||12-20-2010 02:26 PM
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.