DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   HVAC (
-   -   Fresh Air Intake Location? (

AustinDIY 04-22-2008 10:55 PM

Fresh Air Intake Location?
I was inspecting my ducts for leakage and found something disturbing. My plenum is in a closet in the garage. Above my plenum closet (in the attic) there is a vent pipe for the furnace that makes its way out to the roof. Fine, looks good. Also, there is a metal pipe that creates an opening between the closet that houses the plenum and the attic. The plenum closet is also located opposite an interior wall where there is a grate for the return air. What is alarming is that the pipe to the attic (About a 8" pipe) is drawing attic air while the unit is running. I think this is intended to be how fresh air is introduced into the system, but shouldn't it be vented to the roof?

coolmen 04-26-2008 09:13 AM

could it be just for adding fresh air directly into the mechanical room for fresh air combustion for the 80% furnace. this setup would not be tyed directly to the duct it self. If it is connected directly to the RETURN side of the duct then they may added the 8" to bring in more return air as well as fresh air. yes the pipe should go to the out side. 8" is i think to big but dont no the size of the equipment. normally 6" is enough for fresh air but bring in to much just make the a/c work that much harder.

sgthvac 04-28-2008 04:32 PM


 I think this is intended to be how fresh air is introduced into the system, but shouldn't it be vented to the roof?

It sounds like combustion air for the furnace and no it does not have to be vented thru the roof. You should have some kind of vents in the roof and in your soffits to allow fresh air in the attic so it doesn't have to go thru the roof. Fresh air make-up for a home is another animal altogether and it is usually tied to your ductwork.

hvac122 05-01-2008 09:37 AM

As said above this is for combustion air. That is air for the furnace to breath while heating as flames need oxygen. Sounds like it is installed OK. Fresh air is something different. It would be tied to the return air to bring fresh air into your house. These are two seperate issues and can not be tied together.

All times are GMT -5. The time now is 05:09 PM.

User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.

Search Engine Friendly URLs by vBSEO 3.6.1