Gas Furnace Venting Into Chimney

If any gaps remain and the vent isn t airtight the toxic gases will leak back into your home.

Gas furnace venting into chimney.

When the furnace exhausts into the chimney the gases quickly cool off before exiting to the outdoors. When the vent is withdrawing air from the house it expels the gas outside through the vent. However using an interior chimney is extremely limited. 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. 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. 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. 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.

Refer to figure 2. Furnaces that vent into chimneys can be hazardous but they don t have to be. To ensure proper venting however a liner must first be installed in the chimney. 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.

Taking care of the vent on your gas furnace is extremely important but working improperly and damaging your vent can have catastrophic results. To aid in removing the vent pipe a thimble or slip joint may be used. This structure generally uses the furnace vent pipe through roofbecause the b venting pipe is designed in vertical manner. 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.

For gas venting appliances the chimney flue venting rules are more complex simply because of the variety of products on the market. 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. A gas stove can be vented through an existing chimney whether it is a manufactured or masonry chimney. The area around the flue piping should be sealed where it enters the chimney.

The vent pipe or flue is a vital component of the furnace that transmits emissions from the combustion process out of the building.