Yesterday, I had a transfer switch installed to use with my emergency home generator. The generator was advertised, noise wise, as one with a lower decibel count than others. Not so. Yelling, and a lot of ‘what’s?’ ensued as I fired it up. Aside from the fact that I’ll be the only guy with power during a black out on my road (heh heh heh) I’d like to come up with something to deaden the noise. Could I build a dog house type of structure, and line it…with what? Any body try to do this? Any ideas? Oh, and it’s mobile…wheels and a pull handle.
I worked summers manufacturing enclosures for blowers, these giant industrial vaccum cleaner type things. They made an ungodly noise, so we made enclosures with a skin of aluminum around thick foam. They make foam specifically designed to absorb sound.
I’m thinking that I should have put this in IMHO.
Mods…feel free to move. Sorry. :wally
Egg cartons. Lots of them, at least a few layers.
Not sure if that’s a really good idea. I’m gonna bet that the prime mover is an air-cooled engine, and if you cause overheating, the engine longevity will possibly suffer.
I asked the same question here about six months ago, and it’s not easy. With a new “quiet” retrograde muffler, I was able to take a bunch of the “braaaaccckkkkk” out of it, but it’s still pretty noisy.
I remember that thread too. I think I advised you to install some supertrap mufflers. What did you end up with?
Itfire, I would recommend that you look for a small shed that comes in a kit that this generator would fit in. Homedepot and such places sell small sheds.
You will need to extend the air intake of the generator to an outside wall of the structure and you will also need to extend the exhaust out also. You could feasibly just extend the exhaust out and leave the intake alone but you may run into overheating of the motor. I’m probably going to do this with my generator next spring. I’ve got the shed and the generator, I just need to vent everything and then trench over to the house to get the electric across.
Once you’ve got the exhaust ducted outside the shed you can affix all manner of sound deadening devices to suit your needs. You’ll have to be creative.
A low resistance auto or truck muffler may work if you can make it not look ugly.
If you still want the thing to be portable after the install then you need to make sure that you use parts that can be removed. Flexible exhaust pipe might be an option too.
Yep, I did get one of the SuperTrap muffler kits from Jack’s Engines. Kinda pricy - just under $140 for the whole collection of parts. I did have to do some minor surgery to the generator - I cut the OEM muffler apart so I’d have the flange and a stub of pipe to mount the new one to, and had to do some cutting and re-working of the heat shield so the much larger new muffler would fit.
Naturally, there are no step-by-step instructions for this, so you’re entirely on your own, armed solely with whatever “Git-R-Done” mechanical aptitude you may have. There was a fair bit of fiddling involved - “If I cut this flange off the shield, and flip it sideways, I can attach it with this bolt to the frame over here, and if I cut a chunk of bar stock and bolt it to the shield, I can take off the gas tank and drill a hole in the frame and attach the other end there so the shield would flail around loose, then shim the tank mount up a bit so that bolt head won’t chafe a hole into the tank…”
Took me about three hours, including a trip to the hardware store for that chunk of bar stock. Don’t expect any great reduction of decibels, though. The new muffler left the generator quite loud, but it made a radical difference in the noise quality - much less grating and noxious.
Related thread:
Silencing a Generator
What is your generator mounted on? The noise could be attributed to vibration. In buildings almost all large machinery is mounted on dampeners that isolate it from the structure. These are essentially just springs.
I would say that building a structure around the generator woudn’t be much of a problem, provided you allowed enough air circulation. Plenty of air space and openings on opposite ends. The documentation might include the recommended airspace around the generator. If it’s not there, then ask the company that sold you the generator. They should know. Build your structure like you would build a house. 2x4s (wood not metal) and siding. And put lots of insulation inbetween the studs.
A more effective alternative (and more costly) structure would be some form of masonry. Mass is what keeps sound at bay, as opposed to air (for keeping temperature from penetrating). So a CMU (sorry cinder block) structure would work best. Depending on the height of the walls and how far away the generator is from the places you want quiet, you might not even need a roof. A lot of those concrete block walls around machinery don’t have a roof at all and they work very well. You would really be suprised how a 3 sided roofless concrete structure helps with the sound. Really this is the best method. 3 massive walls with no penetrations, no roof. The side with no wall will be noisy, but if you can aim it somewhere that won’t bother anyone then that shouldn’t be a problem. If you need to completely enclose the generator then no penetrations would be best. Use an window air conditioner to keep it cool. But all of this is probably waay too much for you. Sounds like you have a small generator. Doghouse would help. That’s what I would do. Lots of insulation.
Prolly not. I’m guessing he’s got anywhere from a 5500 to an 8000 watt gen.
Most, if not all of the noise is through the exhaust.
(My Generac is just flat out LOUD.)
Otherwise good advice though.
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- The best way to make sound shielding is to use stiff sheet metal (1/8" or so steel) and cover both sides of it with polyurethane foam spread a quarter- or half-inch thick. Thicker foam is better, but PU foam is not cheap. The metal has to be brazed or welded together, and polyurethane foam is sold in aerosol cans in hardware stores–it is used for filling/insulating small cracks and holes. DON’T bother trying to use wood or plastic, they will not work anywhere near as well as the metal would. That much new metal will cost quite a bit and it does not need to be in perfect condition, so I would go to a salvage yard and get some scrap. And 1/8" steel is rather thick to cut with a hand saw or a reciprocating saw–if you got no access to welding equipment, then mark where you want the metal cut and take it to the nearest dingy, dirty little muffler shop and ask the guy there if he will cut and weld it together for you for a few bucks. The entire seams don’t have to be closed up, it just needs to be joined every few inches. There is also another spray-foam insulation sold that is latex foam, it is non-flammable and non-toxic but don’t use it–it works like crap, it takes WAY longer to cure than PU and doesn’t bond as well. The foam kinda slumps so you can only cover two sides of the box at a time at the most, and you can’t put the foam on until after the steel is joined. The heat will burn the foam.
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- But as far as enclosing an engine, you would need a hose to run the exhaust directly out of any enclosure. I would probably try making the foam-box big enough to completely cover the generator, and have two “mouse-holes” , and run the exhaust out of one. The danger here is that the inside of the box might have heating rpoblems–so you might need a chimney in the top of the box, and run the exhaust out of that.
- But before I tried all that, I would probably just try hooking more mufflers or a bigger muffler on.
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