High Efficiency Furnace Problems And Reviews

Question: How to vent a high efficiency furnace?

(Posted by: Skip A on 2006-10-21 08:14:03)

I had a new high effeciency (95 %) installed and want to make sure it's vented OK. The vent goes out the back of the house and extends about 6 feet beyond the wall and ends under the middle of ther deck. The pipe is pretty much level. Should the pipe slope down going out or up? Meaning should the moisture drain outside or back to the furnace? Is there any problem with the vent under the deck? At least there won't be any snow build up around the vent.

Posted by: Huero on 2006-10-21, 12:57:35

Normally the pipe is pitched so that moisture will run back to the furnace. It is not advisable to put more than a foot of PVC vent pipe beyond the wall because you may run into freezing problems. Also you cannot end the vent under a deck. Extend it out beyond the end of the deck about a foot. But you must also insulate the PVC pipe with 1 " thick insulation. You must not have had the job inspected by the local mechanical inspector because an install such as you have specified would not pass code. Good luck.

Posted by: Bonno on 2006-10-21, 08:44:47

THOSE REALLY HIGH EFF. MODELS USE PVC TO VENT OUT, IF THAT'S THE CASE, YOU SHOULD BE OK. IT SHOULD TILT DOWN SO NO WATER WILL RUN BACK TO FURNACE!

Posted by: optionnumber8 on 2006-10-21, 10:09:17

The vent should go down away from the furnace to drain the water away from it also the furnace should have a drain on it too to get rid of moisture from the burner or else it will rot it over time

Posted by: flashmp1 on 2006-10-21, 19:02:48

Installation instruction on most high90 plus furnaces use the low stack temperatures to help get the high efficiency up so high. they have 2 heat exchangers and and you slope 1/ 4 inch per foot TOWARDS THE FURNACE. the installation instructions will tell you hhow far out the wall you can go.. under a deck you MUST INSULATE THE PIPE SO IT DOESNT FREEZE. call the gas safety branch in your local area and get it inspected. good luck