return air grill size

[froggywenta]

should not the opening size of the hole cut-out (covered by grill) be at least equal to or exceed the opening i/e size of filter or better for a home split a/c system?
thanks in advance
john

[Gunnery Sergeant Hartman]

If its a filter grill, we size them at 200 square inches of surface area per ton.

[faith]

Absolutely no way to provide a meaningful answer without knowing the volume (cfm) of conditioned air the return has to supply to stay within design specification.

How many tons of cooling capacity is the AC? What airflow is required through the evaporator coil to meet manufactures specifications?

What is the measured pressure drop across the filter?

Yellow Dot, are you stating that 200 square inches will furnish 400 cfm regardless of any other variables?

While square inches are often used to calculate makeup air for fossil fuel combustion equipment (Code Requirements) I would suggest a healthy and vigorous review of ACCA Manual D. One needs to analyze the entire system in total to understand what the effect of changes to any given point will be (in theory). Then the pressures (IWC) need to be evaluated at critical points to see if compounding factors have been overlooked.

Hope this helps… BTW: What has changed with your system to necessitate asking this question in the first place? I believe there may be another agenda lurking deeper within…

[dash]

frog,


Short answer,yes,it would normally be that way.

Blocked in some way,doesn't mean it's wrong with out ,as faith said,knowing at lot more about the entire duct system.

[Gunnery Sergeant Hartman]

Originally posted by faith
[
Yellow Dot, are you stating that 200 square inches will furnish 400 cfm regardless of any other variables?

[/B]

No I am not.
The question wasn't reguarding anything but return grill size...