The same thing happens inside the combustion chamber of a furnace. When the burners are clean and burning hot, they produce microscopic amounts of smoke and soot.

Why does my heat exchanger leak?

A heat exchanger usually leaks because it's cracked, and you can't fix it — you can only replace it. That's a job for the HVAC technician, whom you need to call as soon as you notice the problem. You should shut down the furnace and leave it off until the technician arrives.

Why is my furnace not producing heat?

Check the thermostat: A dead battery in a thermostat may cause the furnace to not produce heat. Make sure the thermostat is on “Heat” mode and that the temperature setting is higher than the room’s temperature. The fan should be on “Auto” so the blower doesn’t run continuously.

Why is my furnace not heating?

Insufficient heat: When a furnace doesn’t heat a space properly, it might be the wrong size, have a clogged filter, or have a problem with the pilot light. It is also an indication that the thermostat might be faulty. Excessive noise: While furnaces aren’t exactly quiet, they should not make strange noises.

Why does my furnace keep cycling?

Frequent cycling may be due to bad thermostat settings, a faulty thermostat, poor airflow, an exchanger issue or a clogged filter.

What to do if thermostat doesn't match furnace?

If the thermostat doesn’t match the furnace’s capacity and capabilities, you’ll need a replacement. Change the air filters regularly: Dirty air filters lead to several preventable furnace problems. Replace or clean the air filters according to the manufacturer’s instructions.

Why is my furnace pilot light yellow?

A yellow, faint, or irregular flame can be a sign that the burner is dirty,clogged, has a faulty ignition, a thermocouple problem, a cracked heat exchanger, or may be located in a drafty room. A yellow flame may also indicate that there is a non-ideal balance of gases surrounding the pilot light.

Why does my furnace make a loud noise?

Excessive noise: While furnaces aren’t exactly quiet, they should not make strange noises. Noises generally mean there is an airflow problem, a clogged burner, an ignition issue, or a mechanical problem. Blower continuously runs: A blower that’s always on may be the result of a faulty limit switch.

What are the problems with gas furnaces?

The following furnace issues require professional expertise: Excessive soot: Soot is a problem that can occur with gas-fired and oil furnaces. Excessive furnace soot causes the heat that the appliance produces to go up into the chimney instead of into the home. Excessive soot also poses a fire hazard and increases the risk ...

What is soot?

Soot is a mixture of extremely fine black particles that result from incomplete combustion. Its primarily made up of carbon, but can also contain trace levels of metal dust, chemicals, PCB’s, and several other carcinogens. Soot is different from charcoal and other byproducts of combustion because it is so fine. Soot is far smaller than dust, mold and dirt particles, allowing for entry into our lungs as well as our porous belongings.

What is black soot?

The fine black substance known as “soot” is still very much a problem in many homes. It can gradually accumulate in the corner of your home, causing discoloration and also appear suddenly after a fire. If you have soot in your home, you need to identify its cause and determine how you can remove it.

What are they types of soot damage?

Soot composition can vary depending upon its underlying causes. While all types of soot cause some darkening, soot can look completely black in more severe cases. Although most soot looks similar, some types can be harder to clean or cause more intense odors. Its high acidic nature can cause discoloration in paints and long term presence can also play a role in lingering smoke odors.

What to do if your home is sooty?

An experienced expert can help you identify any existing soot or smoke damage and create a plan for removing it. Don’t let your home or building suffer from unwanted soot and smoke damage.

Is soot dangerous to pets?

Soot is extremely dangerous to humans and pets because of its small size. As such, soot can very easily be inhaled into the small passageways of the lungs. Prolonged exposure to soot has ties to respiratory illnesses, heart disease, and cancer.

Can a fire cause soot?

Nevertheless, even houses that have not been affected by a fire can end up with soot problems. Whenever anything containing hydrocarbons is burnt, soot issues can occur. Outside of fires, some common causes of soot issues include: Poorly ventilated fireplaces, Constant candle usage, Defective home furnaces,

Is soot a byproduct of combustion?

Soot is different from char coal and other byproducts of combustion because it is so fine. Soot is far smaller than dust, mold and dirt particles, allowing for entry into our lungs as well as our porous belongings. Soot is extremely dangerous to humans and pets because of its small size.

What does it mean when you see soot on your furnace?

If you see soot, rust flakes, and debris in the flue vent connector (photo at page top) or chunks of black and brown sooty crud on top of horizontal surfaces near your oil fired heating equipment, this means that the heating system needs to be cleaned and serviced.

Why is soot bad for heating?

Because soot acts like an insulating coating, too much soot in a heating system causes problems.

Why is a heat scavenger on oil fired heating systems asking for trouble in my OPINION?

Second, a heat scavenger on oil fired heating systems is asking for trouble in my OPINION because the multiple passages provide obstructions that invite soot accumulation, clogging, and subsequent oil burner back-pressure in the combustion chamber, overheating or incomplete, sootier-still combustion. Laws aside I personally don't like these devices on oil fired heating equipment.

How does soot affect the transfer of heat?

Thus the transfer of heat into the building is reduced by soot in the heating equipment. As the soot layer gets thicker less heat is transferred and more of the heat simply continues to go up the chimney instead of into the building.

How long does it take for oil to get soot off a heater?

A little oil burner soot after service is normal: Because cleaning an oil fired heater disturbs soot and some of that leaks into the utility room, it's normal to see a very light coating of soot dust in the 24 hours or so after your heating system is cleaned and serviced.

Why is soot so thick?

Soot layers too thick in boilers or furnaces means we spend more to heat the building: Soot inside the furnace or boiler reduces the transfer of heat into the heating system's water (or air if it's a furnace). Thus the transfer of heat into the building is reduced by soot in the heating equipment.

What is a flue vent connector?

A flue vent connector ( (also called the "stack pipe" or "flue pipe") is the metal pipe that connects the oil fired heating appliance to a chimney in order to safely vent combustion gases outdoors.

Why is there black soot in my furnace?

Black Soot from Furnace. Black soot can build up inside the combustion chamber of a furnace due to a lack of routine maintenance, but this soot shouldn’t end up in the ducts or coming out of your vents unless there’s a serious problem like a puff back.

How to clean soot from furnace?

1. Puff Back Cleanup. A puff back is a serious problem that you should treat as an emergency. It occurs when excess fuel builds up in the combustion chamber of a furnace.

How to stop soot from escaping from furnace vents?

Finally, you can also cover the vents to stop the movement of soot as the ducts and furnace are cleaned and repaired. Use a few layers of cheesecloth and tape the material securely around the vent covers so soot doesn’t escape.

What to do if your furnace blows soot?

The oily residue must be neutralized and carefully scrubbed or wiped away to prevent damage to the drywall, carpeting, upholstery, and other surfaces the soot settles on.

What is the name of the explosion in a furnace?

Unfortunately, it only takes one leaky or clogged burner to create a dangerous situation leading to an explosion known as a puff back. A puff back sends soot throughout your ducts ...

When is it suitable to service the furnace?

Proficient plumbing and heating companies such as Riley Plumbing recommend that the unit be cleaned if the soot sediments found in the surroundings or around the flue are more than a millimeter. The soot problem is not likely to solve itself and regular maintenance is needed to help uphold high furnace efficiency.

Why is the pilot light coagulated?

It gets coagulated with soot after running for years or if there is a problem with the ventilation system that gets rid of the byproducts of incomplete combustion.

Is soot in ducts dangerous?

Soot in the ducts pose a critical risk. If it collects around the region where the ducts connect to the furnace, you may be dealing with a leaking heat exchanger. This will introduce the byproducts into the air around your house, contaminating the safe environment. The highly toxic carbon monoxide is likely to be released this way.