Limited Air Return with Garage Furnace
I’m thinking about buying a 1970s two-story colonial in the pacific northwest. It has a gas furnace located in a closet in the garage, right next to the door that leads into the house. The ductwork runs through a vented crawlspace to feed floor registers on the first floor, and a trunk line runs up to the second story (bedrooms) to feed floor registers on the second floor. I believe all of the ductwork is metal. I have no idea what the static pressure looks like.
There is only one air return, and it is probably at least slightly undersized. It is on the first floor, in the ceiling, right next to the door that leads into the garage (so the air return duct is quite short… probably no more than 6-8 feet from the vent in the house to the furnace in the garage).
Anybody able to speculate how big of a problem the single first-floor return would be for overall comfort, especially in the 2nd floor bedrooms? For a 1970s house, I’m not expecting perfection, and I know there would be a fair bit of temperature difference between the first and second stories. But I’m just curious if those more knowledgeable than me see stuff like this and think, “pretty standard for a 70s house, it would be fine,” or if they think “that’s something that would need to be fixed immediately.”
For the record, I don’t see any easy way to add an air return to the second floor. The expensive fix would be putting a separate system for the second floor in the attic (also vented, so not an ideal place), and replacing the first floor system with one sized for only the first floor. Small slim-duct style mini splits would be great. But to do 2 of them, including all new ductwork on the second floor, would probably be $30k or more where I live.
Thanks for any input!
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