I’m doing a remodeling job in a 3 unit apartment building built in 1980. The builder used 12″ high open floor trusses between the floors. Each unit has it’s own heat/air unit with the air handler located in a louver door, centrally located closet. The units sit on a very simple rectangular cutout of the plywood subfloor. There are only two wall returns, one in the living room and one in a bedroom. The returns run down a stud space to a cutout in the subfloor also – so the return simply pulls air through the trussed floor into the units.
The Problem: the owner wants to blow insulation in between floors to cut down on noise, which would clog up the a/c returns. My idea was to close off all the returns and simply have the unit return through the louvered doors. The easiest way to do this would be to replace the lower service panel on the unit with a vented panel and install a filter on it.
The Question: does anyone make a vented panel for this purpose? The sides of the unit are too tight to get in to make a cutout on them. I’m not sure of the brand of the air handler but it’s very small and has two service panels (upper and lower).
Any ideas?
Nick
Replies
If these are fuel burning units and don't have isolated outside combustion air source I don't think that you can do this. The cold air return needs to separated from the combustion air to prevent back drafting.
Blowing in insulation will help a little with the noise, but not a lot. Noise will still transmit through the truss members.
A new layer of sheetrock mounted on resilent channel would reduce noise transmission as much or more than insulation and not effect the A/C air flow.
I'm not a HVAC guy. But using an entire floor plenum as ductwork is a bad idea, IMHO. Seems to me you're just asking for condensation problems, for starters.
Maybe one of the HVAC guys will have some more input...
If something doesn't feel right, you're not feeling the right thing
What is the heat source? If it is a combustion product, then don't use the door as the return. However, if the unit is a heat pump, then you could use some furring strips to hold slide in filters on the inside of the door. Weather strip the door including a good threshold, so that you get an air tight door. I would put in two pleated disposable filters, say 20x20, one high and the other low. Panel the non filtered area on inside of door. End result is a hi/lo air return with very little flow resistance, and great dust capture. Paul