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Onan Generators

Onan 20ES L25208B


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  #1  
Old 10-22-2016, 11:08:34 PM
Komrade Komrade is offline
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Default Onan 20ES L25208B

serial: 0900315980

I bought this generator from a guy that said he removed it from a local school as part of an upgrade. It had low hours (low hundreds), and appeared to be in a very good shape. I believe it was there to keep the lights on in case of a blackout, and they were upgrading with generators that could provide enough juice for AC as well.

Can one tell if this is an LP or Nat Gas unit (i thought the only difference should be the regulator)

It has a cut 1.5" pipe for the gas. It have a good battery for it.

I'd like to attach it to a 40lb tank and get it started before I invest into bigger LP tanks.

What regulator do I need in between? What should my next steps be in order to get it tested?






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Old 10-23-2016, 12:02:18 AM
akirkland akirkland is offline
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Default Re: Onan 20ES L25208B

Provide 11" water column to this unit. The demand regulator is upside down, this is how an LP unit is normally set up, check the demand regulator and make sure the spring is removed. It is under the white plastic adjusting screw/cap, which in turn is in the demand regulator tower under the aluminum cap.
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Old 10-23-2016, 12:02:30 AM
Ray Lynch Ray Lynch is offline
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Default Re: Onan 20ES L25208B

Komrade
Looks like a "D" instead of a "0" at the beginning of the Onan serial number. Generator made April 1990.
Ray
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Old 10-23-2016, 12:24:23 AM
akirkland akirkland is offline
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Default Re: Onan 20ES L25208B

The demand regulator is to the left of the fuel flex line. Check fluid levels, visually check engine for any obvious problems. Whoever cut the fuel line probably was not careful with the ac output wires. Make sure the ac output wires are safe, wire nuts or tape is good. Units this age frequently need cooling system service, check water pump for looseness, check belts, check battery cables for tightness,corrosion, check immediately. For oil pressure on startup, watch for leaks, check ac voltage, frequency, be ready to shut it down immediately if you see a problem.
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Old 10-23-2016, 07:29:38 AM
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Default Re: Onan 20ES L25208B

do I need to worry about this unconnected wire?

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Old 10-23-2016, 09:42:04 AM
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Billy J Shafer Billy J Shafer is offline
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Default Re: Onan 20ES L25208B

Most ES units could also run on gasoline. I just worked on one. Post a photo of the block same side as carb. Don't worry about that wire. It is only for a test. You don't need it I agree on checking the wires. When they removed the one I worked on. They just used a cutter and cut the wires while they were still powered up on the DC side. I would also remove the fan guard and trim it up. To give the fan a little more room. If not set down flat. The blade tips can hit the guard.
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Last edited by Billy J Shafer; 10-23-2016 at 09:53:04 AM.
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Old 10-24-2016, 10:34:39 AM
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Default Re: Onan 20ES L25208B

What's the best way to go from 1.5" pipe to a propane tank hose

Anyone want to help me save a lot of time by talking to mostly (but not always) clueless Lowes and Home Depot associates?
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Old 10-24-2016, 11:43:44 AM
Birken Vogt Birken Vogt is offline
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Default Re: Onan 20ES L25208B

You wanting to run it off a bottle temporarily? Not sure about the question.

This is what you need: http://www.ebay.com/itm/New-Fisher-R...YAAOSwZJBYBVvT

Plus associated fittings to get the pipe from the regulator to the generator.

Lowes, etc. usually does not have a regulator big enough to run this thing.
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Old 10-24-2016, 01:29:25 PM
Komrade Komrade is offline
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Default Re: Onan 20ES L25208B

Thank you very much for posting a link to the regulator I need.

What pipe size output would this have?

That way I could order this, and purchase the rest of fittings to get it to 1.5" pipe inside the generator.

P.S.
looks like

1/2" FNPT

http://www.squibbtaylor.com/product-...d=6512&cid=302
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Old 10-29-2016, 10:32:06 PM
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Default Re: Onan 20ES L25208B

I got the recommended regulator. Will work on detaching the pipe and figuring out how to connect it next week

Here are a few more pics

Other side, as requested


3 wires


what's this one for?


the controller wires were cut, and will need to be insulated (I have the remote controller)

hours (<700)
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