Genset soundproofing -- seeing light at the end of tunnel

I want to, first, thank everyone for your suggestions, even for the ones that I did not adopt. All of your ideas were valuable to me. I cannot literally think of even one post which did not have some bit of useful info or food for thought.

I am almost at the end of the work of making a generator enclosure and soundproofing it. I bought lead sheet and attached it to plywood panels. I need (and can) do a better job at sealing all holes and in fact on one side I have not even completed the enclosure.

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(I beg you to not xpost it to rec.woodworking)

I ran the generator today.

Despite this incompleteness, the enclosure appreciably reduces the noise. At 10 feet, with the access door open, the noise is 85 dB. With the access door closed, it is 79-80 dB. It also feels rather tolerable to be around this working genset. I would not mind it working all day long. It is much quieter than, say, my snowblower (87-89 dB).

Another good news is that, perhaps due to its weight as well as vibration isolation by two used tires, the enclosure basically does not vibrate.

I have hopes that when I am really done with this work -- have fewer and smaller and baffled gaps and openings etc -- I can slash 3 or so decibels from this, bringing noise down to sensible 76-77 dB.

The enclosure's panels are held by wingnuts and it is designed for very quick disassembly, because it is relatively heavy.

Plans:

  1. Finish the opening for cooling air intake and seal gaps better.

  1. Weatherproof the enclosure, I will use epoxy on top and oil based deck stain on the sides (to match the deck and shed nearby).

  2. Finish the electrical panel. I will make it based on a 12x24 1.5 mm thick aluminum sheet that I bought at Menards. The current electrical panel will be junked. The new one will have numerous gauges, a ON/OFF switch, and easy access to connect the power cable.

  1. Make a foundation from 2x2' patio blocks.

  2. Install the genset on it.

  1. Install transfer switch of some sort.

Thanks to all!

i
Reply to
Ignoramus9778
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I did some web research on paints once that may suggest you not use epoxy. Epoxy is tops at immersion resistance, ie., painting a bathtub. It has poor UV resistance, which implies rapid degradation outdoors. Suggest an outdoor polyurethane formulation, which also includes UV inhibitors.

Reply to
Robert Morein

I did a bunch of research on soundproofing some years ago and on seeing your pictures, I can tell you that you'll be able to drop the noise output quite a bit when you finish the enclosure. Sound is transmitted by moving air, so you want as few holes for air to escape the enclosure as possible.

Then again, running an engine in a closed box without ventilation isn't such a good thing. But there are ways around this as well...

Good luck. Sounds like you've got a solution you can live with and ultimately, that's what matters.

Reply to
Astro

Thanks. I have some experience with epoxy. It does seal as well as penetrate the wood. Even if the top layer deteriorates, the only thing that it will really affect is the tiny layer on top. Epoxy will still be sealing the wood. I used epoxy on some exposed parts (teak swim platform on my boat), they are outdoor 100% of time, and after almost

6 years, the platform is fine, save for some chalking of the top layer.

I am not making some sort of a beautiful yacht deck, so, I will be fine without UV inhibitors. All I want is that water does not get inside the enclosure. I also will cover it with tarp.

i
Reply to
Ignoramus9778

Thanks, I have similar hopes as well.

Well, the engine ventilates itself and exhausts warm air through a opening in the cover, which "ducted" to outside. The duct is visible on the first picture, I believe.

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I will apply some sound dampening substance to the duct and engine panels also. Maybe something as simple as electrical tape.

I agree. It is now becoming an acceptable situation, a generator that is weatherproofed and that is almost quiet enough.

i
Reply to
Ignoramus9778

I uploaded a few more pictures at

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Reply to
Ignoramus9778

I built my genset housing out of concrete blocks and a rebar reinforced slab for the roof, hand-poured. The inside walls are lined with 3/4" hard fiberglass ceiling tiles circa pre-1974. The enclosure is fireproof, weatherproof and nearly soundproof. Even the door is filled with concrete. To do items include externalizing the muffler system and forced-air cooling. But it's going on 20 years that the 'bunker' style enclosure has housed our generator and it's been maintenance-free. Of course, it's not as portable as yours (it's not portable at all in fact, but that deters theft). :-)

-- Best Regards,

Mark A. Weiss, P.E.

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Reply to
Mark & Mary Ann Weiss

That's interesting. How much access space do you have for repairs and maintenance?

i
Reply to
Ignoramus18155

You might like to do some searches on Outside Broadcast generator sets. There is a fair bit of stuff out there, including sound proofing boxes.

I recall some years ago standing beside a BBC 50kW diesel OB genset (on a fair size truck) that I could barely tell was running.

Looks like you are well on the way though.

Regards Ian

Reply to
Ian

Thanks Ian, I will look at this stuff out of curiosity, but, as you noted, I have advanced quite a bit. We are having some family issues right now, so I won't be able to do much on this in the next couple of days.

i
Reply to
Ignoramus18155

I have the same generator. In December I went out to check it out and found that mice had gotten into the electrical box and really made a mess. I have made most of the obvious repairs, but the breaker on the regulator trips as soon as the engine starts. Onan says to replace the card, but first I'll take it to work and let my techs look at it. Have you found any of these as parts machines?

Bob

Reply to
Bob

I remember some guy on smokstak.com who posted about a similar problem, but with a bigger Onan DJC. Was that you per chance?

Which one, the red one or the white one?

Is that instant or does it take a few seconds?

I had a similar problem that was fixed, largely thanks to invaluable help here on this newsgroup. In my instance, it was a broken low oil pressure switch that needed replacing.

Someone sold two badly broken Onans on ebay recently. You would probably salvage enough parts from them and almost make up your costs by selling the rest of good parts.

govliquidation.com is a site where you can buy military surplus onan generators, including civilian models, from time to time, direct from the military (10% of premium goes to govliquidation). I posted about several auctions recently.

i
Reply to
Ignoramus18155

I have a wooden platform that I place in front of the entrance to the blockhouse and I simply roll the genset out on to the platform to change oil, filters, etc. Works pretty well. Key importance is to have good fans pushing cool air from the outside in and through the blockhouse to cool the generator. Until I relocate the muffler system, I just open the door and the muffler is right there, so the exhaust goes right out.

-- Take care,

Mark & Mary Ann Weiss

VIDEO PRODUCTION ? FILM SCANNING ? DVD MASTERING ? AUDIO RESTORATION Hear my Kurzweil Creations at:

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sites at:
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Reply to
Mark & Mary Ann Weiss

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