High Efficiency Gas Furnace Exhaust

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.

High efficiency gas furnace exhaust.

This residual liquid is highly acidic. 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. The flue gas exhaust temperature from a condensing furnace is fundamentally different than that of a conventional furnace. 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.

What is vented is a residual corrosive condensate of water and carbon dioxide. Gas furnaces burn natural gas to produce heat. Some products like furnaces may also be affected by installation orientation horizontal upflow or downflow or even by the nozzle used in installation as is the case with boilers and oil furnaces. 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.

If not installed correctly or checked regularly problems in these pipes can affect the operation of the furnace itself. Traditional gas fired forced air furnaces produce hot combustion exhaust gasses and therefore need metal vent pipes or chimneys. 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. Overall efficiency p efficiency within a model group will tend to vary by the size capacity of the unit.

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. A by product of this combustion process can be carbon monoxide a very dangerous exhaust gas. 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 a great majority of cases plastic piping is used to vent high efficiency equipment.

A conventional furnace vents these combustion gases through a vertical exhaust system that is attached to the furnace. 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. It is classified as type bh venting. A high efficiency condensing furnace can achieve efficiency ratings of 90 or above.