Gas Furnace Intake and Vent

[DMill40]

Hi, I have a Goodman gas furnace (with an AC above it). From all the literature on the furnace I read, the intake and vent (2 pipe system) can be 2" or 3" pvc depending on how far the pipe goes and turns. What I have installed are 4 inches (which reduce to 2 to connect to the furnace). Are those 4" pvc pipes okay to use or should i change it to 2" or 3"?

Thanks

 

[Breplum]

Wow, I've never seen 4" used. There is a chart to follow to calculate, based on distance and number of elbows.
too big should be fine, but kwazy.

 

[Sponsor]

 

[Fitter30]

If the flame is blue wouldn't worry about it. The 4" sweeping tee the capped end will fill up with condensate then spill back down just out the condensate like it supposed to.

 

[DMill40]

Thanks for the input! Glad to hear that it should be okay. The chart for the furnace says with 4 elbows the vent pipe at 2" can be 20ft and 3" can be 82ft, but doesn't address 4" or any oversizing (also doesn't say anything about the air intake sizing, or maybe I just missed it?). Also, I thought the cap was wrong too (but didn't think about it being filled with condense). Thought about just changing that elbow out, but reaming out a 4" pipe didn't seam easy, or if I changed out all the PVC to the termination point outside the house, I'd have large 4" holes that i would have to patch too.