# 20 Kw Air cooled whole House Generator



## wildleg (Apr 12, 2009)

below ground, liquid cooled


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## Chris1971 (Dec 27, 2010)

wildleg said:


> below ground, liquid cooled


Not practical or cost effective for this application.


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## wildleg (Apr 12, 2009)

a lot of things aren't practical, until the job conditions, or legal constraints make them so. That is the point at which the customer needs to spend what is required, or get off the pot.


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## backstay (Feb 3, 2011)

Chris1971 said:


> Gave an estimate for a 20 kw air cooled whole house back up generator. The issue I'm having is with the city and the strict noise restrictions they have in place. 75 DB from 7 am to 10 pm which isn't an issue but the night time restriction of 55 DB from 10 pm to 7 am. These are smaller city lots with limited room for location. Has anyone built or seen any type of sound barrier for a whole house back up generator? Anyone have to deal with noise restrictions?


Maybe you should take jobs in "Greater" Minnesota.!


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## Chris1971 (Dec 27, 2010)

backstay said:


> Maybe you should take jobs in "Greater" Minnesota.!


I don't want to start a turf war with you.:laughing:


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## B4T (Feb 10, 2009)

Talk to Generac... you can't be the only guy with this problem... they might have a game plan already in place...


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## patmurphey (May 28, 2013)

The city needs to modify their restriction to allow higher decibels at night during a power outage. You should be able to make a compelling case that the town should not be in the position of banning state of the art standby generators. They should, at a minimum, allow zoning variances for the several common brands of standby generators.


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## Chris1971 (Dec 27, 2010)

patmurphey said:


> The city needs to modify their restriction to allow higher decibels at night during a power outage. You should be able to make a compelling case that the town should not be in the position of banning state of the art standby generators. They should, at a minimum, allow zoning variances for the several common brands of standby generators.


That would be great but, this city is about 250,000 population. I doubt I would make them change the noise ordinance.


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## Chris1971 (Dec 27, 2010)

B4T said:


> Talk to Generac... you can't be the only guy with this problem... they might have a game plan already in place...


I plan on talking to Kohler and Generac to see if they have any options available. Thanks for the info moderator B4T.....:laughing::laughing:


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## HackWork (Oct 2, 2009)

B4T said:


> Talk to Generac... you can't be the only guy with this problem... they might have a game plan already in place...


There's really not much that can be done for a 3,600RPM generator.

You can install a muffler that will probably decrease the power output, but it would still be loud. You can put it into an enclosure such as an insulated shed, but I don't believe Generac will allow that. The shed with proper intake and exhaust would cost more than the generator.

I think the best bet is to put the generator in the far back corner of the property behind something so that the sound doesn't hit the neighbor's house.


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## BytheBook (May 29, 2013)

We had a problem with the sound in a small village. What we did is basically installed a parabolic reflector on ground around the generator on hinges (to service). It reflected most of sound upwards


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## svh19044 (Jul 1, 2008)

We have had to get variances for generators in a couple of gated communities. They didn't want anything over 60db but allowed the variance for up to 66dB for a stand-by generator.

There were also size ordinances and I'm not sure any kind of "enclosure" would have been permitted.


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## patmurphey (May 28, 2013)

Chris1971 said:


> That would be great but, this city is about 250,000 population. I doubt I would make them change the noise ordinance.


Can't lose by trying. Your city does have representative government and maybe a local paper? With a city that size you should have plenty of allies to get a modification of the rule or reasonable approval for a variance. I can't believe that the noise regulation was meant to deprive residents of standby power during a general outage. Your neighbor sure wouldn't be unhappy that you have an external plug on that 20kw genset.


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## svh19044 (Jul 1, 2008)

patmurphey said:


> Can't lose by trying. Your city does have representative government and maybe a local paper? With a city that size you should have plenty of allies to get a modification of the rule or reasonable approval for a variance. I can't believe that the noise regulation was meant to deprive residents of standby power during a general outage. Your neighbor sure wouldn't be unhappy that you have an external plug on that 20kw genset.


Exactly. And not only that, but the weekly test functions would be at day during the louder noise restriction. The generator would literally only be outside of the ordinance when standby power was necessary.


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## Bugz11B (May 12, 2013)

Kohler and Cummins both for sure have generators that are compliant (20kw is smaller then I have installed at houses and we meet the strict noise restriction requirements), Im sure other manufacturers also have compliant generators, I dont know exact models (I dont make the orders) but your distributor should have no problem getting you squared away.


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## HackWork (Oct 2, 2009)

Erik.Schaeffer said:


> Kohler and Cummins both for sure have generators that are compliant (20kw is smaller then I have installed at houses and we meet the strict noise restriction requirements), Im sure other manufacturers also have compliant generators, I dont know exact models (I dont make the orders) but your distributor should have no problem getting you squared away.


Generac does too, but he is looking for 20KW air cooled.


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## kbsparky (Sep 20, 2007)

Generacs operate at half-speed for the exercise period, 12 minutes or so per week.

Betcha that would be compliant ... a lot less noise than those noisy lawnmowers, weed whackers, and leaf blowers ....


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## patmurphey (May 28, 2013)

The issue is not exercise decibels. Almost any generator will meet the 75 db limit from 7 AM to 10 PM. It's the 55 db rule from 10 PM to 7 AM - that would only be exceeded during a power outage. There are no typical home sized generators that are lower than the low 60's db, including the so called "quiet" generators. If the town measures db's closer than the typical published standard distance, the issue is worse. The cities/towns with these night time standards need to reasonably allow standby generator use WHEN power is out.


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## Bbsound (Dec 16, 2011)

Where is the SPL measurement taken by the city? At the property line?
How far away is the property line?

Tell the zoning asses that it has a built in timer to shut off at 10 pm.


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## Bbsound (Dec 16, 2011)

http://sengpielaudio.com/calculator-distancelaw.htm


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## doublejelectric (Jan 23, 2013)

Chris1971 said:


> Gave an estimate for a 20 kw air cooled whole house back up generator. The issue I'm having is with the city and the strict noise restrictions they have in place. 75 DB from 7 am to 10 pm which isn't an issue but the night time restriction of 55 DB from 10 pm to 7 am. These are smaller city lots with limited room for location. Has anyone built or seen any type of sound barrier for a whole house back up generator? Anyone have to deal with noise restrictions?


I'm curious what your number was for this, I just quoted the same thing here in california. But, had to sub a plumber for 250' of pipe. Owner crapped a chicken when he got my price.


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## oliquir (Jan 13, 2011)

a crazy setup would be battery backup + inverter for night and they are recharged by generator on day !


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## Going_Commando (Oct 1, 2011)

Bbsound said:


> Where is the SPL measurement taken by the city? At the property line?
> How far away is the property line?
> 
> Tell the zoning asses that it has a built in timer to shut off at 10 pm.


Heck, sell them a Tork timeclock so if the inspector looks he sees a timer, and then run some wire over to the transfer switch, have it go to a terminal block, and have some other wires running elsewhere and say they go to a generator but have them end in a fixture box or something. :laughing::whistling2:


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## Cow (Jan 16, 2008)

Does the city do a decibel check at inspection time? Or require a cutsheet from Generac with the decibel levels listed?

If not I'd be inclined to find the quietest generator I could, inform the customer of the situation, and then let them make the decision. They might be willing to take their chances the few times they need to run it after hours.


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## wildleg (Apr 12, 2009)

Cow said:


> Does the city do a decibel check at inspection time? Or require a cutsheet from Generac with the decibel levels listed?
> 
> If not I'd be inclined to find the quietest generator I could, inform the customer of the situation, and then let them make the decision. They might be willing to take their chances the few times they need to run it after hours.


the problem is three fold:
1) getting paid
2) getting sued
3) getting a red tag

1) & 2) when you sell something, you are selling it under the legal auspices of the product being "suitable for its intended use". If the customer can't legally use the item, then you are at fault for selling something that is useless. This opens you up to either not getting paid, and/or losing the suit, or getting sued later. (implied warranty: http://www.law.cornell.edu/ucc/2/2-315) In addition, many jurisdictions have specific laws protecting homeowners from people selling them stuff that doesn't work, or doesn't have a warranty, and if you somehow write a contract selling them "as-is", your contract may not be legal.

3) I guess this goes without saying, but those little black marks can eventually add up on your license in different jurisdictions, and the local board can call you in for an uncomfortable pow-wow.

So let's review - how much is the hassle worth ? IMO it's not worth .02


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## patmurphey (May 28, 2013)

A city of 250,000 with no standby generators installed? We haven't heard back from the OP yet about inquiries to dealers or the city about zoning variances. Nor, have we heard of any effort to modify the noise regulations to permit use of a "typical, fairly quiet, permanent" standby generator during a legitimate power outage.


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## patmurphey (May 28, 2013)

250,000 is closest to St. Paul's population, and the OP says he's from the twin cities. If that's the case it appears that the noise regulation after 10 PM is 55db at 100 feet. in the chart posted above, 67db at the typically measured 7 meters would just barely make it under 55db at 100 feet. Air cooled 20kw Generacs and Cummins/Onans by published specs are rated under 67db at 7 meters.


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