Pvc For Furnace Venting?

Inspected house with a older (approx. 20 years) Lenox Pulse furnace. There was a hole in the ceiling directly above the furnace that I presume use to be for a furnace vent. Given the age of the house I suspect this is the original furnace but I am perflexed about this PVC line…do you suppose this is now the new furnace vent? I did not think PVC could be used for venting?
Any help would be appreciated.
Hope the picture attaches…if not I will try again.

Thanks - Don

southgate 038.jpg

Hi Don,

PVC is common for vents on modern high efficiency furnaces, but would be very rare on one 20 years old, I would suggest that you check the installation specs on the manufacturers website.



Every Pulse furnace i have ever seen has had PVC venting. The 90’ and before models were known for heat exchanger problems and, i think Lennox was replacing them (the exchangers) due to the defect.

I’ve also seen several where the incoming line had been cut, apparently after the origional installation. Anytime i see these furnaces i recommend they be evaluated by a heating contractor and point the client in the direction of the wealth of information available on the internet.

Adam, A Plus

Lennox model numbers, that I am aware of, that have/had heat exchanger cracking problems are #'s G8, G9, G10, G11 and G12.

Also, the Lennox Pulse furnace, built before 1/1/1990, model G14 and GSR14 had heat exchanger cracking problems.

Thanks for the input guys…sure appreciate the help.

Regards - Don

Don -

Its rare to see anything but the approved PVC on a 90% plus Lennox Pulse furnace. Look in the books you received wherever you went to home inspection training school and I’m sure you’ll discover that you just overlooked this feature of your training.

The muffler on a pulse furnace is encased in PVC.

Everything and more you ever wanted to read on Lennox

at 97%, the lennox pulse is the most efficient furnace ever made. unfortunately it was complicated and some models were plagued by heat exchanger problems so it was discontinued. PVC is the proper vent material for this furnace