How to quiet a Loud Furnace?

[keanhu89]

I have a small utility closet whith louvered doors which houses the hot water heater and the gas forced air furnace. My issue is that this closet is just off to the side of the living room and the return is one large vent facing directly into the room. When the furnace kicks on the sound of the motor, fan, and rushing air through the ducts is extremly loud and anoying. This issue is holding me up from upgrading the system to include central air. I could not immagine having to put up with this all year.

To help reduce the noise as much as possible I would like to insulate the walls in the closet, wrap the furnace and exposed duct whith insulation, and install a solid door. If possible maybe even duct the air return in from the attic. The previous owner has a 6' x 5' circular foil vent that runs into the attic. I think this should be sufficient for ventalation and pilot lights after I make the changes above.

Am I on the right track here or am i going to creeate a series of code violations?

Welcome all ideas and suggestions.

[Speedy Jim]

I would start by slowing the blower speed down.

Yes, there are issues concerning adequate heat transfer and overheating the furnace, etc. And possible problems with getting enough airflow over an evap coil with A/C. But that's where I would begin experimenting.

I have a hunch that you could put enormous effort into "soundproofing" the closet and still have the big "whoosh" sound.

Jim

[BobK207]

As per Speedy Jim's comment...

"I have a hunch that you could put enormous effort into "soundproofing" the closet and still have the big "whoosh" sound. "

your best return would be from reducing air flow speed (either by reducing fan speed or increasing louver / duct size)

IMO the soundproofing isn't going to give you much bang for your buck cuz' the open end of the duct (at the louver) will still be broadcasting the noise.

I have an old house where the previous owner had forced air installed to replace the original gravity system. The installers hacked into a bathroom cabinet to install a return air duct. I just recently re-did the job properly by finishing of the duct work & building a false bottom in the cabinet. I calc'd my "duct work" size & then tested my design by running the furnace periodically during the construction. I didn't want to build in wind tunnel noise to the system.

The result was no noisier or quieter than the existing installation.

If you want quieter, you need lower air velocities.

Try running it with the louvers removed....see if that gets you a noise level you can live with.

If not lower fan speed or bigger duct louvers. :(

cheers Bob

[Tony Hwang]

Hi, Lowering blower speed is upto a pint. If air moves too slow then you can voerheat burner not extracting heat enough. Typically when cooling blower runs at high, when heating blower runs at med. or med.-hi speed. Also filter is part of air flow.

[Joseph Meehan]

I suggest you start from the start. Get a pro in and have them run the "Manual" calculations. That will determine the BTU needed for heating and cooling and the duct sizes needed and they can also design a proper duct system. Right now it sounds like you have a builders special cheap system and it is not properly designed for your home.

I agree with the others that what you are thinking of is not going to help you much. I agree in general with what they are suggesting and I believe if you follow my suggestions above you will find that the result will include those suggestions. But remember heating and cooler are systems, not just ducts and furnace and AC. They all work together and they need to be designed for your specific home.

[samurai]

Is it possible to relocate the furnace upstairs on downstairs? It would be more appealing, and you may have more space to use off the living room.

Or change the cold air intakes to a different wall, to a different room, maybe a hall or something. May take some custom tin work, but it suprisingly not that expensive or hard.

If you go for the noise reduction, be sure to use good noise reduction insulation.

samurai.

[professorpaul]

I had exactly this same problem in a condo I owned once. Instead of having the fitting go directly into the room, I re-routed it inside the closet through about 6' of flexible hose. I did get a little pressure/flow drop, but not enough to present a problem. The noise level reduction was amazing. Before I did that, it sounded like a 747 in heat. I had to cut a hole in the side of the plennum, block up the old hole, etc. Parts at Lowes, and about an hour's work. Cost $50, maybe.

[Art]

Besides what everyone else has suggested, have the system start while you are looking at it. It could be a pipe is vibrating and giving off all the noise. That was the solution in our case. A piece of sponge to separate 2 pipes fixed the issue.