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Onan 15.0JC Information and opinion


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  #1  
Old 12-12-2013, 03:58:25 PM
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Default Onan 15.0JC Information and opinion

Hello all. I think you dang guys gave me the bug! been keeping up on this site every day I am considering a new to me purchase its a

MODEL 15.0JC-3CR/4017S
SERIAL 0871310248
Been run on natural gas all its life.
what do you guys think? does anyone have information on this generator I have not seen it in person yet, hopefully this weekend. is there anything special to look for when I do get a chance to look at it?
if I do buy it you WILL be the first to know.

email: wraejr@charter.net
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  #2  
Old 12-12-2013, 04:31:52 PM
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Dave Edmonds Dave Edmonds is offline
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Smile Re: Onan 15.0JC Information and opinion

Four cylinder, air-cooled, 120, 240, or 120-240 single-phase. Relatively new for a JC. Natural gas fuel is a plus, if you plan to run it on either natural gas or propane.
Excellent whole-house standby generator, easy maintenance (no radiator, water pump, or anti-freeze), most parts are still available.
I don't have one of these, but I would certainly buy one if it came along at the right price (even if I didn't really need it!).
Manuals are available on this forum.
Dave Edmonds
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Old 12-12-2013, 04:35:51 PM
Isaac-1 Isaac-1 is offline
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Default Re: Onan 15.0JC Information and opinion

Dave I think you misread that serial number, spec code S should be an older Magniciter series unit, still everything else holds true, just it is the older generation of the J series, which makes some parts a bit harder to find, but otherwise a great unit.

Ike

p.s. these came with a wide range of options ranging from bare skid mounted units with only a DC charging meter, to full instrumentation and weather housings
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Old 12-12-2013, 04:41:44 PM
len k len k is online now
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Default Re: Onan 15.0JC Information and opinion

JC is a nice machine, I almost bought one cheap several years ago when I started looking for a gen. It was too powerfull for me, and heavy. Look at your power needs, in general larger gensets have larger baseline (no-load) fuel consumption. A JC makes 15kw (4 cylinder), a JB makes ~7.5kw (2 cylinder).

Last edited by len k; 12-12-2013 at 04:59:43 PM.
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Old 12-12-2013, 04:51:50 PM
Isaac-1 Isaac-1 is offline
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Default Re: Onan 15.0JC Information and opinion

Oh one thing, do you plan to run it on natural gas or propane? I ask because one of the options on the 15JC was natural gas only high compression pistons. As to things to look at, I would want to see it run and generate electricity, if it did and the price was right I would grab it.

Ike
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Old 12-12-2013, 04:52:30 PM
John Ward John Ward is offline
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Default Re: Onan 15.0JC Information and opinion

Mine is one year older (Aug 1970) with less options but is still a Spec "S". 700+ lbs of American cast iron muscle designed to last many, many, years. Definitely a "Magniciter" genend.
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Old 12-12-2013, 05:39:34 PM
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Default Re: Onan 15.0JC Information and opinion

I plan on running it on natural gas. I have a 1" line from my meter. is there a way to tell if its a gaseous fuel only model by the numbers I gave?
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Old 12-12-2013, 05:57:33 PM
John Ward John Ward is offline
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Default Re: Onan 15.0JC Information and opinion

Quote:
Originally Posted by brae View Post
I plan on running it on natural gas. I have a 1" line from my meter. is there a way to tell if its a gaseous fuel only model by the numbers I gave?
A 15.0JC is going to consume approx. 255K BTU/Hr (255 CFH) at full load. How large is your gas meter, how long is the run, and how many appliances are off that 1" line?

**** Removed chart because it did not comply with the IFGC table 402.4(2) **** Sorry!

Table 12 in the Onan T-015 manual should be consulted if you do not have access to the IFGC (International Fuel Gas Code) book.

http://www2.iccsafe.org/states/seatt...Chaper%204.pdf

Last edited by John Ward; 12-12-2013 at 10:37:09 PM.
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Old 12-12-2013, 06:11:04 PM
Leon N. Leon N. is offline
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Default Re: Onan 15.0JC Information and opinion

From my 40 + years of experience with the smaller version, i.e., the JB, running on natural gas is the way to go for many reasons. Also, since the plant originally ran on natural gas, the wear in the cylinders hopefully would be low, depending of course on what kind of lube oil maintenance was performed by the previous owner. NG is less severe on the machine than either gasoline OR propane.

This machine was built to the factory revision "S" where as my JB was of "P". So you have a Magneciter generator end. If the Magneciter looks OK by visual inspection then from that standpoint alone YOU HAVE A GEM! They don't build them like that anymore.

BTW, you mentioned feeding a 1 inch gas line to the JC. That is ok for a short piping run. I and others have the Onan tech bulletins, such as T-015 which specify diameter of the diameter of the NG gas line for various plants and lengths of pipe.

Make sure before you buy, do a visual inspection, and include removing the two machine screws with a screw driver to peak at the Magneciter coils to make sure they are not burnt or over heated. Also check the lube oil for water, etc..

I will email you a copy of my T-015 for openers. Good Luck.
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Old 12-12-2013, 06:32:34 PM
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Default Re: Onan 15.0JC Information and opinion

Quote:
Originally Posted by John Ward View Post
A 15.0JC is going to consume approx. 255K BTU/Hr (255 CFH) at full load. How large is your gas meter, how long is the run, and how many appliances are off that 1" line?

http://www.engineeringtoolbox.com/na...ing-d_826.html
John I don't believe I will ever have enough load to fully load this unit I somewhat believe bigger is better and with natural gas carbon buildup shouldn't be an issue. my gas line runs from my furnace the hardest this gen will run is in the summer for a/c so I doubt I will run out of gas.
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Old 12-12-2013, 07:12:14 PM
Leon N. Leon N. is offline
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Default Re: Onan 15.0JC Information and opinion

John that chart you referenced in #8 does not agree with the Onan information on pipe sizes for various lengths mainly because the Onan information pertains to a line pressure of 11 inches and not as your reference says "pressure below 1 and 1/2 psig.
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Old 12-12-2013, 07:27:12 PM
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Default Re: Onan 15.0JC Information and opinion

Thank you for the T-015 manual.
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Old 12-12-2013, 08:16:52 PM
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Default Re: Onan 15.0JC Information and opinion

First sign of life was on May 24th 1971.
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Old 12-12-2013, 08:26:09 PM
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Default Re: Onan 15.0JC Information and opinion

So cool thanks!
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Old 12-12-2013, 10:28:41 PM
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Default Re: Onan 15.0JC Information and opinion

Quote:
Originally Posted by Leon N. View Post
John that chart you referenced in #8 does not agree with the Onan information on pipe sizes for various lengths mainly because the Onan information pertains to a line pressure of 11 inches and not as your reference says "pressure below 1 and 1/2 psig.
Thank you Leon, I edited my post to reflect the issue.

Quote:
Originally Posted by brae View Post
John I don't believe I will ever have enough load to fully load this unit I somewhat believe bigger is better and with natural gas carbon buildup shouldn't be an issue. my gas line runs from my furnace the hardest this gen will run is in the summer for a/c so I doubt I will run out of gas.
So you do not anticipate a power outage dead of winter when you need your furnace, possible water heater, and cook stove?
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Old 12-12-2013, 10:47:39 PM
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Default Re: Onan 15.0JC Information and opinion

Being able to power my oil furnace for heat when power is out in cold 5 deg winter is the ONLY reason I got a gen.
Few years ago neighborhood behind me was out for a week after massive ice storm hit the Northeast, could have been me.
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Old 12-12-2013, 11:37:44 PM
Leon N. Leon N. is offline
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Default Re: Onan 15.0JC Information and opinion

During the blizzard of '78 I ran my JB for two weeks. What is interesting is that the average load over any 24 hour period was very low. Probably around 1 KW with peaks around 5-6 Kw. That is why the diversity factor is so important.

For example, around here the local utility installs 25 KVA pole mounted transformers for every 7 houses. Where there is a house using electric heat, they utilize a dedicated 25KVA transformer for that home. With most folks now having installed central air, I am amazed we have not seen any transformer over load failures.

Back in 1970 when I purchased the JB, I almost bought a JC but because of fuel consumption, I settled on the JB and a 5CCK. I really liked the 5 CCK but it turned out to be bit to small. Fortunately, the JB had a very conservative rating which turned out to be very helpful in starting our 3 ton AC.
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Old 12-12-2013, 11:50:44 PM
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Default Re: Onan 15.0JC Information and opinion

When I looked at a JC the fuel consumption numbers drove me away too. I probably only use < 1kw on average so I likely could get away with a 4-5kw gen but I worried there would be problems if my oil furnace and fridge tried to start at same time. They each took ~25amps during starting. I got lucky and stumbled upon a real cheap 7KW RV Onan NHM. I diagnosed that it just needed carb cleaning and AC regulator, was asking $400, I gave him $200 cash and hauled it away. With 7kw now I can use stove and oven if I want. But mine does have design defect (common to all the Emeralds), the AC reg likes to die if it sits for several months and you don't clean slip rings before use.

Last spring ~ 8pm a hot humid front rolled in, everyone put on AC. Shortly after one of city's substation transformers over heated, power was out for most of the night till it cooled down. Also utility is adding pole transformers along some streets.

Last edited by len k; 12-13-2013 at 01:05:48 AM. Reason: add Emerald info
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Old 12-13-2013, 08:02:01 AM
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Default Re: Onan 15.0JC Information and opinion

Quote:
Originally Posted by len k View Post
When I looked at a JC the fuel consumption numbers drove me away too. I probably only use < 1kw on average so I likely could get away with a 4-5kw...
Same here. It's the baseline fuel usage that is the deal breaker. Roughly 1 GPH gasoline with no load. Without natural gas available it is just not practical to run the JC lightly loaded for any length of time.
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Old 12-13-2013, 12:00:21 PM
Leon N. Leon N. is offline
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Default Re: Onan 15.0JC Information and opinion

len K re your comment: "---But mine does have design defect (common to all the Emeralds), the AC reg likes to die if it sits for several months and you don't clean slip rings before use.---".

How are you storing this unit? Is it outdoors where it sweats? I would think if you stored it in a dry shed, you should not have the problem you mention. What do you think?
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