Generator Resonator/Silencer

[3bcamper]

I have the 2.5 KW Onan propane generator hanging under my 2009 AI. I inquired with the local Onan dealer about putting a resonator/silencer on the exhaust of this generator. The cost seem reasonable but when I asked about actual benefits, i.e., how much will it really quiet the generator, he said it's marginal, as it is already a quiet unit. Does anyone have experience with installing these? Was it worth it?

[Protagonist]

Originally Posted by 3bcamper

I have the 2.5 KW Onan propane generator hanging under my 2009 AI. I inquired with the local Onan dealer about putting a resonator/silencer on the exhaust of this generator. The cost seem reasonable but when I asked about actual benefits, i.e., how much will it really quiet the generator, he said it's marginal, as it is already a quiet unit. Does anyone have experience with installing these? Was it worth it?

It's only quiet relative to other Onans. Relative to most other generators with the same output, it's LOUD!

The difference is about 3dB with the resonator vs without the resonator. Given that the decibel scale is logarithmic, that means it's half as loud with the resonator compared to without the resonator. That's hardly marginal!

I had Onan install a resonator on mine. But the service tech failed to install even one hanger for the now-heavier exhaust pipe, and the whole generator exhaust pipe fell off less than 5 miles from the Onan dealer! I took it back, and told them to reinstall it the right way— after nearly getting run over in traffic trying to retrieve it. They reinstalled the exhaust pipe, without the resonator that I paid for (which was damaged when another motorist ran over it before I could pick it up), with the result that my generator is now even louder than it was before they did anything.

Someday I'll get another resonator, and take it to someone who actually knows what they're doing for installation. I sure won't let the Onan dealer in Kenner, LA do it again!

[Kwils25]

I installed the resonator a couple of months ago. The generator is quieter now, but not dramatically. The best thing is it does eliminate the annoying raspy tone that can be heard from a fair distance. It’s well worth the cost.

Sorry to hear about your experience Protagonist. Next time just take it to a competent muffler shop!

[3bcamper]

Originally Posted by Kwils25

I installed the resonator a couple of months ago. The generator is quieter now, but not dramatically. The best thing about is it does eliminate the annoying raspy tone that can be heard from a fair distance. It’s well worth the cost.

Sorry to hear about your experience Protagonist. Next time just take it to a competent muffler shop!

So, any Midas can do this? What would I ask for there? The Onan guy knew just what I meant.

[Ryoungca]

I had it done a couple of weeks ago and the difference is noticeable. As Protag said it is still loud relative to those little Honda generators and the like. It also doesn't affect the vibration coming up through the floor but that's another matter.

[Protagonist]

Originally Posted by 3bcamper

So, any Midas can do this? What would I ask for there? The Onan guy knew just what I meant.

Try buying the resonator at Onan, and having it installed elsewhere.

[Kwils25]

It’s a very simple job that I did myself. Just buy the resonator and any muffler shop would be able to install it.

[busb2]

I bought the resonator on Amazon, along with one extra clamp. After a quick measurement, I simply used a hack saw to cut the existing pipe leaving room for the resonator and clamped it in place. It took about 15 min total to complete in my driveway. It is less annoying, and worth the time and small investment, but still makes to much noise standing close by or inside.

[Protagonist]

Originally Posted by busb2

I bought the resonator on Amazon, along with one extra clamp. After a quick measurement, I simply used a hack saw to cut the existing pipe leaving room for the resonator and clamped it in place. It took about 15 min total to complete in my driveway. It is less annoying, and worth the time and small investment, but still makes to much noise standing close by or inside.

In all fairness to Onan, even the quiet portable Honda and Yamaha generators would seem louder if you stood right next to them instead of at the opposite end of a shore power cord. But still not as loud as the Onan.

Here's a question for just about anybody with an Interstate: Exactly where does the generator exhaust pipe run? When those hopelessly inept service techs at Onan replaced my fallen-off exhaust pipe without the resonator, they ran it UNDER the generator to make the shorter pipe fit where the longer pipe used to be. Somehow I don't think that's the way it was originally.

[toskeysam]

Bought the Onan resonator....a “frog’s hair” mismatch in tubing diameters so it will not go in/on exhaust tubing. Crap! So much for a DIY installation.

[sheakev]

Originally Posted by Protagonist

Here's a question for just about anybody with an Interstate: Exactly where does the generator exhaust pipe run?

I can get a picture of mine tomorrow. I do plan on putting on the resonator to try to smooth out the sound. My daughter's big horse trailer (with a LQ) has a gasoline 4.0 Onan and it sounds less loud and harsh than the LPG 2.6 Onan.

[Ryoungca]

Protag: Here is a pic of the new shiny resonator and pipe going into the back left corner of the Onan enclosure. From there it makes an elbow up to the muffler. Hopefully you can make out enough details, it runs just behind the left mud flap (and is supported by a bracket just out of the picture on the left)

[Protagonist]

Originally Posted by Ryoungca

Protag: Here is a pic of the new shiny resonator and pipe going into the back left corner of the Onan enclosure. From there it makes an elbow up to the muffler. Hopefully you can make out enough details, it runs just behind the left mud flap (and is supported by a bracket just out of the picture on the left)

Weird. My Onan generator's exhaust pipe exits out the top right— not the bottom left— and then all the way across to exit behind the left mudflap.

[wachuko]

[wachuko]

Do not mind the circled area....just another photo of location of exhaust for generator

[Protagonist]

I wonder if Onan changed their generator enclosures— or their generators— between 2011 when mine was installed and 2017 when yours was. Because mine has an exhaust pipe every bit of 5 feet long coming out the top front right of the generator enclosure, not the bottom rear left.

[Al and Missy]

Quote Protagonist:
"...The difference is about 3dB with the resonator vs without the resonator. Given that the decibel scale is logarithmic, that means it's half as loud with the resonator compared to without the resonator. That's hardly marginal!...."

The resonator reduces the sound power by 3 db which is half the power, as Protagonist said, but the human ear has a non-linear response curve such that to be perceived as half as loud, the sound level must be reduced by 10 db. So "marginal" may well be an accurate description.

Al

[Protagonist]

Of course, once the generator has deafened you, it's all the same…

[jcsdra]

I just saw the new 2018 interstate that reportedly has a new improved generator muffler that also can work on prior models.

[Kwils25]

Originally Posted by toskeysam

Bought the Onan resonator....a “frog’s hair” mismatch in tubing diameters so it will not go in/on exhaust tubing. Crap! So much for a DIY installation.

On my 2014 AI I was able to fit the resonator onto the existing exhaust pipe. I did use a file to remove the existing paint on the pipe to be able to slide the resonator onto it. It was a good, snug fit.