I recently purchase a brand new home and have a question regarding the proper installation of my gas furnace exhaust plumbing.
The exhaust comes out the top of the furnace and along the basement ceiling out to the back of the house ( as well as the intake ). It runs about 15 ft. along the ceiling from the furnace until it clears a support beam, then goes straight up 1.5 ft. on a 45 degrees then goes another 10 ft. along the ceiling and out of the house. Should the slope or the angle of the exhaust plumbing run down away from the furnace slightly? Or, is level sufficient? The length of the exhaust is about 20-25 ft.
It seems to me that when condensation builds up in the exhaust it will roll back into the furnace. Here is why I think this....
Between the first elbow or 90 fitting that makes the exhaust level above the furnace (which seems too low) and the next elbow that brings it up around the support beam ( the 15 ft. run ) is not level, and in fact slopes slightly toward the furnace!! Not to mention again that after that it goes straight up! I have a bad feeling about this.
I move into the house in three weeks and have a Pre Delivery Inspection coming up. Can anyone who knows HVAC reply with some advice?