Hello
I've been doing some research about venting a high eff. Gas furnace and whether you need the air "IN" pipe as well as the exhaust pipe. Some installs are NOT running a pvc pipe for the air IN. They are relying on basement air. Is this OK or do you have to run a second pipe for fresh air IN? I would assume that fresh air would make the unit run better and safer. Is there any municipal laws stating anything on this topic? They did this install in my sisters home and want to know how to get the company to come back and run the air IN pipe outside.