Oversized supply plenum

[RichR]

The supply plenum extends at least 6" on either side of the heating unit cabinet to accommodate a higher efficient

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39.14 KB a-coil. I don't see how the airflow will move across the entire coil. Is there a limit or ratio between the two?

[Marc]

Nothing in the codes or manufacturer's installation instructions that I'm aware of. This is something that is left to the contractor's common sense which some contractors do not have. I'd suggest that the restriction to airflow that is represented by the coil itself would be enough to redistribute the air flow adequately. Especially when it becomes slightly dirty. About the most that I could report is that I'd be suspicious as to whether or not the cooling coil is a proper btu/hr match for the blower on the furnace and for the outside condenser unit also.

Marc

[Terence McCann]

Are you saying that the furnace was an existing furnace and they installed a new A/C system and therefore the oversized plenum?

There may be spots on the evap that will see poor air flow/stratification and be prone to freeze.

The condensate line is wrong as well. I don't see a trap and it looks like it's way to close to the flu.

[plummen]

if the coil is bigger than the drive on the furnace your not gaining anything in my book anyway.

we often oversize the coil by 1/2 ton to gain some efficiency as long as its not bigger than the drive,but i match it to the width of the furnace