HE intake & Exhaust

I’m looking for feedback on any requirements regarding the discharge end and intake of pvc pipes at the exterior.

Do either require a screen? Are there any requirements regarding a tee or an elbow, etc. Also, I find several HE furnaces where there is no pipe connected to the intake. The furnace is using the basement air. Any thoughts on this?

Thank you in advance for your response.


I only tell my clients that it is a good idea to have a screen on them to prevent nesting during the summer.
Yes you can take air from the basement.
When I see this design I tell them about the intake for air and never put anything on top, I also mention that it is safer to bring in the air from outside and explain why.

Going to depend on what your local AHJ requires on intake most areas do not require a screen on intake but common sense prevails in a area with varmints.
If intake and exhaust penetrate the roof together the intake should have a 180 degree fitting to prevent intake drawing exhaust. The exhaust does not require a fitting because it has a drain hose connected within the furnace cabinet

No screen required just a good practice for low exterior. None for the roof penetration.

We have squirrels here that like to stuff pecans in any pipe opening on the roof that they can find. Once found a 3 inch plumbing vent on the roof blocked with pecans

Cool I have never run into this. I have found bird nests at the junctions on vent pipes. I have found nests for Hornets and Wasps also but never any Pecan nuts. LOL

Thank you for the feedback.