Venting Options for Furnace Replacements
Replacing your old furnace can be as exciting and as exhausting as replacing an old car — lots of new technologies to explore. Some of the new furnace features to consider are venting options. True, furnace venting may not exactly rev up your shopping engines, but good venting is essential to safe and healthful furnace operation and indoor air quality.
The conventional choice for furnace venting relies on the natural properties of heat energy and air pressure. Warmer and higher-pressure air transfers, moves, and rises above cooler and lower-pressure air. This simply means that hot gases from your furnace are going to naturally flow up your home’s flue stack.
Not so fast. With a natural venting option, a substantial pressure change can suddenly pull deadly flue gases back inside your home — back drafting. A vent upgrade may be in order.
The better venting option than natural vent is power vent. Power venting (also called induced draft) may use the same flue design as natural venting options, with one exception: there is a powered fan in the flue that pulls toxic gases through. It does not rely on natural venting. The fan starts pulling air through the flue before the furnace turns on.
The safest and most efficient venting option is direct venting. As the name indicates, direct venting conveys outside air to the furnace via a sealed pipe. A sealed second pipe — usually parallel to or encompassing the smaller supply pipe — conveys hot combustion gases from the furnace to the air outside your home. No ambient household air is used or affected by combustion.
Direct vent may be installed through a sidewall or the roof. Though, sidewall venting is more practical in many cases. If you are upgrading to a high-efficiency furnace, you will probably need to upgrade to direct venting.