gee
Hello I have a 4390-3 and i was wanted to know how much NG do it need to run it.
I see on a older post that 11-14" of water column @ .5psi is what a 4390-0 and
a 3490-1. What does a 4390-3 need ? I have looked for a manul for this but not finding one.
Here is the ser number for it 3986493.This unit ran on propane before i got it. I replaced the one jet on the reg
and it does run with 1/4 load on it. Thanks for the help.Gene
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JayH
There are two considerations with fuel. One is the pressure and the other is the flow capacity. For natural gas 11-14"seems high but I'll let the experts familiar with that specific model and serial number weigh in. As far as flow rate, the length and size of the pipe between the regulator and generator need to be adequate to supply sufficient fuel under load. If you can supply the length and size of pipe as well as the number of elbows, this can be calculated. In addition, the regulator itself must be sized such that it can supply sufficient fuel volume.
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gee
From the meter i have 1 in pipe run about 14 ft with 3 elbows. Then it goes to the 3/4 flex hose (6 in)1 more 90 3/4 at the reg. I was reading a old post about the meter may not have flow it needs. I do run my house 60,000 btu heater and water heater (30 gal) on nat gas too. It seems like a lot to run off of the meter.I have a call in to CIPS and hope some one will call soon.I have had the Generac running and turn the heat on and it seems to run ok with a 30amp load on it. The temp was about 50 out side.
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Peddler
You need 7" of water column on a 4390-3, the earlier 4390-0 called for 11" of nat gas but then was changed on the later versions.
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BillM
You've got the GT-990 engine in there which under full load only burns 220 cubic feet per hour.  Refer to page 7 of the installation manual, it calls for 5" to 7" water column which is .18 to .25 PSI.  It is recommended to not exceed .25psi for that generator.  I have sent you a PM on this forum with the directions to get to your installation and owners manual online directly from Generac's website, not a 3rd party.  The numbers you quoted in your original post are closer to LP gas requirements, but still too high for that generator.  Good Luck.  
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BillM
Sorry, I see Peddler already replied 1 minute before me.  I see from Peddler's note where you came up with the 11-14" reference.  And it looks like you have great piping.  I'm running a bigger generator with pipe a lot longer and with so many elbows a Chinese contortionist would be jealous.  
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BillM
If you look at the model # on your meter, you could look up what it's specifications are.  I'd be surprised if any base meter doesn't have the delivery capability to run all that you have specified.
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gee
Thanks for all the info. You guys are great
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