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Onan: 20ES B spec 55890E sn C920452352

20ES B
spec 55890E
sn C920452352
This unit has a little over 700 hours on it. Wired for 120/240.
Running on propane ..
Proposed use: 3phase 120/208 on natural gas.
There are four heavy leads, and 11 or so 18-gauge or perhaps 16-gauge white wires.
Q1: is there anything that I need to do to use NG vs Propane?
Q2: are there any gotchas or warnings about changing to 3ph, and is there perhaps a video of the changeover?
Q3: is 3000$ too much to pay with it's transfer switch(3pole solid neutral)?
Thanks!
Tom
 

Max Thompson

Sponsor
Last Subscription Date
09/03/2019
#1, maybe some carb adjustment to run on nat. gas, check the regulator position and whether the spring is still in it.
#2 voltage change is pretty straight forward if all the numbers are legible on the gen-leads. Not sure you have found the leads yet, there should be 12 of them, none under 8 ga. (assuming this is a 12 lead, reconnect-able set.)
#3 Price is dependent on many things. If it functions as it is supposed to and you are happy, the price is fair.

#1 & #2 are covered in the manuals available here http://www.skilledcrafting.com/onanfiles/ Service manual #900-0335. Some pictures of the set, gas piping & regulators, wiring in junction box under control panel, would help us help you.

If I get some time later today, I will look up the build sheet and we can tell you more. Maybe one of the others here can post it sooner.
 

Birken Vogt

Registered
20ES B
spec 55890E
sn C920452352
This unit has a little over 700 hours on it. Wired for 120/240.
Running on propane ..
Proposed use: 3phase 120/208 on natural gas.
There are four heavy leads, and 11 or so 18-gauge or perhaps 16-gauge white wires.
Q1: is there anything that I need to do to use NG vs Propane?
Q2: are there any gotchas or warnings about changing to 3ph, and is there perhaps a video of the changeover?
Q3: is 3000$ too much to pay with it's transfer switch(3pole solid neutral)?
Thanks!
Tom
Four heavy leads makes it sound like it might be single phase only. Better look closely before you buy. There should be 12 power leads numbered 1-12 terminated on plastic insulator blocks with studs to do what you want. There will usually be a diagram of both types under the cover of the generator area. If it is single phase there will be 4 numbered 1-4.
 
#1, maybe some carb adjustment to run on nat. gas, check the regulator position and whether the spring is still in it.
#2 voltage change is pretty straight forward if all the numbers are legible on the gen-leads. Not sure you have found the leads yet, there should be 12 of them, none under 8 ga. (assuming this is a 12 lead, reconnect-able set.)
#3 Price is dependent on many things. If it functions as it is supposed to and you are happy, the price is fair.

#1 & #2 are covered in the manuals available here http://www.skilledcrafting.com/onanfiles/ Service manual #900-0335. Some pictures of the set, gas piping & regulators, wiring in junction box under control panel, would help us help you.

If I get some time later today, I will look up the build sheet and we can tell you more. Maybe one of the others here can post it sooner.
Have to drive to get good pics, and didn't want to put a bunch up to spare the folk with restricted bandwidth connections... I'll use your suggestions to get 'the right' pics...
Thanks, Tom
 
Sadly the seller re-advertised it on Portland CL with now explicit false claim that it does 3phase, after I called and explained that y'all provided the build sheet and that it's single phase 120/240 only... Go figure. I might post the build sheet to CL if he doesn't take it down, but ... no time to do the work I need to get done... not sure if a bot will eat the URL, but here it is in it's bold lying glory:
https://portland.craigslist.org/wsc/tls/d/hillsboro-onan-20kw-generator-1ph-and/7136101656.html
some people and their kids! The actual seller is a collector of various things including immaculate old cars, I'm kinda surprised at this.
 

Vanman

Subscriber
Last Subscription Date
06/10/2020
Well.... It isn't entirely impossible that the generator has been replaced at some point, no longer reflecting the original build sheet...?
 

EricWood

Subscriber
Last Subscription Date
10/15/2019
I’m going to guess seller is ignorant to the function of the switch on the control panel. It’s amazing how many people vaguely familiar with generator terminology think that switch is for converting between three phase and single phase, when it’s only purpose is to give proper readings on the meters, provided sensing and CT leads were correctly done during any possible conversion. Standard silkscreen print on the door, so in 4-wire application that switch is only used in the bottom two positions.
 
Well.... It isn't entirely impossible that the generator has been replaced at some point, no longer reflecting the original build sheet...?
No indication of that - just the cobbled together light duty wiring to "show it makes power" - attached to 4 heavy wires... I'll keep looking for -15 or -18 and settle for -4 if needed - have a line on one of those, that's been living under a tarp for a few years (eeek!)
 
I’m going to guess seller is ignorant to the function of the switch on the control panel. It’s amazing how many people vaguely familiar with generator terminology think that switch is for converting between three phase and single phase, when it’s only purpose is to give proper readings on the meters, provided sensing and CT leads were correctly done during any possible conversion. Standard silkscreen print on the door, so in 4-wire application that switch is only used in the bottom two positions.
Yup, I even wondered if the switch was controlling an array of relays that did the reconnect :) Ok - all better now ...
 

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