How should i seal hvac exhaust?
 

When we moved in, we had a new heater installed. It's a HE, direct vent unit and the installer vented it thru the side of the house using one of those combo vent/intake PVC pipes. He didn't weather seal it that I've noticed, at least from the inside. So I'm thinking caulk or spray foam where it passes thru the wood. Now the biggest question, do I need to use fire resistant caul or foam, since the exhaust and the intake are both on this pipe? I can grab some pics if you guys need them

caulk will work fine, seal inside and outside around the concentric vent.

Yep, caulk works great. Its very low temp(compared to 80% units having 325 plus temps), so no fire hazard under normal operating conditions.

Yea it's a York and its like a 97.8 or something like that.... Good to know, thanks you guys