High Efficiency Gas Furnace Exhaust

Venting for high efficiency gas furnaces materials due to the condensing nature of a high efficiency furnace its venting must be made of a material that is resistant to corrosion.

High efficiency gas furnace exhaust.

What is vented is a residual corrosive condensate of water and carbon dioxide. It uses a venting system to extract that heat before venting. A high efficiency condensing furnace can achieve efficiency ratings of 90 or above. In standard furnaces all these combustion gases including carbon monoxide are usually vented through chimneys or flues.

This condensing process along with the one that occurs within the high efficiency furnace itself creates moisture that can collect and freeze around and inside exhaust pipes since it can t travel far enough away from the home before condensing. A by product of this combustion process can be carbon monoxide a very dangerous exhaust gas. Condensing gas furnaces achieve their high levels of efficiency by adding another step to the fuel burning and venting process. It is classified as type bh venting.

The condensing furnace flue exhaust is relatively cool and can be vented with a plastic vent pipe without use of a metal chimney vent. In contrast modern high efficiency condensing furnaces exhaust much cooler gasses and need only plastic pipe materials such as pvc cpvc or abs for their exhaust vents. Gas furnaces burn natural gas to produce heat. When exhaust gases discharged from a high efficiency furnace exhaust vent meets the cold air the air condenses faster than conventional furnaces because it is cooler.

High efficiency or condensing furnaces exhaust the combustion gases and bring in fresh air through pvc pipes to the outside usually routed through the sidewall of the house. This residual liquid is highly acidic. Some high efficiency furnaces also include a plastic pipe for intake area and all types use a third plastic pipe to drain away the corrosive condensation resulting from the combustion process. In a great majority of cases plastic piping is used to vent high efficiency equipment.

The flue gas exhaust temperature from a condensing furnace is fundamentally different than that of a conventional furnace. A high efficiency furnace uses a different type of venting system because it extracts the heat that remains in those combustion gases before venting the resultant mixture of water and carbon dioxide. If not installed correctly or checked regularly problems in these pipes can affect the operation of the furnace itself. A conventional furnace vents these combustion gases through a vertical exhaust system that is attached to the furnace.