What appliances can be vented through a chimney liner?

Any appliances you have that burn fuel should be vented to the outside of your home. This can be done through a chimney liner, which is the material on the inside of your chimney flue that holds the products of combustion from your appliance until they are vented out the top of the chimney. Fuel burning appliances that must be vented include wood stoves, wood fireplace inserts, fireplaces, gas furnaces and furnaces, and gas water heaters. If you use gas in your kitchen for cooking, you should also have a fan-driven vent to collect cooking fumes and products of combustion from your stove burners for exhaust outside your home.

It is common for gas-powered appliances to be vented directly through a metal tube leading to a roof vent, but they can also be vented by piping the exhaust gases into a duct up the chimney. Exhaust gases from fuel burning appliances are corrosive due to the presence of water and carbon dioxide, along with other impurities, in the products of combustion, so it is essential that your chimney or vent pipe is made of a material that can withstand this acid environment. Older homes with brick or masonry chimneys often do not have linings inside the flues, but rely on the integrity of the bricks and lining (mortar) to prevent noxious gases and corrosive liquids from penetrating the walls. from the chimney and seep into the attached structure. Such chimneys should be inspected periodically. If damage is found due to corrosive gases, water, structural sedimentation, chimney fires, or other causes, you should repair your chimney and line the flues with a waterproof material to prevent further damage.

There are several materials that are commonly used to build fireplace surrounds. These include special mortar mixes, clay tiles, and metals, including stainless steel and aluminum. The type of chimney liner you should install depends on the type of appliance that will be venting into the flue. Clay tile liners or poured mortar liners are suitable for most fireplace applications. For appliances that run on natural gas or oil, a metal liner is best. Flexible aluminum liners are inexpensive, but should only be used with low-efficiency gas appliances. The exhaust gases from these appliances are hot enough to keep the evaporated combustion products out of the home, so their corrosive properties do not quickly damage aluminum siding. However, for a high-efficiency gas-fired furnace or other appliance, the chimney lining or vent pipe must be constructed of a special stainless steel alloy that is highly resistant to corrosion. The high efficiency of these appliances means that most of the heat generated by them is delivered to the house, rather than going up the chimney, so the flue gases are much cooler going up the ventilation system and, therefore, they are likely to condense on the siding surfaces. before they run out abroad. This constant corrosive exposure will wear away aluminum or masonry siding and greatly shorten its useful life. Many wood stoves and wood burning fireplaces are designed for use with stainless steel liners of the diameter specified by the manufacturer.