cold air return whistles
I just had a HVAC company put new flex duct in the attic as ground duct work was all rooted out (under concrete. They used the 5 year old 5 ton AC Trane & 100K BTU Trane furnace and moved it up to the attic.
The cold air returns whistles a lot with just the furnace on especially on the 12 inch return line. To cold to turn on AC but I know when I turn on AC the blower runs faster and whistle will be louder.
They are going to come out and look but I want to know what to tell them I want done about it and not let them give me a song and dance story.
They put in 2 cold air returns. First run one is a 12 inch flex duct to one return grill. What size return grill should this have?
The second cold air run is a 16 inch flex duct to a junction box that split off into 4 separate runs and return grills. What size do the return grills need to be?