Furnace venting 

Hello. I have a nordyne gas furnace and I can see one vent for sure going to the roof and I think the other one is what brings in Greg air. My pressure switch is stuck on and the troubleshooting said to check the venting for debris that might be clogging it. So should I try to get the tops off to see if there are leaves or something blocking the vents?

Did know you should have 2 vents for the boiler room

With a gas furnace running, during a drought, what would cause moisture to come back down through a vent pipe and puddle under the unit? (This vent is fed with a liner up through a chimney and connected to a vented gas chimney cap.)

do not cut a joist no matter what anyone says !!

So a furnace located in the attic doesn't require air from inside the house right? As long as the attic has side vents?

My gas furnace is currently venting to the old chimney & condensation keeps dripping down. Can I just vent the furnace through the side of house? Furnace is in utility room in back of slab ranch house.