Construction material for portable generator sound-deadening box

[dmccarty]

I am thinking that direction too. Simply redirecting the sound, vs. enclosing the genny entirely, would help with the air flow and heat issues.

I was thinking the box served two purposes, sound deadening and hiding the generator. If the box was built so that it could be opened up when the genset was running that would help the heat issues. My first thought was to be be able to open the box so that the wall of the box towards the house was used to buffer the sound. The other four walls would be removed to allow air movement. The problem with that idea is its PITA to build and use, there still might be a hot spot on one side of the genset, a partial roof would help with the noise and rain but then you get back to heat build up again.

The more I look at alternatives to the power company the more I appreciate their service and price. :laughing::laughing::laughing:

Later,
Dan

 

[3930dave]

I am thinking that direction too. Simply redirecting the sound, vs. enclosing the genny entirely, would help with the air flow and heat issues.

From what I have read, putting a muffler on a generator isn't much worth the trouble, because so much of the generator's noise is from the motor itself, not the exhaust.

While it may appear somewhat arcane to most of us (me anyway, most of the time), proper acoustic engineering can accomplish quite a bit. The other thing I meant to mention was check out Generac standby enclosures - around here Home Depot used to have one mocked up in-store - a good friend of mine has one that runs on NatGas, it is impressively quiet, esp. with the lid closed.

Air cooled engines do tend to be inherently noisy - one of the reasons the original Bug was noisy for it's size. And... even as air-cooled engines go, not much engineering time goes into block-radiated noise with cheap genny engines.

That said, until you get to Honda, the "mufflers" on most small generators aren't much more than spark arrestors.

Design-wise, the cost/benefit goes something like "Cheap out on the spark arrestor - get sued by a major State when one of their Parks goes up in flames. Cheap out on a "muffler" - good luck to Joe Blow for suing us for hearing damage".

Dug back till I found the link I was talking about. Got a few details wrong (Gen type, etc.... ), but general concept was correct. Yes, you won't get Honda quiet with just a muffler, but the OP guesstimates 50% reduction and in the Comments one guy meaured "103 db of sound at the muffler of the original generator stock/ now 92 db noise at the muffler area of the modified generator currently" - using a similar bike muffler setup.

You have to read down, but the pictures don't make it clear that he is NOT supporting the weight of the new muffler with just the OE exhaust studs. He did fab up a relevant new support.

Joel's Garage: Quiet Generator Muffler

In looking back for that one today, I came across this one:

Quieten That Generator

Good history of what he did with mufflers. I like the welded flange + flex- hose approach, as it allows you to run the OE setup if you are in hurry or don't care about the noise, but allows the add-on muffler to be quickly attached. Obviously, fire safety would dictate appropriate attention/vigilance is needed when using an add-on like that.

Rgds, D.

 

[ray66v]

I tried everything. What finally worked really well is, I built a 30x40 barn around it.

I put it inside, open the back window, and close the door. Then, I can barely hear it.

 

[joshuabardwell]

Sorry, folks, but I may not have been clear that the solution, like the generator, must be portable. Although I would like a new barn...

 

[ultrarunner]

Uncle built a concrete bunker for his Genset 35 years ago and no problems... roof was also concrete.

Kind of resembled an a root cellar built into the hillside.

 

[PILOON]

I once ran a genset that had the pipe thread type of screw in muffler, (think it was a Tekcomish engine).I added 2 short lengths of pipe (like 6" + 8") and an elbow with the muffler screwed to the end.
I placed the genset on the ground and situated the muffler so that it was in a previously dug small hole in such a way that the muffler and exhaust was below ground surface.
This hole was perhaps the size of about a bit more than 1/2 of a 5 gal pail.
When that genset was running (from 8-10 ft away) all you could hear was the rattle sound of the valves, the earth absorbed all the exhaust noise!

 

[Midniteoyl]

Instead of stuffing it into a box, blow turn the noise away from the ears.. https://www.google.com/search?q=gen...g&biw=1283&bih=598&sei=DavTUYKYDcT_ygG-7IHwBA

 

[paulharvey]

I don't know if anyone as mentioned fiberglass duct board or even dense glass as possiblities. You could attach the duct board yo the side of aluminum street sign for weather resistance/structure. Neither is cheap unless you can scavange them up.

 

[Depmandog]

Even small engines greatly benefit (sound wise) from quiet mufflers. Case in point - we bought my son a 49cc scooter for cruising to campus (the idea gleaned after a summer vacation to Panama Beach - scoots everywhere - what a blast!!! ).

From the factory, this 49cc Honda clone's exhaust was quite and gutless. It had a difficult time toting around an offensive lineman. So I souped up the engine, including a performance (read loud) exhaust (ok, it's more like 80cc now )

Long story to say - check into a high quality muffler that won't degrade your performance, but lowers the db's at operating rpm. Small engines can be very loud or very quiet.

Another thought, check out the generator enclosure on a few motorhomes. They have already spent the time and effort to create an enclosure to accomplish everything you are trying to do. Why re-invent this wheel??

Good luck

 

[Danno1]

.


Hey, I just remembered. I was at an outdoor town spring festival type thing a few weeks ago and they had two gennies running. What they did was to surround them on 3 sides with hay bales. Worked pretty good.


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[CurlyDave]

No way that the quiet is worth the price of an eu2000 to me. If the box doesn't work, I'll just suck up the noise.

I know it is late in the thread, but I just had a thought.

I was in Home Depot today and saw a 100 foot, 10 gauge contractors' extension cord for ~$130. I have one that only cost $65 about two years ago. Look around and see what you can get. Putting the generator 100 feet away will quiet it a lot. Maybe add one piece of insulation board on the side toward you.

 

[dirt ditch]

Probably too much work and not portable. Army Revetment.

View attachment 328959

 

[MikeInEburg]

I don't know how portable you need the soundproofing to be... But I'd consider a tall topless box with one hole near the bottom for ventilation. It won't eliminate sound, but rather direct it skyward, where there is nothing for it to echo off. Put the ventilation hole away from where you'll be and maybe put a fan in it to force airflow.

 

[techman]

If you build a box for the gen, be careful that the unit does not regurgitate it's own cooling air. You need to have fresh air coming in and hot air going out, or else you can quickly overheat and destroy the unit. This, of course, poses a challenge since the openings for the air also let noise emanate. Unfortunately not quite as easy as "building a box".

paul

 

[BrandonR]

The best enclosures are power vented and have baffles, think of a muffler but for the entire unit. The champion inverter generators are quiet and less expensive than the honda.

Champion 1,700/2,000-Watt Recoil Start Gasoline Powered Portable Inverter Generator-73536i at The Home Depot

 

[kevinwak]

Before you even consider building a sound proof box you need to quiet the exhaust. The best soundproof box around will do nothing when the exhaust is still belching noise out the side of it. Add some kinda big muffler first and see how quiet it can get.
Around my area there are thousands of oil wells where the wellhead pump is powered by a 350 Chevy. The neighbors hated the noise. They now all have mufflers and then about 30' of flex exhaust pipe running off of the muffler into an oil drum that is half filled with water. Seems to quiet it a ton

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