I apologize in advance for lack of my knowledge about HVAC systems and sorry for the long posting. I am trying to provide as much information as I can.
This is my first home and I moved in to this home in February 07. It is about 3500 sqft home with 2000 sqft in the first floor and 1500 in the second floor. It has two HVAC systems. First floor unit is in the basement and the second floor unit is in the attic. The first floor has 12 air vents but only one cold air return in the hallway. The HVAC unit is right underneath the hallway in the basement. The cold air return is connected to the unit with a big circular shiny metal duct about 2 feet in diameter. This duct is about 15 feet long in total with two 90 degree bends.
The cold air return is exceptionally noisy. It sounds like a giant vaccum cleaner. The noise level is same with furnace(winter) and AC(summer). When it comes on, it is really scaring little kids if they are near the duct. Because this is a new house, builder is still attending some of the issues ( I have a basement leak. That is another story). But for the noise, he says that he followed the design specification and there is not much he can do to reduce the noise.
As far as the make and model is concerned, it is a Goodman. The furnace model number is GMH8. This is the only number I could find in the material that builder gave me during closing. I went to the unit and looked for model number for the blower but did not find any. The whole unit looks like a tower with three units stacked on top of each other. There is a little sticker on the middle unit with model number as CAPF4860C6AA with serial number next to it.
Sorry for not providing much information. I can call the installer to get more information if needed.
But as mentioned above, the noise is really unbearable. I am planning to talk to the builder's senior management to escalate the issue. But I doubt, if they are willing do anything to fix the problem.
Is there anything I can do to reduce the noise. I hired a building inspector before closing and he said that I can use automobile sound insulation tape inside the duct to reduce the noise. What do you think about this option.
Before closing, I raised this issue and they added insulation around the duct and told me they added a grid inside the duct to reduce the noise. Not sure where they added the grid but, it didn't help much.
Is there any specification on max allowed noise for home units. I can get a meter and measure the noise in db if required.
Thanks for reading this long posting. Any help is highly appreciated.