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Generator Noise Control

4925 Views 20 Replies 17 Participants Last post by  VinsaHrdok
We're getting ready to get hit by the hurricane, so it's possible that I could be running my generator for a while. It's a 2.5KW Honda EM2500X, like the one in the picture. It's noisy. I'm looking for suggestions on building some sort of noise abatement enclosure. My thoughts are to put the generator on concrete pavers and build a box around it using treated 1/2" plywood and 2x4s. The inside would be lined with Rockwul for noise.

Do you have a design you could suggest? Ventilation and fire are obviously paramount concerns. The generator is 16" x 20". I'm not an experienced woodworker, so the design needs to be simple.

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Biggest concerns are ventilation and heat. I would check the back of the instruction manual for minimum clearances to combustibles. That will define the basic shape of your enclosure. The next issue to consider is how you are going to refuel and check the oil on your unit while it is running. You want to make sure you can gain access without too much trouble, especially if the weather isn't too nice. Maybe a lift up lid that you can shackle down so the wind can't catch hold of it?

For your first iteration, I would go for very simple construction, grab a 4x4 and a sheet of Ply or OSB. Put a 4x4 post inside each corner, and screw your sides onto them, but don't go all the way down to the bottom, Leave a couple of inches for air to enter the engine. On the 2 ends, don't go all the way to the top, leave an inch for heat to escape. Using 4 x 4's also gives you room to add your rock wool on the inside. (try to mount wool on the bottom of the lid as well) Have the top hinge with strap hinges and latch with a hasp. Slap a coat of paint on it to give it a little protection from the weather.

After you figure out everything that is a nuisance during this storm, you can redesign when you have the time.

Just be safe, don't have it too close to the house. Keep the spare gas in a separate location.
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largish and taller the better polystyrene box w/ an open top....
leave a couple of inches of air space at the bottom...
have open air space above the generator...
redirect the exhaust up w/ the largest dia EMT conduit sweep you can find...
aim the exhaust into one end of the sweep... don't fix the sweep to the muffler...
you want an air space between the sweep and the muffler so you don't create back pressures...
it's just a noise redirect... play w/ it's position for the best results...
plywood will resonate...
the polystrene is light and east to move to gain access to the generator...
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plan ''B''...
lidded plywood/OSB box w/ a thin Styrofoam lining open at one end...
aim the box where you want the noise to go...
don't forget your air space...
no need for a sweep here...
bigger boxes work better...
Based on my experience, even if you successfully reduce the sound on YOUR generator, you'll hearing all the other ones in the neighborhood. My next door neighbor has very large generator that sounds like a diesel 18 wheeler when it runs. With generators all around us it gets pretty noisy when the power goes out. :|
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Thanks for the input. At my last house, no one else in the neighborhood had a generator. There could be some in this new one.
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Any chance of rising water where you live? Better gab your materials quick because they will go fast.

What if...

Cut a 8 foot 4x4 into four pieces. Maybe anchor them into the ground about 6 inches or so. Build a simple frame around them with 2x4's and put a piece of plywood on top. Include a cross piece or two to support the weight of the generator. Make the whole thing 24 x 48. Or even 24x24 inches. Anchor the generator to the plywood deck with U bolts.

Typically the home centers carry plywood cut in 2x2 and/or 2x4 foot pieces. That would be just about right for your project. It would be about 18 inches above the ground.

Note: Build it upside down on the garage floor and then set it in place. I can draw a layout for you if you like. Just lemme know.

Others may have additional input, and all is welcome.

Good Luck. We'll be praying for ya.
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Just be safe, don't have it too close to the house. Keep the spare gas in a separate location.
Ah, generators. One of my favorites. I recall one apparently true story where a thief stole a running generator by moving a running lawnmower beside it, toting the generator away, leaving the running lawnmower. Apparently it took a little while before that was discovered. Good story, if nothing else.

Plenty of videos on utube on how to quiet generators. And I think most of them, if not all, are pretty much BS, and/or impracticable for a homeowner. Yes, they quieten them some. But when I see a before and after video, and a car muffler is used, and supposedly the sound goes down 10 or 20 decibles, but it sounds the same to me, I don't figure the time, money, and effort is worth it. But, they are sort of on the right track.

I was parked one day, in my vehicle, and one of those little motor scooters parked next to me. The thing was so quiet I didn't even know it was there until the guy had already shut it off, and was getting off of it. I was amazed. I think the mufflers act on different sound frequencies then car mufflers, or something, but definitely very quiet. So I checked on them. On craigslist there are a huge amount of used scooter mufflers available, for very low prices, around $4 and up. I have not had an opportunity to try one on something yet, but for the price think it is more than worthwhile trying one, maybe two in-line, and see how the sound is.

The idea of a sound deadening box is nice, but. There is the price of materials, figuring out just what you want, then building it. Security is needed, or it could well get stolen. And, probably issues if you wanted to relocate the whole structure. I've looked into the scooter mufflers a bit, and that is definitely where I would start. If it works, you are way ahead of the game, and if it doesn't work, you can still go the insulated box route with very little money loss. But your call. Let us know what you come up with.
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Just found this. Kind of funny and pathetic at the same time. The guy used a cherry bomb muffler, not at all noted for quietness, then goes on about it dropping 5 decibels, and how great that was. I believe that it was a kinda cheap Summit Racing muffler that was quietest in a comparison I read some years back. Anything but a cherry bomb. Might get some ideas from this.
What Stick said about the exhaust. That's your main culprit. A cheap solution would be 4 or 5" furnace duct pipe with an elbow at the bottom. Wrap the pipe with insulation. I would bet on about a 50% reduction but it may also deaden the most annoying frequencies.
I have one of these (without the dog) covering my generator. The I put some 1 1/2" pink foam board insulation on the 2 long sides. Quieted the noise down to a tolerable level. I stole one my wife's cookie sheets and leaned it over the muffler to redirect the heat. Red-neck but it works. We average about 7 multiple day outages a year, so the generator gets a workout.


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Mike, Noise should be your least concern. Run the generator long enough to keep your food refridgerated, 2 hrs on to keep food cold for up to 8 hrs if you keep the door closed. when you are running the generator you can access fridge to get the food you need, then close fridge and run long enough to re cool fridge. Protect the generator from water as best you can, and don't fuel it when it is running! Enclosing the generator can easily overheat the engine and cause vaper lock. Secure it with a chain and padlock. If You have a deck with enough clearance under it that is level, you might consider that a location to put it if you can tarp over it. If you remove a door lock you can fish wires into your house that way. use adequate sized extension cords for each item you intend to run to prevent ruining your fridge. Running electronics like tvs can get spikes from a generator that could damage expensive equipment. Use the circuit breaker on the generator to cut off power to your house before shutting off the engine to prevent the generators drop off in voltage as is winds down...And the same when re starting the generator, let it come to full rpm before turning the circuit on. Keep your fuel dry. I hope these tips will help you, and that you stay safe!
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Most of the noise comes from the exhaust. If you can extend the exhaust with larger pipe and direct it up above the house roof height you will significantly reduce the noise. An over sized muffler helps too. Some black iron or galvanized pipe and a large lawnmower muffler should be easy to find.

Since the generator is air cooled, you can't close it in with a box or it will overheat. A large piece of foam board insulation placed between the generator and the house but close to the generator will block the machine noise from the motor and generator very effectively, but will still allow plenty of cooling air to reach the motor and generator.

If you do both of the above, I doubt you will even know that the generator is running or not, until the lights go off when the generator runs out of gas.

Lost power last night about 9, didn't bother with the generator and it came back on around 2am. Just heard a transformer blow, out of power and working of the gen, need to get ready for winter I guess.
A Honda? Noisy? Must be defective....

Spent a lot of weekends at the dragstrip with my buddy and his son and the Honda's hardly made any noise at all. Of course, maybe they were smaller units than yours. My buddy used a Honda knock-off and it was noisy as heck. We just put a wall up between it and us and the difference was impressive. Of course, all we were doing was redirecting the sound, not making it quieter.
On that tall exhaust pipe, when not in use it would be an eyesore. I would set it up so I could take the tall portion down, then drop it back in place when needed. I'd also work out a way to mount a cover over it so rain can't fill the pipe. Maybe repurpose the cap on the gas water heater heat exhaust. The pipe is going to get hot. I would consider a steel tupe used for fencing, and I know there are simple fittings so you can drop the pipe in.

You could use some of that solid insulation (rock wool?) between house and generator. It is very sound absorbing. I'd wrap the outside of that block with plastic to keep it fairly dry. I also take it that the generator is elebated off the ground, and that the cage is easily covered on top, and secured to the ground since the cover and insulation will catch the wind.

Good information in this string. Out here in the desert, winds and cars crashing into poles, seem to cause the blackouts. But they seldom last an hour..
Welcome to the forum @couvish

For your information this thread stems back to 2017, and you may or may not receive a reply. Enjoy the forum.
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Basically all generators are noisy, and I wont suggest to cover it because its dangerous, but you can have a look inside the generator, maybe something inside makes it more noisy than usuar, maybe there is a broken piece and its floating in the engine, and its making the sound louder.
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