Reducing Generator Noise

[knuckle Head]

This something I am concerned about in SHTF sitiation or for a standby generator and have read that others are concerned about this as well. So I started doing a little research and thought I would post what I found so far.

Let's what all we can come up with and help each other out on this issue.

<broken link removed>

Stealth Survival: Simple Survival Tips - Reducing Portable Generator Noise

Coleman Generator Sound Before and After Exhaust - YouTube

Read More

 

[ZA_Survivalist]

If I had a basement or quite possibly I could cut a hole in my floor where it would be placed technically in the crawlspace surrounded by drywall and tarp outside the drywall incase of any possible flooding (subpump would be off line in that point in time anyhow) with a few layers of eggshell foam or possibly egg cartons and cup holders from fast food places mounted on the drywall all around the generator, both dissipate sound well and if its in a contained semi structure already indoors and you were able to muffle and.vent out the exhaust via dryer vent tubing you could keep it very quiet that way.

 

[jbett98]

The biggest problem with air cooled engines, is how to dissipate the heat.
I once saw a 5000 watt generator stuffed into a large fireplace opening with a section of plywood covering the opening.
There was an 18" box fan attached to a hole cut into the plywood that was blowing room air into the fireplace.
The exhaust was piped upward into the flue and it seemed to work well.
The noise was considerable when standing in the room, but outside it was very diffused and hard to pinpoint where the sound was coming from.

 

[ATCclears]

Adding self to get updates on the thread...

 

[dolooper]

This is a great subject. My genset is not the quietest and it's going to attract attention. I've thought about what I can do about that. One thing I was thinking about was creating some sort of "box" for it using fiberglass insulation and plywood. It'd have to be a lot bigger than the genset as I'm especially concerned about adequate airflow around the engine, though there's no reason some of the output couldn't be powering a small fan.

 

[Both Eyes Open]

They make sound shields for marine applications. They cut the noise quite a bit but I don't think they would work for what is being discussed here. I knew a guy who lived off grid and he put his in a hole in the ground with an insulated cover over the top. Had a shorkel for intake and exhaust. He had a muffler of some sort that kept the noise down. All you could hear was a hum if it was running and you were inside his yurt. The genset was about 50' from the yurt. Just my thoughts. Good luck guys.

 

[chemist]

Like anyone in detection would tell you, it's not the noise, it's the S/N ratio. In a grid-down situation, it's likely to become very quiet most of the time - in between sporadic outbursts. If you really expect to run a gen 24/7, best of luck to you. In a truly still outdoor environment, you'd be able to hear the thumping of an internal-combustion engine from miles away. You don't need to pinpoint it to find it, if you just get a directional fix and start searching.

I'd hope to run mine for at most an hour at a time, and only during the busiest time of day - whatever that means.

 

[dolooper]

Like anyone in detection would tell you, it's not the noise, it's the S/N ratio. In a grid-down situation, it's likely to become very quiet most of the time - in between sporadic outbursts. If you really expect to run a gen 24/7, best of luck to you. In a truly still outdoor environment, you'd be able to hear the thumping of an internal-combustion engine from miles away. You don't need to pinpoint it to find it, if you just get a directional fix and start searching.

I'd hope to run mine for at most an hour at a time, and only during the busiest time of day - whatever that means.

Good points. As my goal is to keep food from thawing and pipes from freezing and to store up a little energy in batteries for nighttime use, I'd run only a few times a day as well and only when I'm around to keep an eye on the thing.

It's not just the disruption and attention in the neighborhood that drives that, it's the practical matter of fuel. I could run the thing 24 hours a day for 10 days if I could store 150 gallons of fuel, which practically at the moment is not going to happen. On the other hand, I can run it for a 4 hours a day for 10 days or 2 hours a day for 20 days fairly readily.

At the end of that, if there's not power restored or access to fuel, my thoughts will likely be about bigger issues.

 

[kibs45]

Portable generators are not really intended for this kind of use, ever. They are not made to be in enclosures. I am sure something can be made, but there are many variables, including how to vent heat off the air cooled engine like mentioned above. For a small portable unit where noise is of concern the only real option is the inverter style generators. They typically are around a 60db noise level under load. While quiet, it will stand out if its the only thing running, but the advantage is that it won't carry nearly as far. Biggest disadvantage is they are heavy for the amount of power, and they are expensive per kw.

A second consideration is all portable grade stuff is insufficient for constant use. A portable generator run for a week straight will pretty much be shot. An alternative option would be to purchase something like an RV generator. RV generators are typically more robust (especially if they are above minimum kw, roughly 5kw depending on make), and they are already in enclosures designed to limit sound. The disadvantage being that they are not readily mobile. And again, they are not being used for their designed purpose so there are issues to be worked around like fuel supply, etc.

Better yet would would be a fixed residential unit. Again, you need to be careful how robust the unit is. There are units that are residential only, and then there are units that have commercial counterparts, typically those are more robust. But they will all have sound limiting enclosures. Obviously though this totally removes portability from the equation. So you are not going to be bugging out with your generator.

Like anything else there are advantages and disadvantages to everything, so it depends on what you are planning for. Natural gas residential units are great if your power fails due to a windstorm a couple of times a year for a few hours, but, in case of an earthquake if the gas line goes, so does your power...

 

[mjbskwim]

I didn't go through the posts so if this is redundant,it wouldn't be the first time
Anyway,buy the nicest generator you can as it will be built better,with a smoother engine cough(honda)
Attach the big muffler as in the video
And either make a box with some 2" ridgid fome insulation,concrete,heavy timbers,or dig a hole and use cedar ,concrete or treated wood to line it.
You can place your generator any place you want,as long as nothing is touching the exhaust and the exhaust is sent outside,away from any windows and living spaces.And if it's gas,well all fuels,it should actually be in it's own enclosure/box that is vented to the outside.
But if you have it inside the garage and vented,nobody knows you have it. Run the exhaust outside,under ground and nobody knows different
And if you have big bucks,buy one of those sweet Caterpillar diesel gensets you see at the big car and boat shows.The ones you can't hear at all?

 

[kibs45]

I didn't go through the posts so if this is redundant,it wouldn't be the first time
Anyway,buy the nicest generator you can as it will be built better,with a smoother engine cough(honda)
Attach the big muffler as in the video
And either make a box with some 2" ridgid fome insulation,concrete,heavy timbers,or dig a hole and use cedar ,concrete or treated wood to line it.
You can place your generator any place you want,as long as nothing is touching the exhaust and the exhaust is sent outside,away from any windows and living spaces.And if it's gas,well all fuels,it should actually be in it's own enclosure/box that is vented to the outside.
But if you have it inside the garage and vented,nobody knows you have it. Run the exhaust outside,under ground and nobody knows different
And if you have big bucks,buy one of those sweet Caterpillar diesel gensets you see at the big car and boat shows.The ones you can't hear at all?

I can not stress enough how important proper venting is, and not just for exhaust and intake but for cooling purposes. I see lots of failures from improperly installed (read vented) generators. Like I said there are ways around it. A generator running in a garage but with exhaust and intake vented would probably be fine depending on installation, but again there are a ton of variables. Like I mentioned in somebody elses thread Honda powered units are good, but in the inverter line they have a belt driven overhead cam. It is not necessarily bad, but it is something to be considered for maintenance and reliability. It really does just depend on what an individuals need is...

 

[mjbskwim]

That is a point I missed.Air cooled engine would need some venting/air flow

 

[Cortes]

Extend the exhaust pipe into a steel 55 gallon drum of water. Drill lots of holes in the part of the sides of the pipe that is in the water. That will quiet the exhaust way down. No exhaust bark, just bubbles.

 

[dolooper]

I'm thinking about making something with this: NOISEPROOF YOUR LIFE® | Green Glue and particle board or plywood.

I'd need a "box" big enough for the unit and sufficient ventilation for the genset. Probably including ventilation holes as well and a small fan to run. I'm thinking the ventilation could reduce some of the sound if there's a gap and another "box wall" kind of like _-_ but with more overlap.

 

[bentbronco]

I think something like this would work for me Outdoor soundproof Enclosure for Portable Generator - YouTube

 

[rockitman]

Go to industrialaccoustics.com and poke around. You'll get some good info. While the materials you build the walls out of is important you still need to control the exhaust when it exits your enclosure. It will contain not only the fumes from your generator but the noise as well. For proper air flow you'll need the intake at floor level and the exhaust at ceiling level. Check with the manufacturer of your generator and they should be able to tell you the minimum cfm it will run on. You can then size the intake/exhaust with that info. At the exit/exhaust you will need to build/install a silencer (baffled box for the air to bounce around in). If done correctly it will be nearly whisper quiet. Good luck.

 

[mjbskwim]

I think something like this would work for me Outdoor soundproof Enclosure for Portable Generator - YouTube

That looks like a fire trap. The exhaust is too close to the plastic roof for one.
And he didn't do very good on the noise reduction.

Gunfix's link wouldn't come up for me but I'm sure there is some cool insulation on that site.

rockitman,as I was eluding to earlier,Caterpillar makes like 10kv gensets that are almost silent. Diesel generators mind you. Go check those out and see how they are built.
I've seen them at the boat shows where you had to walk to to the genset to hear it running.

It can be done.
But don't make it too hard to get to,so you don't forget to inspect it every once in a while

 

[dolooper]

That looks like a fire trap. The exhaust is too close to the plastic roof for one.
And he didn't do very good on the noise reduction.

Gunfix's link wouldn't come up for me but I'm sure there is some cool insulation on that site.

rockitman,as I was eluding to earlier,Caterpillar makes like 10kv gensets that are almost silent. Diesel generators mind you. Go check those out and see how they are built.
I've seen them at the boat shows where you had to walk to to the genset to hear it running.

It can be done.
But don't make it too hard to get to,so you don't forget to inspect it every once in a while

What the hell was I thinking? That wasn't the link I meant to post. This is the one: NOISEPROOF YOUR LIFE® | Green Glue

My unit is less than 30x30x30 so I'm thinking along the lines of half-sheets of plywood would be big enough to get some ventilation and perhaps doubling up with two sheets of sheet rock then a sheet of plywood on the outside with the accoustic adhesive between each leayer. . I could probably move it in pieces and keep it stored.

 

[OregonPlinker]

I know this is a little less advanced than you guys are thinking but when I run the generator for my camp trailer I just dig a hole, put the generator in it and throw a piece of plywood over the hole. Works fine. I learned it from my dad and uncle and they've been doing it since I can remember. Also my uncle has had the same generator since I was a little kid and my cousin has it now and uses it in this manor. It has never over heated... It does depend on where you are camping though. Sometimes it would take you the whole trip to get your hole dug depending on the ground. Then we just listen to the dang thing when we need it. Running the blender for margaritas and such...

 

[Cortes]

Running the blender for margaritas and such...

Have you considered an unblended margarita? With no salt?

1 oz lime juice
1 oz simple syrup
1 oz Cointreau or Gran Marnier
2 oz good tequila

Stir and pour it over the rocks. No generator needed.