9 Signs You Have a Venting or Flue Issue

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A venting or flue issue can prevent your furnace from working properly and jeopardize your safety. It can cause a backdraft that sucks air down the flue, along with exhaust fumes, into your home. These fumes can include deadly carbon monoxide. Therefore, the situation is urgent and requires prompt heating repair. Here are the signs of a venting or flue issue to call a professional for:

  1. Condensation: Gas fumes that vent into your home will cool and condense as moisture. It can be seen on windows as gases condense on the cold glass. The same gases are likely also in the air, so contact a heating repair contractor immediately.
  2. Rust: Rust on the furnace’s front grill is a sign gas fumes aren’t properly venting. The moisture from the gases causes the metal to rust. Signs of a leak also include rust in the chimney, which can weaken its structure.
  3. Water Stains: A venting issue, especially one involving the chimney, can cause water stains on walls and/or ceilings near the flue. Water may be seeping into your home. Aside from indicating a problem with venting, water damage to walls can lead to mold and water can also rot the frame of your home.
  4. Creosote: Creosote is a black, tar-like material that builds up inside the flue. Cleaning it out is part of annual maintenance. But creosote should not form outside the flue or your fireplace (if you have one). Excess buildup can indicate a venting or flue issue. The causes can range from a fireplace or furnace producing too much smoke to a damaged chimney liner that must be replaced.
  5. Flue Lining Crack: Unless you have a fireplace and see pieces of chimney tile, it can be hard to tell if the flue lining is damaged. A cracked flue liner can lead to a house fire. It is easily identified during a chimney video inspection. Therefore, consider asking your heating contractor to include one in your annual maintenance visit.
  6. Leaking Exhaust Pipe: With high-efficiency furnaces, exhaust pipe leaks aren’t uncommon. Condensation should drain via the pipe to a floor drain. However, if the pipe is clogged or cracked, it can leak. If you have a standard furnace, a water leak can mean the exhaust pipe is corroded or has a loose connection.
  7. Bubbles in Leaking Water: Condensation leaks often coincide with gas leaks. Therefore, if you see water coming from the flue pipe, look for bubbles, which is a sign there’s a gas and possibly a carbon monoxide leak. When this occurs, evacuate your home and call for help.
  8. The Outside of the Vent Is Obstructed: Gases can back up into your home if the outside vent or chimney opening is blocked. Remove any leaves, twigs, debris, animal nests, or dead animals you can safely access.
  9. The Furnace Doesn’t Work: An exhaust flue blockage can prevent air from reaching the fan, and a safety mechanism will shut down the furnace. Otherwise, incomplete combustion can occur and dangerous gases can leak into your home. A venting or flue issue can cause the furnace to shut off soon after starting. You may also notice a hot front cover panel and strange odors from the unit.

How Do I Check My Furnace Exhaust Piping?

Rust or water streaks on the pipe can mean it is blocked. Remove the flue cap to check for clogs inside the flue pipe. Remove any visible blockages you can reach, whether caused by ash, debris, or animals. Call a professional if the clog is too deep or complex. 

What Are Some Common Flue Issues?

The most common issues include a restricted flue, which means the flue pressure is too high. High pressure can prevent exhaust gases from venting out of your home until they become concentrated enough to leak inside. An undersized flue can also cause venting problems. A large number of elbows, or bends in the pipe, can as well; they may slow down the flow rate of exhaust gases and increase the pressure.

How Can I Tell If My Fireplace Isn’t Venting Properly?

If you use a fireplace, a venting problem may be the reason it’s unusually smoky. A blockage may be preventing the smoke from rising through the flue as normal. The fire may be difficult to light, weak, or rise and spark suddenly.

What Are the Signs of Chimney Damage?

Cracks can form in the chimney crown due to freeze/thaw cycles. Water damage may not be limited to the chimney. It can also affect the flashing, which closes the gap between the chimney and the roof; replace any flashing that’s warped or deteriorated to prevent a leak. Also, look for structural damage such as crumbling masonry, missing bricks, black stains on top of the chimney, or if the chimney is leaning.

Call QRC to Address Your Venting or Flue Issues

At QRC, our trained, certified professionals ensure Winston-Salem’s home and business owners have reliable heating systems. We know how important it is for your furnace or heater to be functional, safe, and efficient. Venting or flue issues can cause property damage and indoor air quality hazards. Fortunately, our technicians promptly diagnose and repair any heating problem. If you notice any signs of trouble, call (336) 585-8408 today. We are available 24/7.