[jclee]

The title should be "reducing air return size"

I'm doing some major remodeling. I am removing a load bearing wall that has a 6x24 return duct mounted on the wall on the ground. Since I will have an island overhang right above it in these new plans, I plan to save some work and not move the return air. It will just be converted to a floor register. Being under the island overhang, it will be aesthetically pleasing and will still function, but I want to reduce the size to make it less noticeable. Can I do that if I plan to cover up a couple of supply ducts. My thinking is that it will balance out the airflow. This is all in the main living space.

 

[beenthere]

Sounds like your about to mess up your system. Your gonna reduce total air flow, which can cause the A/C coil to freeze up when your using it, and also cause the furnace to trip on its high limit, and may damage the heat exchanger.

 

[dudleydoright]

where is the filter?

If the filter is located at the unit, why not use the kick space under the cabinets lower edge to create the return air grill and turn the void area under the cabinets into a plenum per se. If island is very big at all you should be able to incorperate adequate opening to equal the existing free air area. The only concern is for wiring in the area and making a good seal between the void and the base of the cabinets interior. Also floor would need to be well sealed. If duct entered center island, you could break up the openings. Normally a dark area, easily customized and out of sight. Would have to use plenum rated wiring or just run in emt through the island as required to isolate it from the air handling area.

 

[rydan]

Sounds like your about to mess up your system. Your gonna reduce total air flow, which can cause the A/C coil to freeze up when your using it, and also cause the furnace to trip on its high limit, and may damage the heat exchanger.

Absolutely correct... Way to much stress on your unit.

 

[dudleydoright]

also consider.

Another option would be to add a couple of induvidual return air ducts to rooms that are often not normally open, such as bedrooms. Separate return air ducts are much more efficient than a centrally located return anyway. Every time a door is closed and the furnace blower is operating it changes the system balance. It has been a point of contention lately that most systems are installed with an undersized return if sized according to the manual. Manufacturers agree on this and are in the process of redoing the math from what I understand. There are a few ways to accomplish what you desire, just need a little creativity. I have used kick space registers in bathrooms and kitchens many many times for supply, so there is no reason returns would not be just as effective. Are the cabs custom built or off the shelf fau wood? 6 by 24 is the same as 3 by 48 is the same as 2 by 72. Just need to equal the unobstructed free area of the register and a little over would not hurt a thing, as duct performance will be the limiting factor here. You could even specify a taller toe kick if cabs are custom built. It isnn't a deal breaker by any means, just take a bit of thought.