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Furnace and Boiler Puffbacks - What You Need to Know

What is a furnace puffback? What causes a boiler puffback? Click to learn everything you need to know about puffback prevention and clean-up services.

When temperatures drop, you turn on your furnace for the first time without a second thought. You don't expect a cloud of smoke or soot to shoot out. What you just experienced is a puffback.

But what is a furnace or boiler puffback exactly? Keep reading to learn more about this dangerous, messy and costly phenomenon.

What Is a Heating System Puffback?

A puffback is an explosion inside the heating system. It can occur when the unit misfires. In both furnaces and boilers, oil or gas vapors build up inside the combustion chamber. Turning on the system may cause a misfire inside the chamber, and when it finally does ignite, the excess oil or vapors explode. Puffbacks are especially common at the beginning of the cold season, but they can happen without warning at any time.

Unfortunately, a single puffback can cause significant damage. A large one may shoot smoke and soot throughout a home. Even a minor puffback may destroy the internal components of the heating system. These heating system explosions may damage your walls, ceiling or furniture. In the worst-case scenario, a house fire could erupt.

What Causes Puffbacks in a Furnace?

What is a furnace puffback, and what causes it? A furnace puffback is an explosion inside the ignition chamber. These explosions occur whenever your system doesn't properly ignite for several reasons, including excess gas or oil in the ignition chamber. Puffbacks can affect any gas or oil appliance, including your furnace.

There are several causes of furnace puffbacks, including:

  • Leaks in the oil supply piping
  • Malfunctioning shutdown valve
  • Clogged oil spray nozzle
  • Issues with combustion gas venting
  • Pressing the manual reset button too many times in a  row.

Furnace puffback warning signs include:

  • There is soot on the outside of the furnace.
  • The furnace blows out smoke or soot while in use.
  • You hear percussive sounds inside the ignition chamber when the furnace isn't running.
  • You notice a banging noise at the beginning of the burn cycle.

What Causes Puffbacks in a Boiler?

Puffbacks may also happen inside a boiler. Unlike furnaces, boilers use hot water to heat a home. However, boiler heating systems still rely on gas to keep water in the reservoir tank warm. Like furnaces, leaks in the system or a malfunctioning shutdown valve may cause gas to build up inside the boiler.

Problems inside the combustion chamber may cause a puffback. Excess gas in the chamber may cause the pilot light ignition to misfire, and a puffback may occur.

In a boiler, puffback warning signs include:

  • Fuel leaks around the combustion chamber
  • Dirt or debris blocking the venting
  • Cracks or leaks in the heating system

If you notice any of these issues, be sure to schedule repairs right away. Aire Serv® provides reliable HVAC maintenance and repairs that can prevent a puffback from happening. As a fellow member of the Neighborly® family of home service brands, Aire Serv is your trusted source for all your heating and cooling needs.

How Can You Prevent Puffbacks?

Worried about boiler or furnace puffbacks? Preventative maintenance is key. The earlier you catch a problem, the easier – and cheaper – it is to fix.

Follow these helpful puffback prevention tips:

  • Clean your furnace or boiler regularly. Make sure the area around your heating systems is free of debris and dust.
  • Trust your ears. Furnaces and boilers do make some noise while running, but you shouldn't hear loud banging or rumbling sounds. And you shouldn’t hear anything when the heating system is not in use.
  • Check for gas or oil leaks. A leaking boiler or furnace is prone to puffbacks. Look for visible holes or cracks in all the valves, piping and connectors.
  • Hire a professional technician to inspect and clean your heating system each year. Technicians have the tools and training to detect problems before they get out of hand.
  • Install a carbon monoxide detector near your heating system. Puffbacks release carbon monoxide into the air. This odorless gas can harm your family. A carbon monoxide detector won't stop a puffback, but it will alert your family to evacuate.

Cleaning Up After a Puffback

Puffbacks leave behind a costly mess. Depending on the size of the puffback, soot and smoke may fill your home. It can even travel through the air ducts into other rooms. You don't want your family to breathe unhealthy air! Black soot may damage the walls, furniture, window coverings, carpets and ceiling.

Choose Rainbow International for Professional Puffback Cleanup

The aftermath of a puffback is often overwhelming. Rainbow International can help if a puffback left you with a soot-stained and smoke-filled home. We specialize in fire and smoke restoration. Call us at (855) 724-6269 or request an appointment online to begin the puffback cleanup process.