How to Vent a Garage Heater

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Things You'll Need

  • Tape measure

  • 4-inch sheet-metal galvanized duct

  • 4-inch sheet-metal galvanized elbows

  • 5-inch hole saw

  • Cordless drill

  • Snips

  • Pipe crimper

  • Sheet-metal screws

  • 2-foot piece of 4-inch B-vent pipe

  • 4-inch B-vent termination cap

  • Galvanized hanger strap

  • High-temperature silicone caulk

  • Caulk gun

Image Credit: Jupiterimages/ Images

Garage heaters use natural gas as a source of combustion to provide heat in your garage. The natural gas produces toxic gases like carbon monoxide when it is burned. These gases must be vented to the exterior of the garage, where they are dispersed into the outside air. If they are not properly vented out of the garage, they can cause serious harm to people inside the garage. Typically the gases are vented from the heater to the outside of the garage with galvanized sheet-metal duct. With a few tools, it is easy to vent a garage heater.


Step 1

Measure the distance from your garage heater to the exterior wall you want to vent the heater out of. Purchase the required amount of sheet-metal duct and fittings.

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Step 2

Drill a hole through the exterior wall of the garage with a 5-inch hole saw.


Step 3

Run your 4-inch galvanized sheet-metal duct toward the hole you drilled, starting at the garage heater. Connect one piece to the next by inserting the crimped end into the non-crimped end. Screw each connection together with four sheet-metal screws.

Step 4

Cut the duct down as needed with your snips to make shorter pieces. Crimp one end of the cut pieces with your pipe crimper. Use elbows to make turns in the duct run. Stop the duct run 12 inches before the exterior wall of the garage.


Step 5

Insert the 2-foot piece of 4-inch B-vent pipe through the hole in the garage wall from the outside in. Connect it to the duct run with four sheet-metal screws.

Step 6

Connect the termination cap to the B-vent pipe. Align the cap until the locking mechanism lines up. Push it on and twist it to lock it into place.


Step 7

Caulk all seams and connections with high-temperature silicone caulk. Also caulk around where the pipe penetrates the building with high-temperature silicone caulk.


Support your duct run every 5 feet with galvanized hanger strap. Screw one end of the hanger strap to a ceiling joist, wrap it around the pipe and secure the other end to a ceiling joist. The hanger will look like the letter U when complete with the pipe in the middle.


Use B-vent pipe to penetrate your exterior wall. The venting for garage heaters can get extremely hot and B-vent pipe is insulated to keep the exterior of the pipe safe for penetrating combustible materials. If you use single-wall pipe to penetrate the exterior wall, a fire may result.


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