Author Topic: Very loud apartment furnace  (Read 5017 times)


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Very loud apartment furnace
« on: January 04, 2012, 06:42:25 PM »

I've been looking at this site quite a bit for tips on how to deal with this problem.  Now I have some ideas, but I'd like to run those by the experts.

I have a very loud gas forced-air furnace.  It's in a closet in the middle of the apartment.  Most of the noise problem is airborne.  The only thing between the unit and the outside is a flimsy wooden folding door that's basically one huge vent.  So it blocks no noise at all.  The doorway is 6' wide, and unfortunately I think I can't seal it since I need to ensure there's enough air intake for combustion.

So my idea was to hang MLV curtains on both sides, where the inside curtain is sealed on three sides and open at the top a few inches, while the outside is the same except only open at the bottom.

Is this a good idea?  Will staggering the ventilation openings this way block sound that the curtains don't?  Will I need foam or something else to absorb instead of block sound?  I even thought of rigging up some sort of foam baffling in between the curtains.

Even reducing the sound the equivalent of an from open doorway to a cracked one would be a big improvement, but I'm serious about blocking as much as possible in that doorway.  I'll worry about whatever goes through the walls later.

Any feedback will be much appreciated!


Randy S

  • Guest
Re: Very loud apartment furnace
« Reply #1 on: January 06, 2012, 04:09:47 PM »
Nice "out of the box" thinking! your right on track...

So to simplify this, you are causing work load when air is in motion which will dictate value of reduction. In order to achieve reduction with out effecting the performance of your system you will need to do 2 things.
1) make sure the air space at each turn in the baffle is big enough to move the amount of air the unit needs..which might call for more 90* turns in the system...I normally start at 3 - 90* turns and add from there but you will see reduction each turn you add.
2) Yes you need absorption in the turn assembly, open cell foam will most likely work best in this design. Almost like filters at each gap through out the system.

You will reach diminishing point of return when you no longer focus at the gap when hearing the remaining will be reduced but not directly at the opening end of the baffle system.

Very Nice!  keep me posted please!  I would love to hear the results!