My house was built in 1962 and has 2 gas furnaces: a Goodman GMS90703BXA (69,000 BTU) for heating & cooling the south side, and a 1962 American Standard (100,000 BTU) for heat only for the north side. There's also a gas hot water tank. Oh, and two wood burning fireplaces (one in the basement and one on the main floor).

The Goodman is direct vented through the east basement wall into the back yard. The American Standard exhaust is through a stone chimney in the center of the house (combined with the gas hot water tank exhaust).

A fresh air duct runs from the east basement wall, between both furnaces and T's into their respective cold air return ducts, and then down to about 20" off the floor (I guess it's more of an X junction than a T...for hot water or basement fireplace combustion air?). It's 6" round duct wrapped with foil backed fiberglass insulation. It draws air from the back yard and is about 6.5 feet from the Goodman's exhaust/intake.

Now, I need to run a dryer exhaust out the east basement wall. I think when the Goodman furnace was installed (previous owner), they removed the existing dryer vent and used the opening in the concrete wall for the direct vent/intake. I suspect that this is the case because the pipes for that Goodman jog about 4 feet south from what would be a straight run from the furnace to the east a place where it would be logical to have a dryer vent (it's close to the dryer plug and washing machine water and drain hoses).

Also, if the Goodman were to vent straight out the east wall from the location of the furnace, it would probably be too close to the fresh air intake for code. You don't want those two things mixing up. As it is now, they're about 6.5 feet apart. A straight run would leave them about 3 feet apart...

So, I was thinking of having an HVAC contractor come in and route the existing fresh air duct through the north basement wall. The duct currently runs about 8 feet to the east wall, so this would involve a 90 degree turn and a total horizontal run of about 18 feet.

That would free up that east wall so I could move the Goodman vent to approximately where the fresh air vent was, and then put the dryer vent where the Goodman vent was. And when I replace the American Standard with a new high efficiency furnace, there should be adequate space to vent it along that wall as well (how much space is required between two furnace direct vents?).

I can't go south with the dryer vent - south lies a concrete wall to a crawlspace (with the main electrical panel affixed thereto), and another concrete wall to get outside from the crawlspace. Seems like a lot of drilling and complexity.

I don't know if it's some typical split-level architecture, but the basement ceilings are very high and it's concrete all the way up to the bottom of the floor above (to the top of the rafters). My old 2-story house had concrete to the bottom of the rafters and then wood rim joist and walls above.

Anyway, does any of this sound like a reasonable plan? Is there some other course of action that would be simpler? Thanks!