Author Topic: Furnace noise and cold air return  (Read 44713 times)


  • Guest
Furnace noise and cold air return
« on: January 13, 2006, 04:08:17 AM »

Furnace in a raised platform about 30" high off the ground.  

Enclosed in a closet.  Drywalled interior.

Cold air intake (about 20" x 30") is at the wall under the furnace (i.e. through the raised platform through the wall) to a grill in the wall.  So vent distance from grill to actual furnace units is about 2-3 feet.


When furnace goes on, it is loud!

It is a mixture of the cold air running in, but also just the plain fan noise.


You need professional help!  Call on our toll free number: 888 942 7723  

BJ Nash

Dave Brown

  • Guest
Re: Furnace noise and cold air return
« Reply #1 on: March 08, 2006, 03:46:22 AM »
I have my own Heating/Cooling business and i see this alot especially in Condos.  Heres what you need to do to greatly help the situation :
1. Take off the return air grille to the return air box and line the entire inside box area (on each wall as well as top and bottom) with 1/2" Ductliner . Measure how much you need then go to a Sheetmetal Shop and buy the amount of 1/2" thick Ductliner that you need. You will also need an aerosol can of spray adhesive for the Ductliner. Ductliner will greatly dampen the sound of the furnace blower .  2. While your return air grille is off the wall, carefully bend open all the vanes so they are straight out ; this will greatly cut down on the whistling sound generated by the air making a 45 degree turn as it goes thru the vanes.  3. Have a professional place the furnace blower  on the lowest acceptable speed that will satisfy both heating and cooling modes of operation . Usually, the motor can be slowed without any adverse affect on the operation .

Hope that helps. Dave


  • Guest
Re: Furnace noise and cold air return
« Reply #2 on: September 28, 2006, 11:44:53 PM »
Hello pps,

Dave Brown's reply below is correct.  For the 1/2" thick duct liner he mentions the very best is our Super Soundproofing Mat - a closed cell vinyl nitrile acoustic foam.  It is available in 48" wide roll material and sold by the running foot.  For info and pricing see the first product listed in the chart at



  • Guest
Re: Furnace noise and cold air return
« Reply #3 on: November 11, 2011, 12:29:52 PM »
The foam you told about vinyl nitrile acoustic foam, where can i get it or what should i use to prepare it.


  • Guest
Re: Furnace noise and cold air return
« Reply #4 on: November 11, 2011, 03:38:40 PM »
Our SSP Foam Mat comes in different thicknesses - 1/8" to 2" and can be layered to make even thicker.  It will not burn and is approved for use in aircraft.  Normally applied with contact cement, we also have it with a peel off paper backing exposing a adhesive for quick and odor free application.

For furnace and aircon ducting, the 1" thick is normally used as the best balance of cost vs effectivity.

As always in dealing with insulation, sound or thermal, the key is "No Gaps"!

BJ Nash


  • Guest
Re: Furnace noise and cold air return
« Reply #5 on: December 08, 2013, 07:40:59 PM »
I actually have a question about the opposite.  I am wondering how to isolate the ductwork to the soundproof room from the rest of the house. Or is that even possible?