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Kohler 20resc Natural gas


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  #1  
Old 11-25-2018, 05:37:34 PM
Krislu Krislu is offline
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Till now,I have only owned a Honda EU2000I portable ( sold it,after 1 month needed a ring and valve job, smoked too much, dealers would not warranty) and a Yamaha 2400 ( excellent,still have) This is my first experience with a home generator. It's a 3 month old Kohler 20resc Natural gas generator that coded "over crank " for the first time. I noticed on a Saturday night when the power was out. It happened the Wednesday before on exercise day. I didn't know it wasn't working til Saturday. Paid the dealer an outrageous rate to come take a lookse. I asked him about Kohler's Oncue and he told me to avoid, said it's down most of the time and I would need him to reset it. Anyway, he came up with a little low gas pressure, said between 5 -5 1/2 wc he said he wasn't concerned because on start up it went down a little but came back up once running. He said I should add the pressure regulator heater, said all of the unit should come with it but don't. I had the gas company come out to raise the pressure. The guy said he made it 6.8 wc. I checked the spark plug gap and discovered one was .020 and the other was not even that. So I gapped at .030. My question: Will the heater make that much of a difference? I plan on installing it myself.

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Kris
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Old 11-25-2018, 07:14:28 PM
Zephyr7 Zephyr7 is offline
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Default Re: Kohler 20resc Natural gas

I don’t see a point in heating the gas regulator. You don’t have to boil off gas on a natural gas set, it’s already gaseous fuel (propane sometimes has issues with enough gas boiling off from liquid when it’s really cold outside). Kohler sells a carb heater option, and that is usually supplied by dealers if you’re in a cold enough area to need it. He carb heater is an option you should have.

I doubt the gap was your problem unless the other plug was really messed up.

Bill
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Old 11-25-2018, 10:13:31 PM
Mark Dieckmann Mark Dieckmann is offline
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Default Re: Kohler 20resc Natural gas

You should probably check out the spark plug gap specs. If my memory serves me, it is supposed to be .020. I would agree that a carb heater is the first thing you need. The OC fault means that it failed to start. I think gas inlet pressure is supposed to be between 7-11 inches.
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Old 11-26-2018, 12:19:53 AM
Zephyr7 Zephyr7 is offline
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Default Re: Kohler 20resc Natural gas

Some of the air cooled resi gensets are specced for 3.5-11” WC inlet pressure. Best not to be in the low end of that range though. I always recommend 11” pressure.

The liquid cooled sets are specced for 7-11” WC inlet pressure.

Bill
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Old 11-26-2018, 12:28:10 AM
Newoldstock Newoldstock is offline
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Default Re: Kohler 20resc Natural gas

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Originally Posted by Zephyr7 View Post
Some of the air cooled resi gensets are specced for 3.5-11” WC inlet pressure. Best not to be in the low end of that range though. I always recommend 11” pressure.

The liquid cooled sets are specced for 7-11” WC inlet pressure.

Bill
Got one that's air cooled and spec 11" only....
Canadian version of K181EP on 3RM22 head
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Old 11-26-2018, 10:27:18 AM
Zephyr7 Zephyr7 is offline
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Default Re: Kohler 20resc Natural gas

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Got one that's air cooled and spec 11" only....
Canadian version of K181EP on 3RM22 head
Is that for propane? It will only be the natural gas sets that can go down to the lower pressures. I think the only reason they allow for pressures down to 3.5” on some units is so that the typical residential service pressure of 7”, after some drop in the piping, will still be ok when it gets to the genset. They don’t want to scare off customers by requiring upgraded gas pressures and bigger piping. There are also some areas served by low pressure gas mains where elevated pressure might not even be an option.

Bill
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Old 11-26-2018, 10:50:01 AM
Newoldstock Newoldstock is offline
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Default Re: Kohler 20resc Natural gas

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Originally Posted by Zephyr7 View Post
Is that for propane? It will only be the natural gas sets that can go down to the lower pressures. I think the only reason they allow for pressures down to 3.5” on some units is so that the typical residential service pressure of 7”, after some drop in the piping, will still be ok when it gets to the genset. They don’t want to scare off customers by requiring upgraded gas pressures and bigger piping. There are also some areas served by low pressure gas mains where elevated pressure might not even be an option.

Bill
The tag just says natural gas 11' W.C. inches and 63000 btu/hours.
I don't know very much about the technical details of NG or propane kits.
That's 18,500 watts thermal for 3000 watts power output or about 16% efficient. ( hoping to improve that with a purpose built high compression replacement engine )

By my math the engine is about 20% over powered for the application displacing over 300cc for a load a modern OHV engine can do on gasoline with 1/3 less cubes.
I assume this has something to do with the gas conversion
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Old 11-26-2018, 11:48:53 AM
Zephyr7 Zephyr7 is offline
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Default Re: Kohler 20resc Natural gas

I get just shy of 6kw out from the engine just converting 8HP to kw at 746w/HP, so you should be about 32% efficient at full engine load, assuming that’s how they rated it for fuel consumption. 32% efficiency is pretty good!

Natural gas and propane both have a fair bit less energy per unit volume than gasoline, so you need more displacement to get the same HP output when running on one of those gaseous fuels.

Bill
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Old 11-26-2018, 11:49:55 AM
Birken Vogt Birken Vogt is offline
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Default Re: Kohler 20resc Natural gas

Phantom problems like this, you have just got to "sneak up" on them. Set everything back to normal and observe it next week at exercise time. Hopefully you can catch it in the act. Only call the dealer out when you have observed whatever happened in person and can explain what you saw a little better. Assuming you have a good technician who listens to customer data and can interpret.
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Old 11-26-2018, 12:07:09 PM
Newoldstock Newoldstock is offline
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Default Re: Kohler 20resc Natural gas

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Originally Posted by Zephyr7 View Post
I get just shy of 6kw out from the engine just converting 8HP to kw at 746w/HP, so you should be about 32% efficient at full engine load, assuming that’s how they rated it for fuel consumption. 32% efficiency is pretty good!

Natural gas and propane both have a fair bit less energy per unit volume than gasoline, so you need more displacement to get the same HP output when running on one of those gaseous fuels.

Bill
There might be an error in your math Bill.
You generally need a touch more than 2 hp per kW in an implication like this.
Assuming an efficiency of 60% on the alternator is a step I think you skipped.
Such a small machine will not be efficient, the head I have here is a brush type with saturated field ( no regulator ) and lose tolerances.

Engine alone I am not sure its possible to get 30% efficiency on a gas fuel flat head.
My numbers might be even worse than 15%...
I would really have to measure and not guess so much....
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