(From post re: furnace fan makes noise)
Until I figure out how to post a photo, let me describe the new configuration. Before the air intake was an insulated "box" that was 41" along one side and 59" along the other. (The indoor wall is angled.) It takes an 18x24 filter. The house is 1-story 1800 sq ft. The box protruded into the garage about 21"x21". The old much smaller furnace and coil sat on top of the box. Because of the size of the new unit, the installer dropped the unit down so the air intake box is now 20x38 because the last 21x21 section of the insulated box was removed to accommodate the new furnace. Before I didn't see the fan/blower because it sat on top of the box in the garage. All I saw was the insulated air intake box and I could see it made a 90 degree turn upwards. Now I'm looking right at the blower/fan because the installer cut an opening in the side of the furnace leaving the bottom intact. The remaining 20x38 air intake is still insulated but because of the proximity of the fan, the box is shorter and there is less overall insulation.
Originally, the owner said the box would need to be dropped down 10" which would have left the unit still sitting on the box but the installer said that wasn't enough room. The duct work above the coils is now 24".
The owner had a few solutions to quiet the whooshing sound. 1. Add a second air intake a short distance from the first so all the air didn't come in through one. 2. Add a second air intake in the master bedroom (which would help keep the temperature in there consistent with the living room area) plus another one in the hall ceiling or another bedroom. Both of these options require that an opening be cut on the other side of the furnace and duct work come down into the garage to attach to this new opening. These air intakes would have filters. The bedroom one would be 12x12 and the hall would be 12x18(?). 3. Make the original box larger. 4. Install a non-filtered return between the master bedroom and the current hall intake.
Would any or all of these options work? Which would be the best? Thanks so much!