Residential Standby Generators - Onan, Kohler, other

Post by Jeff Neese
Decided to install a natural-gas stanby generator. I have propane now, but
will am having natural gas run to my house specifically for the generator.
Propane will act as backup fuel (with a simple conversion, of course) so in
the unlikely event that both electricity and gas go out, I still have power.
Don't need much, just enough to run the well pump, furnace, hot water
heater, and a couple of other key devices like perhaps the refrigerator.
Making sure that an extended outage, especially in winter, doesn't cause me
to have to leave because I have no heat or water.
Pretty much got it narrowed down to the Onan RS12000 or the Kohler 11RMY,
very similar generators. I've compared specs, researched the engines, and
pretty much now the minor differences. I'm looking for any real-world
experience or advice, about these generators specifically, Onan vs. Kohler
in general, or any other advice that might be helpful.
Thanks in advance.

Go with the one that turns at the lower RPM. When I was looking for a
backup for my off-grid system, the ONAN was a 3600 rpm unit and the Kohler
was an 1800 rpm unit. Also, the Kohler had a much better warranty. That
may not be as important in a backup situation.

Also, I do not believe you can rig up a simple "switch" to go between NG
and propane. I'm pretty sure you have to at least change nozzles, and
there may be more involved.

-- ron (off the grid in Downeast Maine)

Jeff Neese

2003-09-02 01:02:46 UTC

Both the Onan P224 engine and the Kohler CH25 are two-cylinder, air-cooled
engines that turn at 3600. And yes, it's not just turning a switch, but the
conversion from NG to propane is something that I could do myself
(field-switchable). Thanks.

Post by Ron Rosenfeld

Go with the one that turns at the lower RPM. When I was looking for a
backup for my off-grid system, the ONAN was a 3600 rpm unit and the Kohler
was an 1800 rpm unit. Also, the Kohler had a much better warranty. That
may not be as important in a backup situation.
Also, I do not believe you can rig up a simple "switch" to go between NG
and propane. I'm pretty sure you have to at least change nozzles, and
there may be more involved.
-- ron (off the grid in Downeast Maine)

Ron Rosenfeld

2003-09-02 01:54:27 UTC

Post by Jeff Neese
Both the Onan P224 engine and the Kohler CH25 are two-cylinder, air-cooled
engines that turn at 3600. And yes, it's not just turning a switch, but the
conversion from NG to propane is something that I could do myself
(field-switchable). Thanks.

Well, you made me go and look at my manual. What I have is the Kohler 12RZ
which has a Ford engine. Obviously a different beast than the one you are
looking at.

But I do note something interesting which you may want to check on yours.
On mine, the rating is significantly higher on LP compared with natural
gas. The natural gas rating on the 12 RZ is 9kW, while the LP rating is 12
kW.

Best,

-- ron (off the grid in Downeast Maine)

Steve Spence

2003-09-03 00:55:20 UTC

lp has a higher btu than natural gas.
--
Steve Spence
www.green-trust.org

Post by Ron Rosenfeld

Well, you made me go and look at my manual. What I have is the Kohler 12RZ
which has a Ford engine. Obviously a different beast than the one you are
looking at.
But I do note something interesting which you may want to check on yours.
On mine, the rating is significantly higher on LP compared with natural
gas. The natural gas rating on the 12 RZ is 9kW, while the LP rating is 12
kW.
Best,
-- ron (off the grid in Downeast Maine)

Jeff Neese

2003-09-05 01:21:10 UTC

I was actually looking at the 10RZ, similar liquid-cooled Ford engine but
with less output. However, because this as standby and SHOULD get few hours
(not like I'm going off-grid or anything), any of the small industrial
twin-cylinder air cooled engines should last me a lifetime with proper care
and maintenance. And if I burn through 6000 hours on one of those engines
and have to replace it, I will have considered it money well spent. That's
35 weeks of runtime, and if run my generator a total of 35 weeks before I
die, I will gladly replace the engine. Plus, the smaller twins are quieter,
more fuel efficient, and of course much less expensive.

I also noticed that the output is higher and fuel consumption is lower for
propane. Thanks for the info.

Post by Ron Rosenfeld

Well, you made me go and look at my manual. What I have is the Kohler 12RZ
which has a Ford engine. Obviously a different beast than the one you are
looking at.
But I do note something interesting which you may want to check on yours.
On mine, the rating is significantly higher on LP compared with natural
gas. The natural gas rating on the 12 RZ is 9kW, while the LP rating is 12
kW.
Best,
-- ron (off the grid in Downeast Maine)

Bob M.

2003-09-02 02:38:20 UTC

Well, I have an Onan RS12000 running on NG, and my experience with it could
fill several posts.

Conversion to VAPOR propane would require adding an orifice in the fuel line
and making a carburetor adjustment. Going to LIQUID propane is another
matter and can't be done with this particular unit. It either operates with
vapor fuels or liquid and is made that way at the factory.

The 12kw rating is probably what it's capable of producing with gasoline
fuel. It's rated for 11kw with propane and only 10kw with NG.

The installation manual is incomplete. It presumes you are a Cummins/Onan
employee and have information over and above what's been given to you. A few
phone calls were necessary to find the missing information. The guy who
designed the generator never had to install one, because almost every
electrical connection is either out of sight or too close to the entrance
holes to make them impossible to deal with. I started with #6-3 plus ground
cable in one jacket but had to strip the insulation off and deal with each
conductor separately in order to hook them up at all.

I had a heck of a time finding a plumber to run the NG pipe I needed. My
house already had NG for a furnace and water heater, but eventually they ran
about 35 feet of 1 inch flexible gas line from the meter, with a shutoff at
each end. Then we found out this particular brand of line was not rated for
direct burial, so we had to encase the underground section (about 5 feet)
inside 3 inch PVC pipe which got foamed at each end. Probably would have
been easier to go with black iron for those few feet, however it finally got
done and cost me about $750. I needed to pull a plumbing permit and get it
inspected.

Electrical wiring is straight-forward. I also went with their 100 amp
transfer switch, which is made by GE/Zenith. Had to replace my entire
electrical service after the meter so I could insert the transfer switch
between the new main breaker and a larger/better distribution panel. Got a
good deal on that entire job. I pulled an electrical permit, claiming I did
most of the work, and had no problem with inspection. I also had to add two
additional ground rods outside my house - I guess it's a new code
requirement incase the water company ever goes to plastic pipes.

The biggest shock was finding out that in order to activate the warranty, I
needed to have the unit inspected and started initially by a Cummins/Onan
representative. The nearest office was about 40 miles away. They charge...

are you sitting down???

$85/hour, including travel time, door-to-door,

PLUS -

$1.50 per mile of travel. At 90 miles round trip and about 90 minutes drive
time, just to have them come to my driveway costs $135 + $170 or about $300.
THEN they have to do the inspection and start-up. Now this is something they
could have had the owner do. It's just a detailed checklist which the Onan
guy didn't even check most of the items. In fact, the list was geared to a 1
megawatt diesel unit with water cooling, block heater, etc. They could have
included the list with the installation instructions. Anyway, after clearing
up a short circuit at the transfer panel (I had overtightened a wire clamp
and pinched a wire to ground), the unit was started and voltage and
frequency were measured. We exercised the transfer switch, tried various
loads, and I signed the inspection and startup sheet.

There were other problems involved with the startup process and personnel,
but the end result was that everything worked just fine. I ended up knowing
more about the generator system than the local Onan rep. I also had better
test equipment at my disposal and knew how to use it.

The unit was purchased in October 2001 and finally OKd in January 2002. I
had one power failure in Sept 2002 and it worked just fine for over 90
minutes. Then in Feb 2003 while exercising the unit, I noticed that it
started surging and eventually stalled. This took several months to figure
out, and eventually it came down to a loose ground connection on the
electronic governor. I ended up replacing the governor control module (done
by myself with warranty parts, luckily) before discovering the bad ground,
and had some additional self-inflicted problems at the same time, but other
than that, the unit seemed to run fine during the power problem back in
August 2003 up here in the northeast.

My unit is hard to start in the winter. Sometimes it will crank for 20
seconds, catch, almost, but never come up to 3600 RPM. I finally changed the
factory oil and filter, putting in a synthetic 10W40 which should be a bit
thinner and let the engine start easier in the winter. If this doesn't help,
I'll look into a block heater of some sort. Plenty of battery power, the
engine just doesn't want to gain enough speed when cold. It could also be a
natural gas supply problem, as the pressure at my house runs between 6 and 7
inches WC. The generator manual indicates they want 7 - 11 or 7 - 15 inches,
yet residential service is typically in the 4-7 range, and this unit is
supposed to be for residential use.

Due to problems not discussed here, I refuse to do business with the local
Cummins/Onan reps. I found another rep in the Boston area who was extremely
friendly and helpful. I have dealt with them on a few occasions and was
extremely pleased with their service.

If I had to recommend this unit to someone else, I probably would not, just
due to the startup requirements and cost, and difficulty of installation and
cold weather starting. However, the unit is extremely quiet and does seem to
do the job.

Bob M.
======

Dlehmicke

2003-09-02 03:46:23 UTC

I"d like to add two questions to this discussion:

1. Does the run-of-the-mill generator in the 10kW range produce a waveform
good enough for servers, PCs, and other components of a small IT department?

2. Do I need to worry about balancing the load on a 120/240 generator? Should
I plan on a balancing autotransformer?

zeromedic

2003-09-02 05:35:57 UTC

On 02 Sep 2003 03:46:23 GMT, ***@aol.com (Dlehmicke) wrote:

First, I want to thank Bob M for his observations about dealing with Onan,
they make some good generators, but some of their policies (and dealers)
are just plain stupid.

Post by Dlehmicke
1. Does the run-of-the-mill generator in the 10kW range produce a waveform
good enough for servers, PCs, and other components of a small IT department?

Yes.

There really aren't any "run of the mill" generators at 10 kw. Most anything
you find will likely put out a pretty good sine wave, somewhere close to
120/240 vac, right around 60 Hz.

(btw, computers will run just fine on most any power you throw at them,
they all have switching ps's that first rectify incoming power to dc, then
chop it to high freqency ac before it hits the toroid transformer)

The need for "clean pure power" to run computers is mostly marketing hype.

Some UPS's puke on off-frequency/bad waveform power.

Post by Dlehmicke
2. Do I need to worry about balancing the load on a 120/240 generator? Should
I plan on a balancing autotransformer?

Yes.

If you want to use even half of the generator's output capability, find(measure)
a way to split the actual loads across both sides of its terminals.

Transformers shouldn't be needed unless you Really have to have lots
of current on just 1 120 volt circuit. (better to rewire the genny for 120 only)

Side note: if you split your computer equipment on opposite sides of the
120/240 generator, be very sure to dot your T's/cross your I's about grounding
and bonding the neutral and safety ground conductors. Bond them in ONLY
ONE PLACE.

Easiest to run all the computer equipment on 1 120 circuit, and lights, tv's
vcr's, expresso machines on the other leg.

zero

albown

2003-09-02 15:56:24 UTC

Post by zeromedic
First, I want to thank Bob M for his observations about dealing with Onan,
they make some good generators, but some of their policies (and dealers)
are just plain stupid.

Post by Dlehmicke
1. Does the run-of-the-mill generator in the 10kW range produce a waveform
good enough for servers, PCs, and other components of a small IT department?

Yes.
There really aren't any "run of the mill" generators at 10 kw. Most anything
you find will likely put out a pretty good sine wave, somewhere close to
120/240 vac, right around 60 Hz.
(btw, computers will run just fine on most any power you throw at them,
they all have switching ps's that first rectify incoming power to dc, then
chop it to high freqency ac before it hits the toroid transformer)
The need for "clean pure power" to run computers is mostly marketing hype.

In a nut shell,

Servers on a genny. Lets see every time the gen starts or stops the servers
reboot. I doubt that you have an instant start gen with a soft load
transfer switch. Surely you have UPS's in front of the servers. If your
UPS's are above 1.5 kw and active they will clean up most of issues as a
function of what they do. If you look about the larger UPS's even have
harmonic and voltage controls built in. Smaller UPS's are not active they
are passive. They switch when the power fails.

The need for clean power is not marketing hype. It is a real world
situation. Clean power = low or no harmonics. Rule of thumb >than 10 volts
on the neutral or >than 3 volts on the ground your going to have problems.
Since you are producing your own power, let us discuss only that situation.
Would you run a welder on your genny knowing your servers are being powered?
Probably not. Would you have a laser printer and/or copy machine running on
the same circuits? Maybe, which may or may not be a good idea. I wrote a
spec for a university requiring all new construction to have the laser
printers/copiers on seperate panels fed by isolation transformers. By design
lasers are dirty, one major company even uses zero crossing on the sine wave
as a signal to do processes inside the copier.

Clean power is essentially the ablity of the electrical system to handle
events. All devices with switch mode power supplies do contribute to the
problem. Got any compact floresents or electronic ballasts in your fixtures?
Some of the compact are 100 % harmonic some of the electronic ballasts can
be as high as 20%. Will 1-10 hurt how about 30-50 devices? Who knows it
depends on your electrical system. Start with a good grounding system, less
than 5 ohms to ground, tested at least 4 times during the first year. A dry
month, a wet one and two inbetween. Seperate by isolation transformers all
dirty equipment. Use over sized grounds and neutrals Perferably stranded
(MTW) wire. Balance your loads not by phase but by the generator. Putting
all dirty equipment on one phase is not going to help. All that happens is
the harmonics travels to the winding of the generator and back out the other
phase. Balance the load by how you use the generator. Unbalanced loading on
generators could result in a quicker demise of the generator. Balancing your
utility feed could save you some money as well.

For all your grounding needs check the Soars book on grounding. Ther is a
book for every NEC Code book so read the one that applies to your
installaion. He does a wonder job of explaining a very complex subject.

If your servers are not all that important, then in the words of Emily
Natilla (SNL) " Never Mind"

Post by zeromedic
Some UPS's puke on off-frequency/bad waveform power.

Post by Dlehmicke
2. Do I need to worry about balancing the load on a 120/240 generator?

Should

Post by zeromedic

Post by Dlehmicke
I plan on a balancing autotransformer?

Yes.
If you want to use even half of the generator's output capability, find(measure)
a way to split the actual loads across both sides of its terminals.
Transformers shouldn't be needed unless you Really have to have lots
of current on just 1 120 volt circuit. (better to rewire the genny for 120 only)
Side note: if you split your computer equipment on opposite sides of the
120/240 generator, be very sure to dot your T's/cross your I's about grounding
and bonding the neutral and safety ground conductors. Bond them in ONLY
ONE PLACE.
Easiest to run all the computer equipment on 1 120 circuit, and lights, tv's
vcr's, expresso machines on the other leg.
zero

Steve Spence

2003-09-03 00:57:22 UTC

no, the run of the mill gennie does strange things to our pc's. we use the
gennie for battery charging, and run the servers from battery fed inverters.

there are a couple of gennies that have integrated inverters.
--
Steve Spence
www.green-trust.org

Post by Dlehmicke
1. Does the run-of-the-mill generator in the 10kW range produce a waveform
good enough for servers, PCs, and other components of a small IT department?
2. Do I need to worry about balancing the load on a 120/240 generator?

Should

Post by Dlehmicke
I plan on a balancing autotransformer?

Bruce in Alaska

2003-09-03 04:51:50 UTC

"Run of the Mill" genertor is a piece of junk. Any 3600 Rpm generator
is basically "standby only" system and not made for suppling "Prime
Power". I live far out in the alaskan bush and generate all my own
power. I run servers, gateways, routers, and the like, and am the local
ISP. What you need is a Prime Power Genset. Look for something in the
1800 Rpm range. I have a 15Kw, 4 cyl, 1800 Rpm, water cooled, Onan on a
trailer, that runs on gasoline, but has a NG and Propane conversion Kit
available for it. This is my "Lease Unit" for local Cabin Builders.

I also have a pair of 20Kw Northern Lights diesel Gensets that supply
all my power for the place here. They both were rebuilt 6 years ago,
and had 40,000 Hrs on them when rebuilt. Down at my cabin, I have
two Onan, Single Cyl, 3Kw, 1800 Rpm, Diesel Gensets that supply power
for that place. One is aircooled, and the other is watercooled. They
feed the input of a Trace 2624 Inverter/Charger that powers the place
and all the outbuildings.

I have Load Balancing Transformers installed in all my Powerhouses.
Most of the "Run of the Mill" Gensets are 120/240 Vac and have fixed
wiring, so that they can't be rewired for 120 Vac only. this means that
if you only have a 120 Vac load, you only load half the generator, and
can really only pull 55% of the rated load on one leg. If you put a
240/120 Transformer on the output of the genset where the generator is
feeding 240Vac Single Phase to the Primary, and you parallel the two
Secondary Windings you can pull the Full Rated Power at 120 Vac, and
keep the genset windings happy at the same time. All of my gensets have
6 or 12 lead generators, and can be wired for Full Output 120 Vac Power
or 240 Vac, but I choose to wire them all to transformers and do my
load balancing that way. 240/120 Transformers just aren't that expensive
if you look around enough. I have them in various sizes form 20Kw on
down to 6Kw.

Bruce in alaska

Alan Combellack

2003-09-03 13:05:28 UTC

Bruce,
Clearly you have much experience with electricity generation. Would you
care to hazard an estimate of what a kiloWatt hour costs you?
Alan C

Post by Bruce in Alaska
"Run of the Mill" genertor is a piece of junk. Any 3600 Rpm generator
is basically "standby only" system and not made for suppling "Prime
Power". I live far out in the alaskan bush and generate all my own
power. I run servers, gateways, routers, and the like, and am the local
ISP. What you need is a Prime Power Genset. Look for something in the
1800 Rpm range. I have a 15Kw, 4 cyl, 1800 Rpm, water cooled, Onan on a
trailer, that runs on gasoline, but has a NG and Propane conversion Kit
available for it. This is my "Lease Unit" for local Cabin Builders.
I also have a pair of 20Kw Northern Lights diesel Gensets that supply

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.514 / Virus Database: 312 - Release Date: 28/08/2003

Bruce in Alaska

2003-09-10 21:50:28 UTC

Post by Alan Combellack
Bruce,
Clearly you have much experience with electricity generation. Would you
care to hazard an estimate of what a kiloWatt hour costs you?
Alan C

Well it is really cheap, as I don't pay for any of it out of my pocket,
but those guy's who do pay for my energy, figure it close to $.27/KwHour.
That includes: Maintainance, Fuel, and Consumables. Some of the Local
Utilities are saying $.24/KwHr, but they have mostly switched to Hydro
and use Diesel only for peaking and backup. There is talk about a
Grid being constructed around here, that would tie a bunch of these
small communitie systems together, but nothing substantial as far as Fed
Approval yet. I have never figured what my Cabin costs per Kwhr but it
can't be much asI haven't yet consumed the first 25 Gals of diesel yet.
I did spend $75Us to have the Injector Pump and Injector rebuilt last
winter. When the Genset only burns a cup of fuel per hour, at rated load
it is fairly cheap. Lube Oil and Filters cost more than the fuel for
these smaller gensets. Oil Change Interval is something around 200 hours
for my diesel gensets and 50 hours for the Gasoline powered ones that
don't have Oil filtering. My 15Kw Onan Gasoline Powered Genset is on
the high side of 300 hours between oil changes, but it hasn't had much
use this summer.

Bruce in alaska

b***@zotnet.net

2003-09-11 03:56:18 UTC

Post by Bruce in Alaska
When the Genset only burns a cup of fuel per hour, at rated load
it is fairly cheap. Lube Oil and Filters cost more than the fuel for
these smaller gensets. Oil Change Interval is something around 200 hours
for my diesel gensets and 50 hours for the Gasoline powered ones that
don't have Oil filtering. My 15Kw Onan Gasoline Powered Genset is on
the high side of 300 hours between oil changes, but it hasn't had much
use this summer.
Bruce in alaska

Have you considered rigging a larger oil reservoir to increase the
time between changes for the smaller engines?

b***@zotnet.net

2003-09-12 03:36:06 UTC

Post by b***@zotnet.net
Have you considered rigging a larger oil reservoir to increase the
time between changes for the smaller engines?

I had not even thought of that eventuality for the small ones at all.
It would make them a bit more flexable, but I wonder if it is practical
if there is no oil pump and the engine is "splash oiled". How would the
extra oil tank flow into the base of the engine and circulate the extra
oil?
Bruce in alaska

Recognizing that this may not be worth it...
One could purchase or fabricate an oil tank. A 55-gallon drum could be
one method. By brazing or using bulkhead connections one could make a
couple of connections to the oil pan. Using a small motor driven gear
pump some valves and some good hoses (the whole works mounted on a
containment skid) you could circulate the oil to the pan and back. You
could mount a filter in line to provide a means of keeping the oil
clean.
The engine would still be splash-lubricated but would have a larger
reservoir of oil that would also be filtered. If you figure that 4
quarts lasts 200 hours without filtration then 40 gallons with
filtration ought to last you 8000 hours. Generally, it is the
additives that wear out and the contamination with fuel that breaks
down the oil. These things are dependent on the quantity. If you have
a first class filter and sludge remover system, I see no reason why
you should not get many thousands of hours out of the oil.
When I sailed on large ships, we went years without changing the oil.
We did have excellent centrifuges, and filters to remove the
contamination from the oil.

Scott Nehrbas

2023-11-28 21:17:41 UTC

Post by b***@zotnet.net

Post by b***@zotnet.net
Have you considered rigging a larger oil reservoir to increase the
time between changes for the smaller engines?

I recently addend natural gas to my house and my Onan RS 12000 was running on a giant propane tank that the estate people selling the house had removed. How can I convert my generator to run on the natural gas? Id rather not have a giant propane tank in the yard if I can convert it without too much trouble. Any info would help! thanks

David Lesher

2023-11-29 00:22:46 UTC

{40+ lines of irrelevent text edited out. Why didn't you start wth your
own post vs. replying to an unrelated thread?}

I recently addend natural gas to my house and my Onan RS 12000 was running =
on a giant propane tank that the estate people selling the house had remove=
d. How can I convert my generator to run on the natural gas? Id rather not =
have a giant propane tank in the yard if I can convert it without too much =
trouble. Any info would help! thanks

Ask Onan and others re: conversion kits. The generator will be de-rated
about 15-20%.

--
A host is a host from coast to ***@panix.com
& no one will talk to a host that's close..........................
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Jim Wilkins

2023-11-30 13:01:12 UTC

Ask Onan and others re: conversion kits. The generator will be de-rated
about 15-20%.
-----------------------------

Refrigerators with inverter compressors have lower starting current surges
that reduce the size of the generator or solar inverter required to run
them.
https://forum.solar-electric.com/discussion/354402/fridge-7-amps-vs-2-1-amps

My Alpicool T60 12VDC inverter fridge+freezer draws about 2.5A running and
less than 5A starting. It can also take 24V and is a good match to solar
battery power. It's a hedge against food supply chain shortages that a
grocery store manager told me may last 5-10 years.

Reducing CO2 will force us to make lifestyle changes and lose some of the
high impact convenience we presently enjoy, for example needing to manually
defrost more efficient freezers and line-dry laundry. Much can be done now
to reduce our personal energy consumption instead of just whining, demanding
and blaming others.

Bob M.

2003-09-03 13:26:04 UTC

I agree that for anything over a week's worth of use, 1800 RPM gensets are
the way to go. My Onan RS12000 is only rated for 200 hours use PER YEAR, or
about 8, 24-hour days. Anything over this voids the warranty. This is an
air-cooled two-cylinder 3600 RPM unit and I'd expect some oil usage after
running this long. The unit is fine for the occasional power outage but is
not meant as a prime generating unit.

30 years ago Onan made some very nice 1800 RPM air-cooled units. Sadly, they
are no longer made that way. Air cooling these days is relegated to 3600 RPM
engines. Liquid cooling is used on the 1800 RPM units which are often Ford
or GM car engines. These just loaf along at this speed and can keep it up
almost indefinitely. Similarly diesels are usually run at this speed, if
they're using a direct connection from the engine to the generator. A lot of
RV generators use belt drive and can get away with very strange engine
speeds, but these are usually set to be at the optimum speed/power point for
the engine.

At this size (rated 12kw or more) your choice is more one of fuel than
anything else. I had natural gas already available. I did not want gasoline
due to the storage requirements. Diesel was a possibility but the engines
are a bit more complicated, there is more maintenance required on the system
as a whole, and the fuel storage, while not as volatile, is still a concern.
With the hard starting problem my unit experienced last winter, I almost
considered converting my unit to propane, but that has its own problems when
cold, and the tank has to be outside and protected somewhat. Propane is also
more expensive in my area, and the less you use the more they charge for
tank rental and other items.

Bob M.
======

"Run of the Mill" genertor is a piece of junk. Any 3600 Rpm generator
is basically "standby only" system and not made for suppling "Prime
Power". I live far out in the alaskan bush and generate all my own
power. I run servers, gateways, routers, and the like, and am the local
ISP. What you need is a Prime Power Genset. Look for something in the
1800 Rpm range. I have a 15Kw, 4 cyl, 1800 Rpm, water cooled, Onan on a
trailer, that runs on gasoline, but has a NG and Propane conversion Kit
available for it. This is my "Lease Unit" for local Cabin Builders.
I also have a pair of 20Kw Northern Lights diesel Gensets that supply
all my power for the place here. They both were rebuilt 6 years ago,
and had 40,000 Hrs on them when rebuilt. Down at my cabin, I have
two Onan, Single Cyl, 3Kw, 1800 Rpm, Diesel Gensets that supply power
for that place. One is aircooled, and the other is watercooled. They
feed the input of a Trace 2624 Inverter/Charger that powers the place
and all the outbuildings.
I have Load Balancing Transformers installed in all my Powerhouses.
Most of the "Run of the Mill" Gensets are 120/240 Vac and have fixed
wiring, so that they can't be rewired for 120 Vac only. this means that
if you only have a 120 Vac load, you only load half the generator, and
can really only pull 55% of the rated load on one leg. If you put a
240/120 Transformer on the output of the genset where the generator is
feeding 240Vac Single Phase to the Primary, and you parallel the two
Secondary Windings you can pull the Full Rated Power at 120 Vac, and
keep the genset windings happy at the same time. All of my gensets have
6 or 12 lead generators, and can be wired for Full Output 120 Vac Power
or 240 Vac, but I choose to wire them all to transformers and do my
load balancing that way. 240/120 Transformers just aren't that expensive
if you look around enough. I have them in various sizes form 20Kw on
down to 6Kw.
Bruce in alaska

Dlehmicke

2003-09-03 15:55:37 UTC

I've been contributing on and off, more or less, to this group for about five
years.

I will have to continue to do so many more years to return the help I've
received in the last couple days on this thread.

Thanks to all.

Jeff Neese

2003-09-05 01:36:51 UTC

I was not aware of the limitation on hours per year. Also, I've always
heard that these engines are good for "about 6000" hours before major
service. Is this your understanding?

Post by Bob M.
I agree that for anything over a week's worth of use, 1800 RPM gensets are
the way to go. My Onan RS12000 is only rated for 200 hours use PER YEAR, or
about 8, 24-hour days. Anything over this voids the warranty. This is an
air-cooled two-cylinder 3600 RPM unit and I'd expect some oil usage after
running this long. The unit is fine for the occasional power outage but is
not meant as a prime generating unit.
30 years ago Onan made some very nice 1800 RPM air-cooled units. Sadly, they
are no longer made that way. Air cooling these days is relegated to 3600 RPM
engines. Liquid cooling is used on the 1800 RPM units which are often Ford
or GM car engines. These just loaf along at this speed and can keep it up
almost indefinitely. Similarly diesels are usually run at this speed, if
they're using a direct connection from the engine to the generator. A lot of
RV generators use belt drive and can get away with very strange engine
speeds, but these are usually set to be at the optimum speed/power point for
the engine.
At this size (rated 12kw or more) your choice is more one of fuel than
anything else. I had natural gas already available. I did not want gasoline
due to the storage requirements. Diesel was a possibility but the engines
are a bit more complicated, there is more maintenance required on the system
as a whole, and the fuel storage, while not as volatile, is still a concern.
With the hard starting problem my unit experienced last winter, I almost
considered converting my unit to propane, but that has its own problems when
cold, and the tank has to be outside and protected somewhat. Propane is also
more expensive in my area, and the less you use the more they charge for
tank rental and other items.
Bob M.
======

Post by Dlehmicke
1. Does the run-of-the-mill generator in the 10kW range produce a

waveform

Post by Dlehmicke
good enough for servers, PCs, and other components of a small IT

department?

Post by Dlehmicke
2. Do I need to worry about balancing the load on a 120/240 generator?
Should
I plan on a balancing autotransformer?

"Run of the Mill" genertor is a piece of junk. Any 3600 Rpm generator
is basically "standby only" system and not made for suppling "Prime
Power". I live far out in the alaskan bush and generate all my own
power. I run servers, gateways, routers, and the like, and am the local
ISP. What you need is a Prime Power Genset. Look for something in the
1800 Rpm range. I have a 15Kw, 4 cyl, 1800 Rpm, water cooled, Onan on a
trailer, that runs on gasoline, but has a NG and Propane conversion Kit
available for it. This is my "Lease Unit" for local Cabin Builders.
I also have a pair of 20Kw Northern Lights diesel Gensets that supply
all my power for the place here. They both were rebuilt 6 years ago,
and had 40,000 Hrs on them when rebuilt. Down at my cabin, I have
two Onan, Single Cyl, 3Kw, 1800 Rpm, Diesel Gensets that supply power
for that place. One is aircooled, and the other is watercooled. They
feed the input of a Trace 2624 Inverter/Charger that powers the place
and all the outbuildings.
I have Load Balancing Transformers installed in all my Powerhouses.
Most of the "Run of the Mill" Gensets are 120/240 Vac and have fixed
wiring, so that they can't be rewired for 120 Vac only. this means that
if you only have a 120 Vac load, you only load half the generator, and
can really only pull 55% of the rated load on one leg. If you put a
240/120 Transformer on the output of the genset where the generator is
feeding 240Vac Single Phase to the Primary, and you parallel the two
Secondary Windings you can pull the Full Rated Power at 120 Vac, and
keep the genset windings happy at the same time. All of my gensets have
6 or 12 lead generators, and can be wired for Full Output 120 Vac Power
or 240 Vac, but I choose to wire them all to transformers and do my
load balancing that way. 240/120 Transformers just aren't that expensive
if you look around enough. I have them in various sizes form 20Kw on
down to 6Kw.
Bruce in alaska

Bob M.

2003-09-06 17:35:48 UTC

Actually, the first paragraph of the Mfgr's Limited Warranty states:

"COVERAGE PERIOD
Provided such goods are operated and maintained in accordance with Onan's
written instructions, Onan warrants the RS12000 RESIDENTIAL STANDBY
GENERATOR SET to be free from defects in workmanship and material for a
period of two (2) years or 200 hours per year maximum usage, whichever comes
first, from the date of purchase. ..."

It goes on to say that "The second year of coverage will be limited to parts
only, and does not include labor, travel time and mileage." It also says
that "Initial inspection and initial start-up of the RS12000 RESIDENTIAL
STANDBY GENERATOR SET must be conducted by an authorized Cummins/Onan
distributor, or designated representative."

The next page says:
"POWER SECTION: STANDBY POWER RATING
The standby power rating is applicable for supplying emergency power for the
duratio of normal power interruption. No sustained overload capability is
available for this rating. This rating is applicable to installations served
by a reliable normal utility source. This rating is only applicable to
varying loads with an average load factor of 80% of the standby rating for a
maximum of 200 hours of operation per year. The standby rating is only
applicable for emergency and standby applications where the generator set
serves as the back up to the normal utility source. No sustained utility
parallel operation is permitted with the rating."

This document is dated 1995 and revised 7/99.

I bought the service manual when I first got the unit. The only table in
there shows some maintenance at every 100 hours, 200 hours, and 500 hours. I
don't see anything about major overhauls. It may be in there but 6000
operating hours is probably way past my lifetime.

Bob M.
======

Post by Jeff Neese
I was not aware of the limitation on hours per year. Also, I've always
heard that these engines are good for "about 6000" hours before major
service. Is this your understanding?

Post by Bob M.
I agree that for anything over a week's worth of use, 1800 RPM gensets are
the way to go. My Onan RS12000 is only rated for 200 hours use PER YEAR,

Post by Bob M.
about 8, 24-hour days. Anything over this voids the warranty. This is an
air-cooled two-cylinder 3600 RPM unit and I'd expect some oil usage after
running this long. The unit is fine for the occasional power outage but is
not meant as a prime generating unit.
30 years ago Onan made some very nice 1800 RPM air-cooled units. Sadly,

they

Post by Bob M.
are no longer made that way. Air cooling these days is relegated to 3600

RPM

Post by Bob M.
engines. Liquid cooling is used on the 1800 RPM units which are often Ford
or GM car engines. These just loaf along at this speed and can keep it up
almost indefinitely. Similarly diesels are usually run at this speed, if
they're using a direct connection from the engine to the generator. A

lot

Post by Jeff Neese
of

Post by Bob M.
RV generators use belt drive and can get away with very strange engine
speeds, but these are usually set to be at the optimum speed/power point

for

Post by Bob M.
the engine.
At this size (rated 12kw or more) your choice is more one of fuel than
anything else. I had natural gas already available. I did not want

gasoline

Post by Bob M.
due to the storage requirements. Diesel was a possibility but the engines
are a bit more complicated, there is more maintenance required on the

system

Post by Bob M.
as a whole, and the fuel storage, while not as volatile, is still a

concern.

Post by Bob M.
With the hard starting problem my unit experienced last winter, I almost
considered converting my unit to propane, but that has its own problems

when

Post by Bob M.
cold, and the tank has to be outside and protected somewhat. Propane is

also

Post by Bob M.
more expensive in my area, and the less you use the more they charge for
tank rental and other items.
Bob M.
======

Post by Dlehmicke
1. Does the run-of-the-mill generator in the 10kW range produce a

waveform

Post by Dlehmicke
good enough for servers, PCs, and other components of a small IT

department?

Post by Dlehmicke
2. Do I need to worry about balancing the load on a 120/240

generator?

Post by Dlehmicke
Should
I plan on a balancing autotransformer?

"Run of the Mill" genertor is a piece of junk. Any 3600 Rpm generator
is basically "standby only" system and not made for suppling "Prime
Power". I live far out in the alaskan bush and generate all my own
power. I run servers, gateways, routers, and the like, and am the local
ISP. What you need is a Prime Power Genset. Look for something in the
1800 Rpm range. I have a 15Kw, 4 cyl, 1800 Rpm, water cooled, Onan on a
trailer, that runs on gasoline, but has a NG and Propane conversion Kit
available for it. This is my "Lease Unit" for local Cabin Builders.
I also have a pair of 20Kw Northern Lights diesel Gensets that supply
all my power for the place here. They both were rebuilt 6 years ago,
and had 40,000 Hrs on them when rebuilt. Down at my cabin, I have
two Onan, Single Cyl, 3Kw, 1800 Rpm, Diesel Gensets that supply power
for that place. One is aircooled, and the other is watercooled. They
feed the input of a Trace 2624 Inverter/Charger that powers the place
and all the outbuildings.
I have Load Balancing Transformers installed in all my Powerhouses.
Most of the "Run of the Mill" Gensets are 120/240 Vac and have fixed
wiring, so that they can't be rewired for 120 Vac only. this means that
if you only have a 120 Vac load, you only load half the generator, and
can really only pull 55% of the rated load on one leg. If you put a
240/120 Transformer on the output of the genset where the generator is
feeding 240Vac Single Phase to the Primary, and you parallel the two
Secondary Windings you can pull the Full Rated Power at 120 Vac, and
keep the genset windings happy at the same time. All of my gensets have
6 or 12 lead generators, and can be wired for Full Output 120 Vac Power
or 240 Vac, but I choose to wire them all to transformers and do my
load balancing that way. 240/120 Transformers just aren't that expensive
if you look around enough. I have them in various sizes form 20Kw on
down to 6Kw.
Bruce in alaska

Bob M.

2003-09-03 13:14:35 UTC

In the case of my Onan RS12000, the waveform is very acceptable and is about
5% distortion. The frequency is governed electronically and, for some
reason, Onan set it to 60.4 Hz rather than 60.0 Hz. That means all the
clocks in the house gain time when on the generator. Most annoying to a time
freak like me. The voltage is controlled separately and coming out under no
load it was 118.5 VAC RMS on each side of the line, or 237 VAC RMS across
the lines. The two UPSes at my house: an APC BackUPS-650 and a Best Fortress
650, are quite happy with the power produced by this generator. Likewise,
the TV, computers, washing machine, clothes dryer, refrigerator, air
conditioning compressor, and forced air furnace have no problems.

I didn't bother to balance the loads in my house, and typically it's
something like 10 amps on one side and only 2 on the other. I'm sure the
voltage swings somewhat but not enough to ruin the nice wiring job done by
the electrician. If the load was a lot more unbalanced then I'd reconsider.

Possibly because this generator is externally regulated, it puts out a nice
waveform. I'd expect any unit that's not "portable" to output commercial
utility-quality power, but I wish I could slow mine down a bit and bump the
voltage up to 122 under no load.

If the generator specs don't say low distortion or suitable for sensitive
equipment, or if it is self-regulating, then it may not provide the clean
power we desire.

Bob M.
======

Should

Post by Dlehmicke
I plan on a balancing autotransformer?

Joey

2003-09-07 05:19:12 UTC

I use an APC Matrix 5000, which runs on 240 (or 208), here at home
for the computers and my office (and the 1ton window A/C in the
office). Don't have to worry about load balancing. Just use the
"manual transfer switch" ie plug it into the generator when needed and
it switches a couple times, then locks up with the generator. (A
lesser APC UPS would need to be set to medium or low sensitivity) No
problems even when the A/C cycles, which no is not going thru the UPS!
Nor are the refrigerator or misc lights in the house all of which have
been tested all at once during a hot summer day. Generator is just a
generac 6500. The key here is the 240V UPS.

At my last job we had a generator the size of a llarge SUV and a UPS
of similar girth. 300KVA iirc. We also ran a dozen APC Smart-UPS
2200RMXL's, a couple of Liebert onlines, and a 5ton A/C off of a
trailer genny numerous times before we build that real datacenter in a
new location. Was a 3-phase panel with a manual crash switch and 100'
of entertainment grade cable & tails waiting to go out to a truck.
Just had to check rotation and throw the switch (looking the other way
of course). Only problem we ever had was a blown radiator hose which
fortunately happened about 20 minutes before the power returned. Damn
rentals!

Jeff Neese

2003-09-07 13:56:20 UTC

I also have an APC Matrix 5000. How well does it recharge off the
generator? Also, how many batteries do you have?

Post by Joey
I use an APC Matrix 5000, which runs on 240 (or 208), here at home
for the computers and my office (and the 1ton window A/C in the
office). Don't have to worry about load balancing. Just use the
"manual transfer switch" ie plug it into the generator when needed and
it switches a couple times, then locks up with the generator. (A
lesser APC UPS would need to be set to medium or low sensitivity) No
problems even when the A/C cycles, which no is not going thru the UPS!
Nor are the refrigerator or misc lights in the house all of which have
been tested all at once during a hot summer day. Generator is just a
generac 6500. The key here is the 240V UPS.
At my last job we had a generator the size of a llarge SUV and a UPS
of similar girth. 300KVA iirc. We also ran a dozen APC Smart-UPS
2200RMXL's, a couple of Liebert onlines, and a 5ton A/C off of a
trailer genny numerous times before we build that real datacenter in a
new location. Was a 3-phase panel with a manual crash switch and 100'
of entertainment grade cable & tails waiting to go out to a truck.
Just had to check rotation and throw the switch (looking the other way
of course). Only problem we ever had was a blown radiator hose which
fortunately happened about 20 minutes before the power returned. Damn
rentals!

Should

Post by Dlehmicke
I plan on a balancing autotransformer?

Joey

2003-09-07 22:34:55 UTC

As far as I know, it charges OK.... I've only used it in a few
situations for at most an hour at a time. The unit switches to
line/batt serveral times before the "Auto" setting backs itself off a
low sensitivity. Then it's solid even with things switching on/off
elsewhere on the genny. I would assume the fact it's on line means
that it is charging ok.

Have 3 regular smartcells on it.

Post by Jeff Neese
I also have an APC Matrix 5000. How well does it recharge off the
generator? Also, how many batteries do you have?

Post by Dlehmicke
1. Does the run-of-the-mill generator in the 10kW range produce a

waveform

Post by Dlehmicke
good enough for servers, PCs, and other components of a small IT

department?

Post by Dlehmicke
2. Do I need to worry about balancing the load on a 120/240 generator?

Should

Post by Dlehmicke
I plan on a balancing autotransformer?

Jeff Neese

2003-09-05 01:29:54 UTC

Well, this is exactly the kind of information I'm looking for. I'll have to
read it again, but the first thing that occurs to me is that I may have an
easier time with installation, startup, warranty inspections, etc. because
I'm planning to have a Cummins-Onan guy do the installation. Also, I'm
having gas newly installed and can request a minimum pressure. The Cummins
people here tell me to have it put in with 11 inches.

What would you buy if you had to do it again?

Post by Bob M.
Well, I have an Onan RS12000 running on NG, and my experience with it could
fill several posts.
Conversion to VAPOR propane would require adding an orifice in the fuel line
and making a carburetor adjustment. Going to LIQUID propane is another
matter and can't be done with this particular unit. It either operates with
vapor fuels or liquid and is made that way at the factory.
The 12kw rating is probably what it's capable of producing with gasoline
fuel. It's rated for 11kw with propane and only 10kw with NG.
The installation manual is incomplete. It presumes you are a Cummins/Onan
employee and have information over and above what's been given to you. A few
phone calls were necessary to find the missing information. The guy who
designed the generator never had to install one, because almost every
electrical connection is either out of sight or too close to the entrance
holes to make them impossible to deal with. I started with #6-3 plus ground
cable in one jacket but had to strip the insulation off and deal with each
conductor separately in order to hook them up at all.
I had a heck of a time finding a plumber to run the NG pipe I needed. My
house already had NG for a furnace and water heater, but eventually they ran
about 35 feet of 1 inch flexible gas line from the meter, with a shutoff at
each end. Then we found out this particular brand of line was not rated for
direct burial, so we had to encase the underground section (about 5 feet)
inside 3 inch PVC pipe which got foamed at each end. Probably would have
been easier to go with black iron for those few feet, however it finally got
done and cost me about $750. I needed to pull a plumbing permit and get it
inspected.
Electrical wiring is straight-forward. I also went with their 100 amp
transfer switch, which is made by GE/Zenith. Had to replace my entire
electrical service after the meter so I could insert the transfer switch
between the new main breaker and a larger/better distribution panel. Got a
good deal on that entire job. I pulled an electrical permit, claiming I did
most of the work, and had no problem with inspection. I also had to add two
additional ground rods outside my house - I guess it's a new code
requirement incase the water company ever goes to plastic pipes.
The biggest shock was finding out that in order to activate the warranty, I
needed to have the unit inspected and started initially by a Cummins/Onan
representative. The nearest office was about 40 miles away. They charge...
are you sitting down???
$85/hour, including travel time, door-to-door,
PLUS -
$1.50 per mile of travel. At 90 miles round trip and about 90 minutes drive
time, just to have them come to my driveway costs $135 + $170 or about $300.
THEN they have to do the inspection and start-up. Now this is something they
could have had the owner do. It's just a detailed checklist which the Onan
guy didn't even check most of the items. In fact, the list was geared to a 1
megawatt diesel unit with water cooling, block heater, etc. They could have
included the list with the installation instructions. Anyway, after clearing
up a short circuit at the transfer panel (I had overtightened a wire clamp
and pinched a wire to ground), the unit was started and voltage and
frequency were measured. We exercised the transfer switch, tried various
loads, and I signed the inspection and startup sheet.
There were other problems involved with the startup process and personnel,
but the end result was that everything worked just fine. I ended up knowing
more about the generator system than the local Onan rep. I also had better
test equipment at my disposal and knew how to use it.
The unit was purchased in October 2001 and finally OKd in January 2002. I
had one power failure in Sept 2002 and it worked just fine for over 90
minutes. Then in Feb 2003 while exercising the unit, I noticed that it
started surging and eventually stalled. This took several months to figure
out, and eventually it came down to a loose ground connection on the
electronic governor. I ended up replacing the governor control module (done
by myself with warranty parts, luckily) before discovering the bad ground,
and had some additional self-inflicted problems at the same time, but other
than that, the unit seemed to run fine during the power problem back in
August 2003 up here in the northeast.
My unit is hard to start in the winter. Sometimes it will crank for 20
seconds, catch, almost, but never come up to 3600 RPM. I finally changed the
factory oil and filter, putting in a synthetic 10W40 which should be a bit
thinner and let the engine start easier in the winter. If this doesn't help,
I'll look into a block heater of some sort. Plenty of battery power, the
engine just doesn't want to gain enough speed when cold. It could also be a
natural gas supply problem, as the pressure at my house runs between 6 and 7
inches WC. The generator manual indicates they want 7 - 11 or 7 - 15 inches,
yet residential service is typically in the 4-7 range, and this unit is
supposed to be for residential use.
Due to problems not discussed here, I refuse to do business with the local
Cummins/Onan reps. I found another rep in the Boston area who was extremely
friendly and helpful. I have dealt with them on a few occasions and was
extremely pleased with their service.
If I had to recommend this unit to someone else, I probably would not, just
due to the startup requirements and cost, and difficulty of installation and
cold weather starting. However, the unit is extremely quiet and does seem to
do the job.
Bob M.
======

Post by Jeff Neese
Decided to install a natural-gas stanby generator. I have propane now,

but

Post by Jeff Neese
will am having natural gas run to my house specifically for the generator.
Propane will act as backup fuel (with a simple conversion, of course) so

Post by Jeff Neese
the unlikely event that both electricity and gas go out, I still have

power.

Post by Jeff Neese
Don't need much, just enough to run the well pump, furnace, hot water
heater, and a couple of other key devices like perhaps the refrigerator.
Making sure that an extended outage, especially in winter, doesn't cause

Post by Jeff Neese
to have to leave because I have no heat or water.
Pretty much got it narrowed down to the Onan RS12000 or the Kohler 11RMY,
very similar generators. I've compared specs, researched the engines, and
pretty much now the minor differences. I'm looking for any real-world
experience or advice, about these generators specifically, Onan vs. Kohler
in general, or any other advice that might be helpful.
Thanks in advance.

Bob M.

2003-09-06 16:42:33 UTC

NG was built into the house in 1951, I bought it in 1987 and there were no
gas appliances here, so they had to re-activate it in 1988 for the water
heater. When I replaced my oil furnace with NG nothing else had to be done.
When I added the generator, I needed to increase the meter capacity from 250
to 450 "whatever-they-measure-it-in". I was told that the gas pressure
around here for residential use is 6 inches WC with absolutely no way to
increase it. Doing so would cause everyone else's appliances to go nuts. I'm
about a mile from the local underground pressure regulator. If I were on a
commercial street, then things might be different.

The genset specs call for 7-11 in one place and 7-15 in another. The Boston
Cummins-Onan folks told me they have lots of these RS12000 units in service
on 4 inches WC and they run quite nicely. My winter problem could have been
due to the original factory oil, which was already 4 years old when I got
the unit. Apparently 30W oil gets very thick below freezing, so it's no
surprise that at 10F it was having a hard time. I'm now running AMSOil 10W40
synthetic made especially for NG standby engines. Onan allows synthetic oils
fortunately, and the AMSOil site lists Onan as an approved user.

I would expect installation to take a solid day if you can get everyone on
site with all the stuff they need to do it. That could run into the several
thousand dollar range. I have seen this unit, "installed" for around $9000,
so if the unit costs about half that, the rest is for installation.

I really do not know what I'd go with if I had to do it again. I went more
by the Onan reputation than anything else, and everything else was
comparable and quite similar. Unfortunately it's nearly impossible to talk
to anyone at the Onan factory, and if you're unhappy with service provided
by the Cummins-Onan organization in your area, there's no one higher to go
to. I hope that my experience with the local C-O rep was not an indication
of how the rest of them operate. Fortunately the Boston group was much more
knowledgable and helpful and went way above and beyond the call of duty in
that they let me repair my unit under warranty and just sent me the part on
an exchange basis. Otherwise I would have had to pay a C-O person almost
$300 to come and change a part that takes maybe 10 minutes if you don't know
what you're doing.

Bob M.
======

Post by Jeff Neese
Well, this is exactly the kind of information I'm looking for. I'll have to
read it again, but the first thing that occurs to me is that I may have an
easier time with installation, startup, warranty inspections, etc. because
I'm planning to have a Cummins-Onan guy do the installation. Also, I'm
having gas newly installed and can request a minimum pressure. The Cummins
people here tell me to have it put in with 11 inches.
What would you buy if you had to do it again?

Post by Bob M.
Well, I have an Onan RS12000 running on NG, and my experience with it

could

Post by Bob M.
fill several posts.
Conversion to VAPOR propane would require adding an orifice in the fuel

line

Post by Bob M.
and making a carburetor adjustment. Going to LIQUID propane is another
matter and can't be done with this particular unit. It either operates

with

Post by Bob M.
vapor fuels or liquid and is made that way at the factory.
The 12kw rating is probably what it's capable of producing with gasoline
fuel. It's rated for 11kw with propane and only 10kw with NG.
The installation manual is incomplete. It presumes you are a

Cummins/Onan

Post by Bob M.
employee and have information over and above what's been given to you. A

few

Post by Bob M.
phone calls were necessary to find the missing information. The guy who
designed the generator never had to install one, because almost every
electrical connection is either out of sight or too close to the entrance
holes to make them impossible to deal with. I started with #6-3 plus

ground

Post by Bob M.
cable in one jacket but had to strip the insulation off and deal with each
conductor separately in order to hook them up at all.
I had a heck of a time finding a plumber to run the NG pipe I needed. My
house already had NG for a furnace and water heater, but eventually they

ran

Post by Bob M.
about 35 feet of 1 inch flexible gas line from the meter, with a shutoff

Post by Bob M.
each end. Then we found out this particular brand of line was not rated

for

Post by Bob M.
direct burial, so we had to encase the underground section (about 5 feet)
inside 3 inch PVC pipe which got foamed at each end. Probably would have
been easier to go with black iron for those few feet, however it finally

got

Post by Bob M.
done and cost me about $750. I needed to pull a plumbing permit and get it
inspected.
Electrical wiring is straight-forward. I also went with their 100 amp
transfer switch, which is made by GE/Zenith. Had to replace my entire
electrical service after the meter so I could insert the transfer switch
between the new main breaker and a larger/better distribution panel. Got a
good deal on that entire job. I pulled an electrical permit, claiming I

did

Post by Bob M.
most of the work, and had no problem with inspection. I also had to add

two

Post by Bob M.
additional ground rods outside my house - I guess it's a new code
requirement incase the water company ever goes to plastic pipes.
The biggest shock was finding out that in order to activate the

warranty,

Post by Jeff Neese
I

Post by Bob M.
needed to have the unit inspected and started initially by a

Cummins/Onan

Post by Bob M.
representative. The nearest office was about 40 miles away. They charge...
are you sitting down???
$85/hour, including travel time, door-to-door,
PLUS -
$1.50 per mile of travel. At 90 miles round trip and about 90 minutes

drive

Post by Bob M.
time, just to have them come to my driveway costs $135 + $170 or about

$300.

Post by Bob M.
THEN they have to do the inspection and start-up. Now this is something

they

Post by Bob M.
could have had the owner do. It's just a detailed checklist which the Onan
guy didn't even check most of the items. In fact, the list was geared to

Post by Jeff Neese
1

Post by Bob M.
megawatt diesel unit with water cooling, block heater, etc. They could

have

Post by Bob M.
included the list with the installation instructions. Anyway, after

clearing

Post by Bob M.
up a short circuit at the transfer panel (I had overtightened a wire clamp
and pinched a wire to ground), the unit was started and voltage and
frequency were measured. We exercised the transfer switch, tried various
loads, and I signed the inspection and startup sheet.
There were other problems involved with the startup process and personnel,
but the end result was that everything worked just fine. I ended up

knowing

Post by Bob M.
more about the generator system than the local Onan rep. I also had better
test equipment at my disposal and knew how to use it.
The unit was purchased in October 2001 and finally OKd in January 2002. I
had one power failure in Sept 2002 and it worked just fine for over 90
minutes. Then in Feb 2003 while exercising the unit, I noticed that it
started surging and eventually stalled. This took several months to figure
out, and eventually it came down to a loose ground connection on the
electronic governor. I ended up replacing the governor control module

(done

Post by Bob M.
by myself with warranty parts, luckily) before discovering the bad ground,
and had some additional self-inflicted problems at the same time, but

other

Post by Bob M.
than that, the unit seemed to run fine during the power problem back in
August 2003 up here in the northeast.
My unit is hard to start in the winter. Sometimes it will crank for 20
seconds, catch, almost, but never come up to 3600 RPM. I finally changed

the

Post by Bob M.
factory oil and filter, putting in a synthetic 10W40 which should be a bit
thinner and let the engine start easier in the winter. If this doesn't

help,

Post by Bob M.
I'll look into a block heater of some sort. Plenty of battery power, the
engine just doesn't want to gain enough speed when cold. It could also

Post by Jeff Neese
a

Post by Bob M.
natural gas supply problem, as the pressure at my house runs between 6

and

Post by Jeff Neese
7

Post by Bob M.
inches WC. The generator manual indicates they want 7 - 11 or 7 - 15

inches,

Post by Bob M.
yet residential service is typically in the 4-7 range, and this unit is
supposed to be for residential use.
Due to problems not discussed here, I refuse to do business with the local
Cummins/Onan reps. I found another rep in the Boston area who was

extremely

Post by Bob M.
friendly and helpful. I have dealt with them on a few occasions and was
extremely pleased with their service.
If I had to recommend this unit to someone else, I probably would not,

just

Post by Bob M.
due to the startup requirements and cost, and difficulty of installation

and

Post by Bob M.
cold weather starting. However, the unit is extremely quiet and does

seem

Post by Jeff Neese
to

Post by Bob M.
do the job.
Bob M.
======

Post by Jeff Neese
Decided to install a natural-gas stanby generator. I have propane now,

but

Post by Jeff Neese
will am having natural gas run to my house specifically for the

generator.

Post by Jeff Neese
Propane will act as backup fuel (with a simple conversion, of course) so

Post by Jeff Neese
the unlikely event that both electricity and gas go out, I still have

power.

Post by Jeff Neese
Don't need much, just enough to run the well pump, furnace, hot water
heater, and a couple of other key devices like perhaps the

refrigerator.

Post by Jeff Neese
Making sure that an extended outage, especially in winter, doesn't cause

Post by Jeff Neese
to have to leave because I have no heat or water.
Pretty much got it narrowed down to the Onan RS12000 or the Kohler

11RMY,

Post by Jeff Neese
very similar generators. I've compared specs, researched the engines,

and

Post by Jeff Neese
pretty much now the minor differences. I'm looking for any real-world
experience or advice, about these generators specifically, Onan vs.

Kohler

Post by Jeff Neese
in general, or any other advice that might be helpful.
Thanks in advance.

Jeff Neese

2003-09-06 12:28:17 UTC

I talked to my local Cummins distributor here in Michigan, Cummins
Bridgeway. A couple of things I learned:

They definitely want at least 7 in of pressure for natural gas. I'll bet
that's part of your problem with hard starting in winter.

They also require an on-site inspection, which is about 4 hours and they
will give me a walkthrough of everything and answer any questions I might
have. $450, which is steep but probably worth it if I'm going to maintain
this thing and be able to troubleshoot problems.

They want to sell me a 5-year warranty for $550, which I think I'll go for.
He told me there are no restrictions on hours per year, but that the 5-year
warranty has a cap of 2000 hours.

I think I've got a good contractor picked out for installation. Recommeded
by Cummins, and after talking to him it sounds like he knows what he's doing
and seems to pride himself in the quality of his installations.

The ticket for the whole thing is more than I bargained for - at least $8500
complete, with the Onan RS12000.

Post by Jeff Neese
Decided to install a natural-gas stanby generator. I have propane now,

but

Post by Jeff Neese
will am having natural gas run to my house specifically for the generator.
Propane will act as backup fuel (with a simple conversion, of course) so

Post by Jeff Neese
the unlikely event that both electricity and gas go out, I still have

power.

Bob M.

2003-09-06 17:59:48 UTC

The gas pressure certainly should be 7 or more, but it will work, once
started, with a bit less.

There's no way the startup and inspection can take 4 hours, unless they
load-test the unit. When I called to set up the appointment, they indicated
that a load test would take an additional 4 hours. All of this is probably
useful and necessary for a 1 megawatt unit, but not something as small as
the RS12000. The guy who came to check mine looked the installation over,
went to install the battery but found I had already done that, went to hook
up the gas but found I had already done that, checked out the wiring
junction panel and found that I had already connected everything, so he had
almost nothing to do. Then he started the unit locally (I had done that just
to make sure it would start before calling him out) and shut it off, then
went inside and did the same thing from the transfer switch. That's when we
found the first problem of a shorted 120VAC wire. That got cleared with some
electrical tape, but the unit still indicated a fault. <let's leave all of
that out for now> Suffice it to say that I repeated the same tests a few
days later and everything ran just fine. Eventually the same person came
back out to finish the startup, measured the voltage and frequency, made
sure the transfer switch did all of its functions in the correct order and
within the required time frame, he filled out a ten-page inspection form,
much of which was geared to a large liquid-cooled installation, and left.
Total time for two trips was perhaps 1-1/2 hours actually at my house.

Due to circumstances which were not specified here, I was never offered an
extended warranty nor did I ask for one. In a way I'm glad I didn't because
for me the expensive part is just getting the service person to my house and
back - the parts are relatively inexpensive. To date, I've replaced the oil
and filter (if you do that yourself, get a thin cookie sheet and drain the
oil into that rather than depending on the rubber drain hose), and replaced
the governor control module, however that problem was eventually traced to a
bad ground connection that only was loose when the engine got hot. During
that repair I decided, on my own, to replace the ignition coil's condenser,
and in the process I snapped a nut off the ignition coil, so I replaced the
coil as well. I was able to repair the original coil, and neither component
was actually bad - I just didn't like the rusty look of the condenser. Also
the unit only has about 12 hours of run time on it in about 1-3/4 years.

For me, the installation was divided into electrical and plumbing. Cost me
$750 to get a plumber to run the NG pipe to the generator. I actually
contacted 9 plumbers, 3 of which returned my call and actually came out to
see the job, and one actually sent me a quote for over $1200. In desperation
I called the gas company and they gave me the name of one of their contract
plumbers who came right out on-time, gave me an estimate, and did the job in
two half-days, starting that morning.

I contacted an electrician and told him what I wanted to do and he agreed to
do the difficult stuff. I pulled the permit and bought a new main disconnect
and a new distribution panel and all the circuit breakers and wire and
conduit needed to connect to the genset. A friend and I ran the conduit and
wired up the outside disconnect and ran the wires into the genset and hooked
them up. We also added two new ground rods outside the house, as requested
by the electrical inspector. The electrician came, pulled the meter, and I
fired up my previous standby generator to provide work light in the
basement. We pulled and labelled all the armored cable from the old box,
then my friend and I put up new plywood on the wall as the electrician ran
new wire from the outside meter into the house. He then mounted and wired
the main disconnect, transfer switch, and distribution panel. The only thing
I had to do was connect the generator control wires to the transfer switch.
The job took about 5 hours and the electrician charged me a ridiculously low
$160. I'd have happily paid twice that, but that was all he wanted.

Electrical and plumbing inspections went without a hitch.

I was lucky to find the generator for about $2800. In fact, the transfer
switch and shipping of everything brought the total cost from that vendor to
just under $4000. The biggest problem was seeing a 60 foot long
tractor-trailer drive down my tiny residential street with absolutely no way
to get this 600 pound generator down to the ground six feet lower than the
bed of the truck. Someone neglected to tell the shipping company it was a
residential delivery, even though I paid extra for it and it was on the
invoice. So we found a way to slide it down into the back of my pick-up
truck, then slid it down to the ground in my back yard. I do NOT recommend
moving it in this manner. One thing they do not tell you on the outside of
the box is that the engine is shipped FULL OF OIL and you do not want to
stand it up on any surface but the normal crated bottom. It would have been
much easier to ship it empty and supply the oil separately, then it could
safely be stood up on any end without having had to worry about the dripping
oil.

Bob M.
======

Post by Jeff Neese
I talked to my local Cummins distributor here in Michigan, Cummins
They definitely want at least 7 in of pressure for natural gas. I'll bet
that's part of your problem with hard starting in winter.
They also require an on-site inspection, which is about 4 hours and they
will give me a walkthrough of everything and answer any questions I might
have. $450, which is steep but probably worth it if I'm going to maintain
this thing and be able to troubleshoot problems.
They want to sell me a 5-year warranty for $550, which I think I'll go for.
He told me there are no restrictions on hours per year, but that the 5-year
warranty has a cap of 2000 hours.
I think I've got a good contractor picked out for installation.

Recommeded

Post by Jeff Neese
by Cummins, and after talking to him it sounds like he knows what he's doing
and seems to pride himself in the quality of his installations.
The ticket for the whole thing is more than I bargained for - at least $8500
complete, with the Onan RS12000.

Post by Bob M.
Well, I have an Onan RS12000 running on NG, and my experience with it

could

Post by Bob M.
fill several posts.
Conversion to VAPOR propane would require adding an orifice in the fuel

line

Post by Bob M.
and making a carburetor adjustment. Going to LIQUID propane is another
matter and can't be done with this particular unit. It either operates

with

Cummins/Onan

Post by Bob M.
employee and have information over and above what's been given to you. A

few

ground

ran

Post by Bob M.
about 35 feet of 1 inch flexible gas line from the meter, with a shutoff

Post by Bob M.
each end. Then we found out this particular brand of line was not rated

for

got

did

Post by Bob M.
most of the work, and had no problem with inspection. I also had to add

two

warranty,

Post by Jeff Neese
I

Post by Bob M.
needed to have the unit inspected and started initially by a

Cummins/Onan

drive

Post by Bob M.
time, just to have them come to my driveway costs $135 + $170 or about

$300.

Post by Bob M.
THEN they have to do the inspection and start-up. Now this is something

they

Post by Bob M.
could have had the owner do. It's just a detailed checklist which the Onan
guy didn't even check most of the items. In fact, the list was geared to

Post by Jeff Neese
1

Post by Bob M.
megawatt diesel unit with water cooling, block heater, etc. They could

have

Post by Bob M.
included the list with the installation instructions. Anyway, after

clearing

knowing

(done

Post by Bob M.
by myself with warranty parts, luckily) before discovering the bad ground,
and had some additional self-inflicted problems at the same time, but

other

the

Post by Bob M.
factory oil and filter, putting in a synthetic 10W40 which should be a bit
thinner and let the engine start easier in the winter. If this doesn't

help,

Post by Bob M.
I'll look into a block heater of some sort. Plenty of battery power, the
engine just doesn't want to gain enough speed when cold. It could also

Post by Jeff Neese
a

Post by Bob M.
natural gas supply problem, as the pressure at my house runs between 6

and

Post by Jeff Neese
7

Post by Bob M.
inches WC. The generator manual indicates they want 7 - 11 or 7 - 15

inches,

extremely

Post by Bob M.
friendly and helpful. I have dealt with them on a few occasions and was
extremely pleased with their service.
If I had to recommend this unit to someone else, I probably would not,

just

Post by Bob M.
due to the startup requirements and cost, and difficulty of installation

and

Post by Bob M.
cold weather starting. However, the unit is extremely quiet and does

seem

Post by Jeff Neese
to

Post by Bob M.
do the job.
Bob M.
======

Post by Jeff Neese
Decided to install a natural-gas stanby generator. I have propane now,

but

Post by Jeff Neese
will am having natural gas run to my house specifically for the

generator.

Post by Jeff Neese
Propane will act as backup fuel (with a simple conversion, of course) so

Post by Jeff Neese
the unlikely event that both electricity and gas go out, I still have

power.

Post by Jeff Neese
Don't need much, just enough to run the well pump, furnace, hot water
heater, and a couple of other key devices like perhaps the

refrigerator.

Post by Jeff Neese
Making sure that an extended outage, especially in winter, doesn't cause

Post by Jeff Neese
to have to leave because I have no heat or water.
Pretty much got it narrowed down to the Onan RS12000 or the Kohler

11RMY,

Post by Jeff Neese
very similar generators. I've compared specs, researched the engines,

and

Post by Jeff Neese
pretty much now the minor differences. I'm looking for any real-world
experience or advice, about these generators specifically, Onan vs.

Kohler