Gas Furnace Venting Into Chimney

The exhaust system typically uses metal venting often routed into a chimney stack to exhaust the combustion gases created in the furnace fire chamber.

Gas furnace venting into chimney. Refer to figure 2. When venting two appliances separately into a common chimney always install the smaller flue pipe appliance with lowest gph input at a higher point into the chimney than the larger flue pipe for the appliance with the largest gph input. This structure generally uses the furnace vent pipe through roofbecause the b venting pipe is designed in vertical manner. For gas venting appliances the chimney flue venting rules are more complex simply because of the variety of products on the market.

The vent pipe must be firmly attached and sealed where it enters the chimney in order to prevent it from falling out to prevent air leaks into the chimney reducing the effective draft and to prevent flue gas leaks out of the chimney. For instance a 100 000 btu furnace venting into an interior chimney with a 38 square inch liner would not be allowed regardless of chimney height. The vent pipe or flue is a vital component of the furnace that transmits emissions from the combustion process out of the building. Furnaces that vent into chimneys can be hazardous but they don t have to be.

When the vent is withdrawing air from the house it expels the gas outside through the vent. To ensure proper venting however a liner must first be installed in the chimney. For many homes a gas furnace is the preferred heating device it has proven to be an efficient and reliable way of meeting household heating needs over the years. Also known as the type b this vent is operating on the natural air convection.

A conventional natural gas furnace will vent the dangerous combustion gases through a simple vertical exhaust system that is attached to the furnace. This chimney rule can be applied to wood burning fireplaces heating stoves and any oil fueled appliances but remember that manufacturer requirements have to be incorporated into it. This undermines the entire purpose of venting the furnace in the first place. The height of the chimney the area of the liner and the input of the appliance all play a role in the use of the chimney.

Taking care of the vent on your gas furnace is extremely important but working improperly and damaging your vent can have catastrophic results. A gas stove can be vented through an existing chimney whether it is a manufactured or masonry chimney. When the furnace exhausts into the chimney the gases quickly cool off before exiting to the outdoors. However using an interior chimney is extremely limited.

They can t all rise to the top of the chimney so some of them backdraft through the vent pipe itself and enter the home s crawlspace.