Super Soundproofing Community Forum

Soundproofing Forum Topics => Soundproofing Generators, Pool pumps, Engine and Dyno rooms => Topic started by: Quinn Bean on May 26, 2004, 06:06:54 PM

Title: portable generator
Post by: Quinn Bean on May 26, 2004, 06:06:54 PM
I am RVer and I have a portable generator Generac  5000exl.  I get so tired of these other RVers bragging about their Honda  and Yamahi generators.   And that there is no hope for me to quiet mine down enough that I would be allowed in the Camp ground.  I sure would like to prove them all wrong.  And then splash all the RV forums with my solution.  This sure would put an end to all that crap they hand out.  I want and enclosurer that is light and portable, that needs ventlation.  I have seen your box but the demension look like they would be way too large to handle.  Looking forward to quieting their (other RVers) noise.
Title: Re: portable generator
Post by: Q. Bean on June 21, 2004, 06:11:25 PM
I now assume that nobody  else has this problem.  Or is it everyone is not going to speak up if they did.  Surley someone has a help.
Title: Re: portable generator
Post by: boborther on July 30, 2004, 11:37:07 PM
Quinn,



The box or enclosure can be constructed of lightweight materials such as aluminum  or a heat resistant plastic material. You would line the inside of the enclosure with a closed cell vinyl nitrile foam mat. Quinn, you will need to duct in ventilation into the enclosure, and also be able to duct the exhaust away from the camp site.

Quinn, this will take a small degree of set up, but when you are done, you can put the Honda  and the Yamaha campers to shame. It can be done , believe me.

Another method is the little box inside of the big box  method which might alleviate you from having to do the ducting of the ventilation or the exhaust if it is done properly.

This method would consist of 2 boxes one large than the other, you would cut out one side of each box and place th smaller box over top of the generator, and then slip the the large box with the same open end directly over top of the smalled box. You would line both box interiors with the closed cell foam. This method allows exhaust removal as well as ventilation into the generator.
The box diagram and muffler is at [url]http://soundproofing.org/infopages/generator.htm


Quinn, I sure hope this gives you a solid plan for quieting your outdoor generator. Thanks for the post.



Sincerely,



Skip

Super Soundproofing Senior Technical Advisor

Ph: (760) 752-3030    FAX: (760) 752-3040

Soundproofing Advisor to The New York Times

E-mail: skip@soundproofing.org

Anytime  (888) 942-7723

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Title: Re: portable generator
Post by: Dave Cook on February 25, 2005, 07:15:01 PM
I just read your post about quieting your generator.  I have the same problem (too noisy) and the same wish (be as quiet as a honda for a lot less money).

I am just wondering how you made out and what advice you could give me if any.

Thanks
Dave
Title: Re: portable generator
Post by: kurt a schmidt on August 12, 2005, 04:11:09 AM
i went to pep boys and picked up a car muffler that was compact enough to fit inside the generators frame,then i welded one end shut and drilled a hole in the side of the closed end and welded a pipe nipple(3/4npt)and welded a small flange that screwed to the generators exhaust port,the noise reduction was amazing!
Title: Re: portable generator
Post by: John Pearcy on August 17, 2005, 10:30:46 PM
I know there are a number of quiter generators on the market. Look for how many dB a generator is rated for in the specs.

We have one model that is rated at 65 to 67 dB and I have heard people say that it is reasonably quiet.

The models that are advertised as quiet tend to be more like 59 to 60 dB. We have some of those too, but are currently out of stock on our website.

Now, for making an existing unit quiet, be careful.

You have to make sure the unit gets air to burn.

You have to make sure the unit gets air to keep cool.

You have to make sure the unit can freely get rid of it's exhaust without causing, what do you call it, back pressure I think.

Don't simply put it in some closed box or shed. In a shed you can enter yourself, it can create a hazard, just like running a car in a closed garage.

Sincerely,
John Pearcy
-----------------------------------------
Sr. Engineer
Elim International, Inc.
298 Main Street. Suite 200
Buffalo, NY 14202
716-566-9500 x5870
http://www.eliminternational.com
http://www.eliminatorusa.com
Title: Re: portable generator
Post by: DonB on August 18, 2005, 05:08:22 AM
For a generator in an enclosure it's a simple matter to route your exhaust to the outside.  If you wrap your exhaust components with 2000° F. header tape, you will preserve the highest egt within the system enabling safe use of quieter and more restrictive exhaust components. This makes the addition of virtually unlimited lengths of tubing a non-issue. Insulating the exhaust greatly increases the velocity of the gas which reduces back pressure. This not only enables you to use the quietest of components without performance penalty or danger to the engine, it greatly reduces the ambient temperature and radiant heat within your enclosure. The wrap itself serves to further reduce noise.  This simple modification makes the entire installation safer, more efficient and enhances longevity of the equipment.
Title: Re: portable generator
Post by: jpearcy on August 19, 2005, 09:06:39 PM
DonB,

Wouldn't that add to backpressure to the engine? I know with vehicle engines that changing the muffler significantly can change the backpressure to the engine and creat a problem, but I don't understand it well enough to say how and why it causes a problem or how to correct it.

Sincerely,
John Pearcy
-----------------------------------------
Sr. Engineer
Elim International, Inc.
298 Main Street. Suite 200
Buffalo, NY 14202
716-566-9500 x5870
http://www.eliminternational.com
http://www.eliminatorusa.com
Title: Re: portable generator
Post by: DonB on August 21, 2005, 07:05:23 PM
John,

Insulating the exhaust preserves the heat of the gasses which greatly increases velocity. The increased velocity reduces back pressure. This compensates for the addition of more restrictive components.

Don
Title: Re: portable generator
Post by: jpearcy on August 24, 2005, 05:07:57 PM
Kurt, Don and others,

It is good information to know how to make your generator quieter.

I know a lot of people are very interested in being able to quiet down their generators. I'll be referring a number of them to this discussion.

Sincerely,
John Pearcy
-----------------------------------------
Sr. Engineer
Elim International, Inc.
298 Main Street. Suite 200
Buffalo, NY 14202
716-566-9500 x5870
http://www.eliminternational.com
http://www.eliminatorusa.com
Title: Re: portable generator
Post by: Ric B on August 25, 2005, 11:20:29 AM
Kurt,



What muffler did you get at PepBoys? Cost? Do you have any pics you'd care to post. I would love to keep the $800 Generac 4000XL that I bought which has great features, is HIGH quality, but is LOUD! If it doesn't work, I will buy a ELM-3000 or ELM-3600SS and do the same thing to it, since it will start out more quietly to begin with.  



Thanks in advance for your input and advice!

Ric
Title: Re: portable generator
Post by: DonB on August 26, 2005, 12:58:03 PM
Ric,

I also have a Generac 4000XL I bought in 1995 for around $800. Indeed, it is a very high quality unit. After all these years, I finally has to change the voltage regulator.

It's not very loud at all. In fact, it's a whisper  when compared to the 15 KW diesel genset I recently installed. I've been running this Generac on the front porch due to lack of a better protected place while running the wiring around the corner to the main panel. As long as we keep that front window closed, it has never bothered us. Is your muffler still okay?







Don
Title: Re: portable generator
Post by: rj on August 27, 2005, 04:13:14 AM
For those with a generac 4000 or 7000 exl, i did the double box with Mass loaded vinyl, long inlet and outlets, one with a big computer fan.

I have this unit...4000exl in my truck bed. Gas tank was removed from the frame and feed in elsehwere...

checked the temp with a meat thermo, it was well within what a would call good.

i took most of the good ideas and made them work....this unit is quieter then the china knock offs, honda's and all the rest.....

my cost? or about 80 dollars....and I can use this unit at home or where a please...I didn't want to honda ect for the rv only...is that right? I read they have to buy 2 units to do the job off one...

and believe me, they aren't quiet, I heard 2 of them buzz on enough ...over mine running...so it can be done!
Title: Re: portable generator
Post by: RJ on August 31, 2005, 01:34:07 AM
Update on how I got the exhaust out of the box....
http://www.grnet.com/therhinosuite/y2kandgenerato/photo-donvj's.htm
Title: Re: portable generator
Post by: Gary Hall on September 11, 2005, 02:52:50 PM
"i did the double box with Mass loaded vinyl, long inlet and outlets, one with a big computer fan. "

RC, do you have a picture / drawing of this box? I am interested in making one that will allow "easy" access. Each 15 to 24 hours I have open it up to stop/start and fill with gas.

O.K. to send pictures at the address below. I have 4 MBit down load and a 250 mailbox, send whatever you have.

Thanks.

Warm regards,

Gary

gary.chris at comcast.net
Title: Re: portable generator
Post by: rbarton on September 14, 2005, 02:53:34 PM
Don,



Yep, the muffler is fine. Only have a few hours on the genset. Still practically brand new. It is just too loud for those around us at campgrounds or even boondocking.



RJ,



Please post your box construction info. That sounds like what a few of us really want to do.  There is a huge group on RV.NET with a 120 page thread going back to the first of the year discussing this very thing and how to make decent gensets as quiet as the big $$$ Honda and Yamaha units.



Thanks!
Title: Re: portable generator
Post by: DonB on September 16, 2005, 05:42:09 PM
RJ,

I never bothered with much quieting for my 4000XL. All I did was was mount it to a ¾" plywood and 4x4 skid. I built a 3-sided box but that was mainly for weather protection during a hurricane and off-duty protection. This generator is not loud enough to be bothersome to us due to the construction of our home. I can't even hear the UPS truck pull into the driveway when working in my office right next to the drive. The noise certainly bothered no neighbors since the closest ones are ¼ mile away. I'm sure using it in a campground would be an entirely different story.

My diesel unit is a different animal. That puppy is loud. I built this thing a house. The bottom plate sits flush on concrete slab and is framed with full-cut 4x5 beams and sided with full-cut 1x6 heart pine barn boards and all the joints are caulked. I insulated it with R-13 and inside of that, I used aluminized sheathing. I routed the exhaust stack out of the building and 10' up where turns away from the house.  I wrapped the exhaust with header tape  to compensate for added back pressure and improve heat reduction. The ends of the house are ducted and baffled for airflow and the generator can be operated with the doors closed and locked. The fact that it's water-cooled with a high capacity engine fan allows for this. Air moves through the house like it's a wind tunnel. The roof is vented and baffled to allow heat to escape. These modifications reduced the sound level inside our house, and even on the proximate back porch,  from oppressively loud to virtually un-noticeable.

For a portable generator, I liked the ducted box design that was published at the supersoundproofing web site a while ago. That particular design seems to be missing now, having been replaced with a triple box design.  For portable camping usage, a ducted box would be great but this new triple box design would be difficult to deal with. Ultimately, it would be quieter but you'd have to be very conscious of heat. Generators don't do well with a lot of that.

I can email you pictures of my setup, if you're interested.

Don
Title: Re: portable generator
Post by: Krazyjohnny on September 17, 2005, 08:44:45 PM
I did the box inside a box thing last night using 3/4" thick foil backed foam board from Home depot.  This was just a test.  It did quiet things down a bit but no tthat much.  I think the foam board may be too rigid.  I then used some old carpet I had laying around and wrapped it around the generator and did the box in a box trick again.  Big difference!  I think the more absorbent of sound the insulator is the better.  I have a Power Pro 3500 form Pep Boys that I am using to power my RV and would like to get it as quiet as possible.
Title: Re: portable generator
Post by: Quinn Bean on October 10, 2005, 04:21:08 PM
I am just get back to this forum after a long time.  I sure would like to see those drawings and other imfo aabout the exhaust.  I am planing on doing the mods to the 4000exl next week. :-/
Title: Re: portable generator
Post by: Bill Joyce on October 22, 2005, 05:17:49 PM
I used a "sandwhich" of foam(looks like rubber) and composite.  It is simlar to material sold by WESTMARINE and BOATERSWORLD. I think I've reduced noise 20 to 30% but gets too hot. I
am now about to install a fan but don't know where to install it without compromising the noise reduction The engine end and front are the nosiest. Any idea wherelse I should place it. That I have to cut another opening in the box is disturbing.  Were I to do this again would use a db tester.

Actually  wouldn't do it again--would sell the Generac 4000xl for about 4400 and buy something else.  The hassle is too much for the results.

Having gone this far woould really ppreciate advice on fan placement. Are yo guys allowed to post your eail addresses and phone numbers?

Thanks, Bill
fb3824@webtv.net
253 686 1414
Title: Re: portable generator
Post by: Al Pfalzgraf on November 07, 2005, 06:57:38 PM
I've got a Generac 5500xl and am in the process of building a muffler based on this:
http://www.piteraq.dk/flight/muffler.html
It will be a while before the results are in.
Title: Re: portable generator
Post by: Hickory on December 27, 2005, 04:00:48 PM
The box diagram and muffler is at http://soundproofing.org/infopages/generator.htm

Hick
Title: Re: portable generator
Post by: Kerry Ianacone on February 16, 2006, 06:34:12 PM
i did the upgrade muffler for the 10 hp tecumseh engine (made by them, not aftermarket) on my coleman 6250 generator.  it made a decent improvement!  But the real difference, and this is going to kill you how easy and cheap it was, was my making a frame out of 3/4" PVC that was 8" wider and longer than the generator (about 12" taller) and drapped heavy blankets (the ones used to cover furniture during a move) around it.  it is ridiculous how well it worked!  no issues with overheating since the clerance all around it is adequate and the top is completely open.  One more thing, i added an albow to the exhaust so it vents straight up and not into the blanket.  If anyone is interested in pics or links to the blankets i boght from Ebay (6.5 lb heavy duty ones) just email me kerry.ianacone@adelphia.net
Title: Re: portable generator
Post by: Harry Roscoe on February 26, 2006, 06:30:15 AM
I saw your post on quieting your generator and wonder if you would be so kind to send me a picture.  Thanks

Harry
Title: Re: portable generator
Post by: Capp35 on April 03, 2006, 08:16:38 PM
Funny you say that.
When camping I just leave mine in the back of my Pickup (Dodge 2500), with the tailgate up.
Cuts the noise way down, for surronding campers. Noise can only go up.
Title: Re: portable generator
Post by: dumbazz on May 25, 2006, 03:59:07 AM
Using water tight flexible metal electric wire conduit you can route the exhaust into a larger muffler. I used 1" dia. and sleeved it with 1.5" conduit. My flexible exhaust
could be removed and installed as needed. I did have to cut the old muffler away from the mounting flange and exhaust tube. Brazing the conduit onto the tube and flange was no problem.

I also used insulated metal panels to line my generator compartment. These panels came from a metal door manufacturer. I would put my generator up against any in the campsite..... anytime.
Title: Re: portable generator
Post by: bulldozer on July 26, 2006, 03:46:39 PM
Quote
I now assume that nobody  else has this problem.  Or is it everyone is not going to speak up if they did.  Surley someone has a help.

Title: Re: portable generator
Post by: joel on September 27, 2006, 10:55:16 PM
hi bulldozer,



There's three pages of replies to Quinn Bean's 5/26/04 message on the Forum.  There is great info contained in almost all of them - check out the links and diagrams.  Just for drill, here's an updated link to check out http://www.soundproofing.org/infopages/generator.htm



Joel



Title: Re: portable generator
Post by: scooterbum on August 29, 2007, 04:44:37 AM
I bought a inexpensive gen at BJ's wholesale for $199.00 and it produces 3250 watts @ 68db....
I spent $15 at home depot for 3 2'x4' accoustic panels (ceiling type) and some duct tape.  Made a 3 sided box pointed at the river at camp and at 50' gen could not be heard....(with a little breeze)  Unfortunately these panels are basically made of paper...not good in the rain.

I am planning to build a foam box and fiberglass over it...and am looking for a high temp material to cover the inside of the exhaust end of the box.

any comments?....Suggestions?

Thanks, Brad
Title: Re: portable generator
Post by: mlp_deal on May 29, 2008, 12:07:47 AM
I wanted to add some more requirements to a portable generator box, dont want to hyjack the thread but think these are valid for this group...
I have a 3500W 6 1/2hp gasoline Genset to use camping. It is alledgedly rated at 68db (but I doubt it really meets that). I think that National Parks allow up to 72db but that is still too LOUD. I am cheap so the box needs to cost under $100 total, light weight and can be broken down for transport.  Only used 2 weeks a year (during summer for AC, dont need generator during winter) so materials can be cheaper.
I need comments/opinions on this:

A single box that is 24Hx30Wx36L (this gives about 3" of clearance all around)
Made out of 2" thick HVAC Ductboard ($50 for a 4x10 sheet).
Assemble with velcro
add a layer of accoustical tiles (cheap left overs from Lowes/HD)
4" dia cut outs on 2 opposite sides (for a 120mm computer fan). box around the openings so they are not straight thru (not sure how to explain this correctly)
wrap the whole thing in loaded vinyl OR 1/8" foam mat (moisture proof/resistant)
   
Title: Re: portable generator
Post by: joel on June 09, 2008, 10:03:39 PM
The small box within the big box, all interior surfaces lined with closed cell vinyl nitrile foam, gives ventilation air flow and still traps, absorbs and blocks sound.  Use the 'A' and 'C' boxes shown at   http://soundproofing.org/infopages/generator.htm 
And here is a link which discusses the closed cell foam to use (see first product listed)  http://www.soundproofing.org/sales/prices.html
Title: Re: portable generator
Post by: hawk49 on June 30, 2008, 06:11:52 PM
I quieted my Generac 4000 EXL quite a bit by adding OSB on both sides (full cover on cool side and half cover on muffler side, a full, hinged cover on the front and a 11 HP Kohler muffler (Part # 23755).  I welded a 1 1/4" steel tube from the original muffler and clamped the other end to the new Kohler muffler.
Title: Re: portable generator
Post by: jack2009 on May 04, 2009, 06:29:30 AM
Portable generators are useful when temporary or remote electric power is needed, but they also can be hazardous. The primary hazards to avoid when using a generator are carbon monoxide (CO) poisoning from the toxic engine exhaust, electric shock or electrocution, fire and burns.

Every year, people die in incidents related to portable generator use. Most of the incidents associated with portable generators reported to CPSC involve CO poisoning from generators used indoors or in partially-enclosed spaces.
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Title: Re: portable generator
Post by: Randy S on May 06, 2009, 07:15:01 PM
Yes, absolutely dont be inside the soundproof enclosure when the generator is running!...as for venting the exhaust make sure its leading to the outside or in a well ventilated area....
Title: Re: portable generator
Post by: joe0508 on May 28, 2010, 04:25:45 PM
i read the post about making a generator box cheap im just wondering how you routed the muffler and can you describe somehow better about what you meant about boxing around the cut outs
Title: Re: portable generator
Post by: joe0508 on May 29, 2010, 09:50:58 PM
what kind of acoustic tile did you use for that generator box my email is josephmoney5111@yahoo.com