Handymen
Question: Clancy S. / Handyman (Madison, WI)
Every time my customer’s furnace turns on there’s a loud ‘woosh’ noise.
It’s so bad he has to find the remote and turn the TV volume up. As soon
as the furnace shuts off, the noise goes away and he has to turn the TV
down again. In the winter this can happen every couple of minutes. Here
are some pictures of the living room and furnace in the laundry room.
Help!
Sound-Answers.com
Your customer’s furnace is right on the other side of the living room
wall. There is a return air inlet back to the furnace in this very same
wall (white wall grille in the living room to the left of the
entertainment center). This is essentially a hole in the wall (covered
by a grille) right into the blower motor box under the furnace. You are
hearing the blower motor noise and associated air turbulence noise
directly through the return air grille. If you are qualified to do HVAC
repair, follow the instructions below. If not, consider contacting a
local heating & air conditioning contractor to fix the problem. One
option is Handyman Connection of Madison (866-578-2005) since the
solution may involve multiple trades. They have been in business for 10
years, warranty their work and provide free estimates. Provide the
following information to the contractor doing the work (if you don’t do
the work yourself).
- The existing return air inlet must be blocked off.
- Remove the existing return air grille in the living room wall.
- For an easier, lower cost solution, fill the hole with 1/2” thick plywood screwed to the wood studs. Seal the gap around the perimeter of the plywood with silicon caulk. This needs to be an airtight patch. For aesthetics, consider painting the plywood flat black (optional).
- Reinstall the existing return air grille.
- (Alternately for a higher cost and different aesthetic, you could consider repairing the wall with gypsum wall board, refinishing and painting the entire wall or room.)
- A new return air grille and duct must be installed.
- For an easier, lower cost solution, install a new, round, flexible duct in the unfinished laundry room. This type of duct will allow the blower motor noise to breakout into the laundry room as opposed to travel down an otherwise rigid metal duct into the living room.
- The new duct should be sized so that the air velocity does not exceed 400 fpm (feet per minute). Take air volume in CFM (cubic feet per minute) and divide by the air velocity of 400 fpm. This results in the required cross-sectional area of the new duct in square feet. The new duct should be at least seven feet long.
- Locate the new return air grille in the far right end of the same wall (opposite side of the entertainment center).
Beyond the question ~ While the round, flexible duct is cheaper, easier to find and easier to install, you may find that it is does not prevent washer/dryer noise from transmitting through the new grille. Consider using rigid metal duct with ½” thick internal duct lining instead if your customer will be doing laundry at the same time he is trying to relax and enjoy his living room.
