Any good muffler kits for generators?

[Blackmagic71]

For several years now I have had a Duromax 5500 EH generator for emergency back up power at my house. Overall it’s been a good generator for a reasonable price.

The biggest problem is it’s very loud. Their website claims 69 db, but if I had to guess I’d say it’s at least in the 88-90 range, just at idle.

I run it once a month to keep the starter battery charged and move the oil around, so far I haven’t had any complaints from the neighbors, but it would sure be nice if it was at least 10 db quieter.

Does anybody know of any good muffler kits that would bolt up to it? I’d prefer not to have to weld anything because I don’t have easy access to a welder and my welding skills aren’t stellar.

[Trbo323]

Do you know what size the exhaust pipe is? That might be the easiest way. Find something like a moped or ATV muffler that's the same size, connect with house clamps.

You might need to swing by a muffler shop to have one of the pipes enlarged slightly to slip over the other

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[Blackmagic71]

Looks like it’s about 1”.

I wonder if this would work:

https://www.gopowersports.com/1-mini-muffler-w-hd-ss-clamp/?campaignid=15361704457&adgroupid=&adid=&gad_source=1&gbraid=0AAAAAD8hpWLrF4fUJW2dUdEg3XS1isL_v&gclid=EAIaIQobChMI_qa0tvvviAMV2TMIBR0AUwKUEAQYBSABEgItbPD_BwE

[Trbo323]

Might be worth a shot. Worst case is you are out $25

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[BLachance75]

I position my generator so that the exhaust points towards the back of the yard. Then I put a L shaped piece of plywood up with a moving blanket on the top. This directs the noise back away from my house and the side neighbors. I have a small patch of woods then an open area behind me so there isn’t anyone to bother back there. Of course this won’t work if you have neighbors on all sides of you.

It is surprising how much that little bit directs the noise. Even without the moving blanket on top it quiets it down enough that it isn’t too obnoxious. The blanket helps dampen and direct it a little more.

[Blackmagic71]

Unfortunately I’m on 1/5 acre lot in the middle of town, surrounded on all sides.

I did order that muffler tho. As Trbo323 pointed out worst case is I’m out $25.

[jetenginekyle]

Could build an enclosure for it, though that might be kinda pricey depending on how you do it. Would have the added benefit of protecting the gen.

[JeepDVLZ45]

Could build an enclosure for it, though that might be kinda pricey depending on how you do it. Would have the added benefit of protecting the gen.

I built an enclosure for my generator. It was pretty reasonable (the enclosure itself was the price of a nice used Phantom). I didn’t add insulation, but I did add an air intake to the shed as well as a fan/outlet to vent the heat (plug into the generator while it’s running) and a port for the exhaust. - that was another $100/$200 or so.

I extended the exhaust line about 2 ft, and point it away from the house. When it’s running, i can hear a slight “drone” from inside the house, but the TV or a fan running will drown it out.

All that said, I don’t live in a neighborhood so there are no houses to echo off and with the few times I need to use it per year. The sound is a small price to pay to be able to have heat and be able to flush my toilets.

plus my generator has a permanent home, it is completely out of the elements, easy to get to, and I have enough room to keep all my “generator stuff” with it.

[Tarsun2]

the enclosure is the way to go. keep all your stuff stored in there too.
thats what we did as well. keeps it out of the elements, keeps it organized, keeps it locked, and keeps it quiet...

[Blackmagic71]

Just an update: I added this small muffler extension today. It maybe lowered the sound level 1-2 decibels, but it’s still obnoxiously loud.

Might just plan on building a generator enclosure summer 2025.

Or maybe I’ll sell it on FB marketplace and pick up a quieter generator.

[flyweightnate]

I used to design a lot of enclosures for compressors. Three things to consider are airflow/ heat buildup (thus Jeep's fan hooked to the generator), line of sight (sound will escape through tiny cracks), and surface attenuation.

The easiest route is to place the generator on something that will absorb, not reflect, noise. Set it on a sheet of mineral wool or rigid fiberglass board, mark each foot, then cut out a brick-sized opening. Put the wool on the ground (preferably sealed into in a waterproof poly tarp) with bricks under each foot for support, and literally half the noise will be absorbed, instead of reflected off concrete.

Heavy vinyl curtains are a great, fast way to cut down on noise in a given direction. So is a wooden fence with a big air gap below to let a breeze through, but again, no line of sight to the generator, or anything hard the sound is bouncing off of.

High frequency will be attenuated by thin sheets of absorptive material (like carpet, fiberglass, etc) but as you go lower in frequency, the wavelength gets longer, so it needs thicker and heavier material to "soak" up the noise. 5kHz is a few cm... if your material is half the wavelength, you'll be in good shape.

https://www.omnicalculator.com/physics/sound-wavelength

The other advice here is all pretty good, too.