harleysilo

the matter....

mudmixer

Are you talking about a furnace or do you also have a gas water heater?

What you do has nothing to do with a return duct. - That is a part of your air handling system. Fresh combustion air supplies are independant of the air handling system.

It is common to duct it directly to a furnace. An alternate is to duct it into a furnaca/utility room that can be isolated from the rest of the home.

harleysilo

air to condition in from outside...

glennjanie

Hey Harley:
The incoming air could come from the attic or through the attic to a down turn in a soffit, to the return air duct and could be a 3" PVC pipe. Just make sure it has some sort of screen on it to keep sparrows, rodents and insects out.
Glenn