High efficiency or condensing furnaces exhaust the combustion gases and bring in fresh.
High efficiency gas furnace exhaust temperature.
Other aspects of high efficiency furnace venting.
There are several other important aspects of high efficiency furnace venting.
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 some high efficiency furnaces also include a plastic pipe for intake area and all types.
In high efficiency models the lower temperature of the exhaust can allow moisture a by product of combustion to condense in the flue especially when outdoor temperatures drop into the 20 s or below.
The pvc pipes are used for air intake exhaust gas and to remove the corrosive condensation resulting from the combustion process.
Whether the furnace is a standard a conventional furnace 50 70 mid efficiency 70 80 or a high efficiency furnace the provision for combustion air and flue gas vent systems is very important.
Vent pipe blocking the exhaust flow.