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Quick help with Onan 12.5


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  #101  
Old 04-15-2017, 11:03:11 AM
Ray Lynch Ray Lynch is offline
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Default Re: Quick help with Onan 12.5

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Originally Posted by Max Thompson View Post
That info is in #T-015 gaseous fuels manual. I think it is on the twainslan site.
It's there.
Ray

http://www.twinslan.net/~n0nas/manuals/onan/
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  #102  
Old 04-15-2017, 11:47:47 AM
nothingbutdarts nothingbutdarts is offline
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Default Re: Quick help with Onan 12.5

Being I just had the T-015 manual out yesterday giving the propane company the consumption for a SK, I will post full load consumption for your 12.5 JC: 92 Cubic feet per hour propane and 228 cubic feet for natural gas.

Last edited by nothingbutdarts; 04-15-2017 at 01:18:53 PM. Reason: spelling
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  #103  
Old 04-15-2017, 12:00:14 PM
len k len k is offline
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Default Re: Quick help with Onan 12.5

That's ~ 230k Btu/hr , which is about 2x as much as your house furnace uses.
Look at the gaseous fuel manual, you may have to increase your gas pipe diameter to fuel the gen , and have gas co change the flow restrictor in the meter outlet.

Or have gas co up it's pressure to 2 psi.

Last edited by len k; 04-15-2017 at 12:54:49 PM.
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  #104  
Old 04-15-2017, 02:40:30 PM
Handyhiker1 Handyhiker1 is offline
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Default Re: Quick help with Onan 12.5

I have a 1.5" main line with the boiler and hot water tank sharing a 1/2" line. The only other gas I use is for the burners on the stove, the oven is electric. I only need to run about 25' to the outside wall where the generator hook up will be. From the chart that I looked at in the T-015 manual (thanks for the info), it looks like 1" pipe will work in the house.
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  #105  
Old 04-15-2017, 03:59:12 PM
len k len k is offline
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Default Re: Quick help with Onan 12.5

1" pipe sounds small, but I haven't looked at manual.
Others know this stuff off the top of their head without looking in manual.
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  #106  
Old 04-15-2017, 04:05:24 PM
Handyhiker1 Handyhiker1 is offline
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Default Re: Quick help with Onan 12.5

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1" pipe sounds small, but I haven't looked at manual.
Others know this stuff off the top of their head without looking in manual.
I will recheck when I have a little more time to actually sit down and read it. Just took a quick glance today.
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  #107  
Old 04-15-2017, 08:16:15 PM
Max Thompson Max Thompson is offline
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Default Re: Quick help with Onan 12.5

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Originally Posted by len k View Post
1" pipe sounds small, but I haven't looked at manual.
30' of 1" BLK iron will deliver 377 CFH (377,000 BTU). Add 10' for each 90 degree turn, (going around a tee = a 90). Not knowing how long your run of 1 1/2" is, but "assuming 140 CFH for the boiler and 40 CFH for the water heater, I will bet you will be in good shape.

Double check the size of your existing trunk line. In my area, 1 1/2" (ID) is uncommon in a residential system, 1 1/4" was "standard" back in the old days and now we rarely run anything larger than 1". Commercial is a whole different game.
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  #108  
Old 04-16-2017, 08:24:50 AM
Handyhiker1 Handyhiker1 is offline
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Default Re: Quick help with Onan 12.5

My meter is right outside the front wall of the house and comes in the basement. It goes through 2 elbows to my main trunk line. it is all the same size at 1-1/2" pipe. The guy that built this house, we are the third owner, built it to commercial specs. I know that sounds weird but all of our 1st story floors are poured concrete with steel girders in the basement ceiling for support. I have no support posts in the basement. The basement walls are 18" thick and fire rated block, the upstairs walls are 2x6 stud plus brick and insulation board.
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  #109  
Old 04-16-2017, 10:25:14 AM
Max Thompson Max Thompson is offline
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Default Re: Quick help with Onan 12.5

Sounds like a "preppers" dream home.
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  #110  
Old 04-16-2017, 11:44:22 AM
Handyhiker1 Handyhiker1 is offline
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Default Re: Quick help with Onan 12.5

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Sounds like a "preppers" dream home.
When we bought it, the neighbors called it the "bomb shelter house". Everything is poured concrete.
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  #111  
Old 04-16-2017, 12:14:27 PM
len k len k is offline
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Default Re: Quick help with Onan 12.5

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Everything is poured concrete.
No termites.
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  #112  
Old 10-17-2017, 08:00:40 PM
Handyhiker1 Handyhiker1 is offline
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Default Re: Quick help with Onan 12.5

I decided to just add to this thread since it is this 12.5 JC that I am still working with. Just a recap, it now runs as it should and all controls work. It puts out good voltage and I have been able to put smaller loads on it up to about 5000 watts. I kicked around the idea of a perminate mounting and use NG as a fuel but we just don't have many problems with our power. So I am building a cart to hold it. That is were the new story begins.

I had to work for a bit today even though I was on a vacation day, 24 hour call sucks. When I got home I decided to tinker in the barn for a bit. Here is what I came up with for the JC.

The fuel tank is an 18.75 gallon and has 2 ports. One will go the the generator and the other will be a drain port that I can fill my zero turn and Polaris Ranger with so I can keep fresh gas in the generator tank. Total weight of the tank and fuel should be around 150# when full. I am planning on adding a heat shield under it to try to keep it from getting too hot. I know that I will need to use a fuel shut off valve with the fuel above the engine, there is one on the end of the fuel bowel but I am thinking of adding an electric one as well. I have the extra hole in the face of the control panel that I could mount a momentary on switch in and then when the generator starts it could supply the 12 volts to keep it open. If I use a diode there would not be any back feed to the circuit used to power the valve. That way if the engine did shut off, the valve would close as a safety.

The batteries are heavy and they are deep cycle 6 volt sealed. I have them wired in series with a quick disconnect just in front of the battery tray. There is plenty of room to hook up my battery tender. I took the pics then played around with it. Total weight of the batteries has to be around 80# - 100#.

The electrical output will go the the breaker box that is mounted just under the handle. It was a used freeby but came without breakers. I bought 4- 15 amp and 4- 20 amp breakers. I still need to pick up a 240 volt breaker so I can install a 240 plug, I am thinking of using two different colors for the 120 volt outlets, a different color for each winding so it would be easy to balance the load. I would guess total weight of electrical components around 20#. I have most of the supplies so this should go fairly quickly once I get to this point.

The cart was a freeby as well, actually got two of them as they were headed for the trash. Not sure what it is rated to hold but it is a heavy duty 6 wheel cart. All the casters have grease fittings for both the axle and the spinner bearings. With the way it is in the current pictures, it is still fairly easy to move around. I would guess the cart weight to be in the 100# range as it took 2 of us to load them in my van.

It is a work in progress as today was just figuring out how and where to mount things. Still need to brace the fuel tank, run output wiring and outlets. Then plan to add a drain hose for the oil to make changes simpler.
So as of now it looks like the total weight including a full fuel tank is going to be in the 1125# - 1150# range. Run time should be 8 hours full load to 18 hours no load.
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  #113  
Old 10-17-2017, 11:05:40 PM
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Default Re: Quick help with Onan 12.5

One issue you might consider with having the fuel tank on top is engine flooding with fuel when shut down. If you forget to shut off the fuel at the tank and you have a needle and seat in the carburetor that sticks or seeps, you will have gasoline pushing past the fuel pump and into the carburetor, flooding over either into the engine or onto the floor creating a fire hazard.
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  #114  
Old 10-18-2017, 12:02:58 AM
len k len k is offline
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Default Re: Quick help with Onan 12.5

Fuel solenoid would fix that
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