Venting A Gas Furnace Through The Roof

Gas furnaces usually come with their own specifications.

Venting a gas furnace through the roof.

So which type of venting system should your furnace have. Venting through a roof vent or exhausting them in the attic could cause moisture problems and rot. Place the vent cap on the top end of the duct and tighten the set screws with a screwdriver. The exhaust system typically uses metal venting often routed into a chimney stack to exhaust the combustion gases created in the furnace fire chamber.

With the exterior complete you can finish the rest of the job inside your garage. Adhere to them even if you are building the vent on your own. Put a cover on the vent. The diameter of the vent pipe should always be larger than that of the gas furnace flue ensuring that no gas escapes from the pipe.

You ll need to measure the distance between the rafters where the duct will go through the roof. A conventional natural gas furnace will vent the dangerous combustion gases through a simple vertical exhaust system that is attached to the furnace. If your furnace has an afue rating of 90 or lower it probably exhausts the gases though the flue pipe on your roof. How to vent a furnace in a roof 1.

You will now insert the long portion of your duct through the hole in the roof from below until it s about 24 above the roof shingles. That s because the combustion byproducts are in a gaseous form so the gases can float up through the flue pipe and out of your roof. If your furnace has an afue rating below 90 percent it will most likely have a flue pipe that goes up through your roof. This structure generally uses the furnace vent pipe through roofbecause the b venting pipe is designed in vertical manner.

Another problem is that flue pipes that go through the roof tend to be less efficient. Are you venting through a wall to the exterior for a horizontal termination or through the roof with a vertical termination. Also known as the type b this vent is operating on the natural air convection. When the vent is withdrawing air from the house it expels the gas outside through the vent.

High efficiency furnaces take advantage of the heat in the combustion gases that are wasted in natural ventilation systems. Run the vent pipe up through the roof and install a metal or pvc flashing collar over it. Push the male end of a new vent pipe up through the bottom of the roof flashing and set its female end on the male end of the vent pipe that connects to the gas furnace. Locate the spot to install the vent pipe using a tape measure to determine distance from a wall or other.

The vent pipe must overlap at each joint to prevent gas from leaking. That depends on whether you have a standard efficiency or a high efficiency furnace. Match the vent pipe to the. Should my furnace flue pipe go through the roof or the side of the house.

You ll want to know the thickness of your walls so you can properly prepare for your wall penetration if venting through an exterior wall to a horizontal termination. Vent your bath and kitchen exhaust fans through the roof through a special roof hood.