I need a sound barrier around my furnace.

[bczoom]

It looks like a rainy weekend so I'm back to finishing the basement.

I have an ele. forced air furnace but run the fan 24/7.

The kids "play room" buts up to the furnace area but the fan is a bit loud.

I have stick framed around the furnace and put 1" polyisocyanurate insulation between the studs but would like to make it quieter.

I plan on putting drywall over it which should help some. Should I replace the poly insulation with regular fiberglass?

Any ideas of material I could/should use to further deaden the noise?

Thanks
Brian

 

[beenthere]

A barrier works best if there is nothing 'solid' to carry the sound. A 2x4 stud will carry the sound. If a 6" wall is put up, but using staggered studs (every other one on one wall, the others on the other wall) then the insulation can be woven in between. This is the best. No air gaps as the sound will travel 'on the air'. (a closed door with a 1" gap at the bottom doesn't keep out much sound). Be sure that the sound doesn't go over the top, between the floor joists. Drywall is a pretty solid material and will act like a drum head, ie transmit some sound.
A soft wall material like ceiling tile on the inside walls and ceiling by the furnace will help stop the sound. Getting the fan off the floor, using rubber cushions will help dampen the sound created by the fan. If the fan is belt driven, then changing the pulleys to machined pulleys will cut out a lot of noise from belt vibration, and the link belts further dampen that sound. Running the fan slower rpm might help as well.
Just a few thoughts.

 

[hazmat]

Great advice from beenthere.

Also - you may want to use material specifically designed for sound deadening: a quick google search turned up this company b-quiet

Certain materials work better at certain frequencies so choose wisely /forums/images/graemlins/confused.gif- an acoustic engineer could explain it better...

 

[bczoom]

Thanks for the thoughts beenthere,

The area is already framed and I really can't change it due to space constraints.

The fan is inside the furnace. No belts or anything. The motor is directly connected.

Unfortunately (for me), I need a louvered area in the bottom of the wall because there is a cold air return right at the bottom of the plenum where it enters the furnace.

Sounds like I should replace the poly with either fiberglass, ceiling panels or some softer material.

Brian

 

[ByronBob]

My builder wasn't going to put insulation in my interior walls of my home. Asked him why and he said the only thing it did was help with noise barrier.

Took me 2 seconds to tell him to add all he could. Insulation is the way to go. Fiberglass style.

 

[bczoom]

Oh boy hazmat,

That professional stuff opens up a whole big can of worms. Too many options to try to figure out.

The google search led me to this page. That good stuff is pretty pricy. A 4.5x20' roll is $345 /forums/images/graemlins/shocked.gif

Looks like I'll take the soft material approach and put regular fiberglass insulation in like beenthere and ByronBob noted. I'm sure I have rolls laying around so it won't cost me anything to at least see what I can do with it.

If the kids are watching TV or whatever where they want it quieter, I think I'll just turn off the fan for that period.

Brian

 

[hazmat]

If you need a louvered opening for your return, don't waste your money on the fancy stuff - you'll still get noise thru the opening...

Maybe you should get this for your kids Inventor invents soundless sound system you can beam sound directly into their heads. /forums/images/graemlins/shocked.gif /forums/images/graemlins/cool.gif /forums/images/graemlins/confused.gif

 

[ultrarunner]

Neighbor had the same problem...turns out the HVAC contractor had the fan speed wired to max. (For air conditioning, which he did not have)

All it took was switching a pair of wires and now the fan noise is greatly reduced and is at the proper speed for heating

 

[PineRidge]

If your furnace uses a direct drive motor it's pretty simple to check with a volt meter to see which leads are powered under manual blower operation.

Most direct drive motors use black for high speed and red for low speed there may also be other colors like blue for an intermediate speed.

The white should be the neutral and you may have a pair of the same colored wires for a capacitor if used.

 

[bczoom]

My HVAC guy is my neighbor who owns a heating business. He and I have already gone through all the fan wiring and I'm pretty sure we have it set correctly.

I run the fan 24/7 to keep the heat from the wood stove circulated throughout the house in the winter and to keep the dampness out of the basement in the summer. I guess I can just turn it off when the kids are down there.

Hazmat - I did see that. Pretty neat. I like his helicopter too.