In a great majority of cases plastic piping is used to vent high efficiency equipment.
High efficiency furnace exhaust pipe.
Other aspects of high efficiency furnace venting.
If the flue is made of pvc pipe you have a high efficiency furnace also called a condensing 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.
If you are unsure if you have this style the big clue is in the venting.
New high efficiency furnaces can have efficiency of about 95 percent a huge savings for your wallet.
These pvc or cpvc pipes can be inviting to rodents and birds especially in the winter as well as insects mostly in summer looking for a home.
This high efficiency venting system must be installed when you install the new furnace.
It is classified as type bh venting.
High efficiency gas furnaces have plastic vent pipes that extend to the outdoors to get rid of exhaust gases and bring in fresh air for combustion.
Low flue gas temperatures allow for pvc flues instead of metal.
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.