Originally Posted by Yamaha101
I have a ducane 90% furnace...My dad and his HVAC buddy installed it for me about 7 years ago. Question I have is that I was looking over it the other day and it has two 3" pvc pipes running out of it. I know the is for the exhaust and the other is for ???(fresh air). It has plenty of returns coming in. Question is do I need to leave this hooked up? It doesnt make too much sense to me that I am heating 15 degree outside air. Can I put a shutoff or something on it or better off to leave it alone.
The other 3" pipe is not fresh air, it is burner air and it has to be there for the burner to, Leave it be. Later Paul