Basement ducts too low.

[flypants]

Hi there,

This should be a very easy question. I'm trying to finish one room in the basement, about 11' x 8'. The ceiling is about 6'9" - 6'10". There are 2 air ducts on the ceiling coming from the furnace. From the bottom of the duct to the floor measures 6'2" (my height). I would like to add at least 3" so I can stand up properly.

-The ducts measure 7" x 18" (126 square inches).
-I figure I can replace them with ducts which are 4" x 31.5" (126 square inches) so I can stand up in the room.

Then I can finish off the room by insulating/drywalling the ceiling, and covering or painting the vents that stick out.

I would like to know how much it would cost to replace and what is the best course of action.

Thanks :cheers:

[hvacvegas]

Hi there,

This should be a very easy question. I'm trying to finish one room in the basement, about 11' x 8'. The ceiling is about 6'9" - 6'10". There are 2 air ducts on the ceiling coming from the furnace. From the bottom of the duct to the floor measures 6'2" (my height). I would like to add at least 3" so I can stand up properly.

-The ducts measure 7" x 18" (126 square inches).
-I figure I can replace them with ducts which are 4" x 31.5" (126 square inches) so I can stand up in the room.

Then I can finish off the room by insulating/drywalling the ceiling, and covering or painting the vents that stick out.

I would like to know how much it would cost to replace and what is the best course of action.

Thanks :cheers:

Each piece of duct is going to have to be custom fabricated. Whenever it's custom, it gets reletively expensive.
Not to mention the special transistions, reconnecting the heat runs to the new duct.

I doubt you'll have good airflow.

You're gonna need to have a professional come out to look at the job, and give you an estimate.

There's to many open variables to even come close to giving you an estimate, not to mention we don't give pricing on this site at all.

[flypants]

Why wouldn't there be good airflow if the area is exactly the same

[beenthere]

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[beenthere]

Why wouldn't there be good airflow if the area is exactly the same

Because you don't actually have air flow in the corners of the duct. The less depth, the greater the area of no air flow becomes. Also, because you increase the surace area of the duct, which also increases the resistance to air flow. So hat a 4X32 duct becomes only able to handle the air flow of a 7X15 duct. Or roughly a loss of 150 CFM.

In reality, ist even more then that. A ductulator is for a ratio of 7:1 max. And 4X32 is more then 7:1, so you would lose more air flow then my ductulator says.

[skippedover]

beenthere is right on target. I've seen it done and the airflow goes to nothing. I'd recommend you consider moving the main trunk to one side of the basement where you don't normally walk. It's a complete re-do of the system but this is the time to have it done properly for even airflow. Especially if you're going to heat/cool the basement. I won't rail on about finished basements.