Air Return sounds like a jet plane taking off
Just had a new furnace installed...I think it is sized appropriately for the 2,000 suare feet house. Single stage, 70,000 BTU, - Carrier Comfort 80. I had a Carrier BTU 100,000 that this replaced.
The furnace is quiet, but the air whooshing through the air return sounds like a jet plane. The openning is 12 x 30. The installer bent the slats of the air return grille so they would be more open...but not much different.
this return is the only one and goes directly into the space under the furnace. the opening into the furnace is 25X14
Well, I'm guessing it requires 950 to 1050-CFM of airflow to keep the temp-rise within 60-F specs with 56,000-BTUH Output.
Where is the RA filter located?
To get it as quiet as possible I'd want 400-fpm velocity or less through the RA grille.
Hart & Cooley says a 24X24 grille will flow 1083-cfm at 400-fpm velocity.
Or, use a 30X18 grille that will flow 1016-CFM at 400-fpm velocity.
If U want a quieter RA grille, a 30X12 will normally only flow 674-CFM at 400-fpm velocity, it is too small... Hart & Cooley RA grille numbers.
The filter is at the bottom of the furnace, not at this RA grille. The 12x30 openning where the RA is located is framed in wood. My old furnace did not make this noise and this new furnace is smaller. (30,000 less btu). Same manufacturer - Carrier.
When I take the RA grill off, no noise. The air being sucked through the openning is much stronger than my last furnace.
So are you telling me that this openning that is framed with 2x4s with two additional vertical studs is too small? What do you suggest?
if your set up allows, add another return into the same return air plenum that feeds your air handler filter area.
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could have the blower set to high
I would wonder if the fan speed of the new furnace is set higher than that of the old furnace. In addition to adding a return, you could always have the RA grille replaced with a better one that allows more airflow. I'm assuming you have a cheap stamped face grille. They make commercial grade ones that are better designed to allow more airflow.