Noise reduction for portable generator?

[Harry Thornton]

Has anyone ever built an enclosure for a small (4000w) generator so that you can run it in a suburban neighborhood without driving everybody nuts? I was thinking a little wooden structure with louvred walls to direct the sound downward in four directions. Any other ideas? Improved muffler?

Also, is there a cheap natural gas adaptor for a 10hp Tecumseh engine? I have not done any research on this. I just wondered if this great source of engineering wisdom has already solved the problem.

[Bill Fields]

Harry-

Depends on your neighbors, really. If you bought the gen to take care of outages, the neighbors will appreciate your efforts with a "small wooden " structure. If you were running at lot and at all hours, the wooden stucture probably would disappoint.

HOWEVER--if your goal is attenuating the sound by a factor of 10--instead of perhaps 2--you should consider a cement block structure with air outs/inlets only facing your home. Engine mounts/lining of the interior walls, etc. are the many parameters that should be considered.

The exhaust noise is probably the easiest to deal with. There is a low-frequncy "thrumming" noise that is a sub-harmonic of the exhaust note.

Remember this:

"It is better to apologize, than to ask permission".

BILL FIELDS

[John Foote]

Try layers of dis-similar materials. Plywood, foam board, sheet lead, cardboard. Soaks up the vibes.

Bill Fields seems right. Most of the noise is mechanical. Get the hot exhaust outta there, as directly as possible, and focus on the mechanical noise.

Most important consideration is cooling that air cooled engine. Since heat wants to rise, let it work for you. Make sure to provide ample replacement air from underneath.

[Glenn Clabo]

When we lose power around here you hear the generators...I put a muffler extender on mine...but it's still loud. I've been thinking about converting to natural gas...but would probably go tri fuel. Try this place Harry. http://www.propane-generators.com/a-c_kits.htm

[Bill Lewis]

In this thread (http://www.sawmillcreek.org/showthread.php?t=22523), I commented on how quiet my Guardian Generac standby generator really is. None of this is accomplished with massive materials, but rather through isolation and baffling. Both the incoming air, and the exhaust are baffled. The baffle chambers are lined with a fiberglass type of sound absorbing material as well. The exhaust is mixed with the cooling air before exiting the enclosure. This cools it enough to allow it to exit through some louvers instead of having a tailpipe sticking out.
So I think it would be possible to make a doghouse type structure that could be quite an effective noise reduction enclosure. HD and TSC both sell the Generac's. You may want to go look at them for some ideas.

[Harry Thornton]

Thanks, Glen, I like the tri-fuel idea even though it costs nearly as much as the generator itself. There is also a wealth of information on noise attenuation. Hopefully I can come up with a good plan for a generator house that will reduce the noise enough that it doesn't drive me and my neighbors nuts.

[Jerry Bittner]

A few years back when we were confronted with an approaching hurricane, my wife's boss bought five of the 5000 watt with the 10 hp engine.

He arranged with a local mobile home dealer to take off the standard muffler and replace it with a muffler used on the generators for mobile homes.

Much quieter although not as quiet as a Honda muffler. You get what you pay for.