mcron
Ok, new user, first post. Everyone RUN! :)

First off, I am not a typical user. We live off grid and while the generator is backup to the solar system, it does get a lot of use in the winter since we don't have a lot of sun. Our current generator is a the 15kW Generac with the 1.5L Mitsu engine running on Propane. I just turned 10,000 hours with it (yes you read that right) and it is running good still at this time. I don't know how much longer I can count on it, and am starting to look at options.

First option is to get the engine rebuilt, or get a re-manufactured one. From what I have gathered this is really not an option as Generac was the sole source for these and parts are horrible.

Second option would be to replace the engine with another one of similar size that would bolt into the genset. I am not sure how viable this would be, but I thought I would throw it out there.

Third would be to replace it with another one, probably a air cooled 10kW to 14kW model. These engines I can repair and or replace much easier than the Mitsu engine, but then I get concerned about the quality of the genset itself. The 15kW is overkill for what we need. Purchased to get to one that is quieter (1800rpm vs 3600) and would last longer.

Discussion??

-Mark
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Ira
Isn't it kind of a rule of thumb that the air-cooled genset engines have a life expectancy of around 3K hours, whereas the liquid-cooled engines are around 10K hours?

Ira
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d11gnccer
[url]http://www.generac.com/Residential/EcoGen_Series/Product/6kW/[/url]

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mcron
Ira, as a general rule I would agree. Air cooled do not last as long, but they are not as expensive either.

I don't believe that a 6kW would work well. I have a 4.5kW one that I use as backup and it can barely keep up running full out. The current one runs about 1/3 to 1/2 of capacity (guesstimate) if I turn on my air compressor.

My other concern that I did not mention is the cold and starting. Not uncommon here for -30+ temps for weeks, and I would need reliable starting during that.

ETA: d11 I should not have dismissed that selection so readily. On looking at the specs it might work. It can be hooked up for the full 50A at 110v. I currently draw 35A at 110v, but the way they hooked it up (I did NOT do this work) is to take the two 110 circuits from the generator, combine them to 220v, run them through a converter back to 110v to the charge controller. That would eliminate one of my pet peeves on how this was done. It *should* have enough reserve to start my air compressor when it is running a charge. This would come back to the being able to maintain question as it would appear from the brochure that Generac is the sole source for this engine.
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Ira
In your scenario, it seems like the deciding factor between liquid-cooled and air-cooled is that you want something in the 10kW to 14kW range, and that's pretty much non-existent in a liquid-cooled model.

But...if a person was comparing Generac's 20kW air-cooled with their 22kW liquid-cooled, life expectancy of the genset becomes pretty important in the cost analysis. A 22kW is a little more than twice the cost of a 20kW (from Ziller), but it puts out 10% more power, isn't de-rated for NG, runs quieter (1800 rpm vs. 3600 rpm), uses about the same amount of fuel at a given output, but [I]theoretically[/I] lasts three times longer. Depending on maintenance costs, warranties, etc., the 22kW becomes price competitive with the 20kW when comparing the total cost of ownership.
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jmct
The other off grid guy

I am a newbie also, but one of the other off-grid guys, so I thought my two cents might be worth, well, two cents...:)

My off-grid house/shop, aka "barndominium", is in construction so the inverter/charger is brand-new, and I started with the inverter/charger, solar panels, and small battery bank (no generator!) and ran that way all summer with the RV plugged in, sometimes running the AC, and still could run my air compressor and power tools with no problem. I've got 5.5kW of panels and the inv/charger is rated at 6kW. As long as the sun is shining, I've got plenty of juice.

When winter rolled around and reduced my sunlight, I first wired up a 6kw portable "chinese" 3600rpm gasoline unit I had laying around. If I sucked my batteries dry I'd jog around back and "manually" start this little "backup" generator. Note that when this generator starts up I have my inverter/charger programmed to sense the AC "is there" and use that AC to charge the batteries, which at the same time is putting DC on the battery bus, which is being inverted to satisfy whatever AC loads are present. In other words, my AC loads are *always* thru the inverter, never directly from the generator.

My suggestion is to add a fourth option to your list: upgrade to a bigger inverter/charger at the same time you install a replacement generator, and size that new generator smaller and quieter, and supply all of your AC loads thru the inverter.

Probably when you first put your system in, bigger inverter/chargers either didn't exist or were really expensive, and many of the smaller inverters had an automatic bypass that would shed your AC loads directly to the generator AC whenever the AC was present. It was the way to go at the time, but this newer equipment has really surprised me with what it can handle and how clean the power is. For example, I was initially concerned about using the chinese generator because I knew it produced really crappy AC and I didn't want to fry a $3500 inverter/charger, but I finally relented and sure enough the inv/charger chews on that crappy AC, charges the batteries, and I can run LCD tv's and drill battery chargers from the inverted AC without any concerns.

The chinese generator lasted a whopping ~50 hours in this service before the rear bearing cratered, which is why I got started on getting my 1998 Generac 15kw 1.6LFiat LP genset going, which is how I wound up on this forum. Running but not generating voltage yet, but this forum has been key to figuring out what is wrong.

Like you, the 15kw is overkill, but I like the 1800 RPM and it is significantly quieter than the little chinese monster. I am curious about Generac's new "made for off-grid" 2600RPM unit. At 6kw, it looks like they sized it right along the same thinking as my option 4 suggestion above...
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ohmslaw
I have installed the Eco Gen 6kw in an off grid installation. I really like the unit.
The decibel level is great. The unit I installed is in a ten foot square block building and I can work on the system with it running and talk on my blue-tooth headset. Awesome. We put about 300 hours on it in a little over a month. There is a battery capacity issue and the snow has really limited the solar output. I also have the 22 KW 1800 rpm unit at my house and that is a great unit also.
Tim
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ohmslaw
The ECO-Gen is connected to a Magnum inverter and it sends A/C to the house and uses the rest of the power to charge the batteries.

Tim
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mcron
Well I did not design or install the system, but know enough now to know that there were some things done that are not quite right. Overall it works. I have the Trace 5548 inverter (48v, 5.5kW), with a pretty good size battery bank. Voltage to the house goes through the inverter, not shunted. The compressor is large, and will not start if I try it in the house. I am not sure if I tried it when the generator was running, so maybe I will do that as a test. It will kill my 4.5kW genset as well. I don't know what it needs for startup, but it is a whopper. I might be better off to sell it and get a smaller one, but I run impact tools from it and a lot of the smaller ones won't.

I may have to re-think the whole inverter thing though. The goal is to get to a point where the gen runs even very little in the winter. For that we need to go with wind, but that is outside of the discussion here.

I like the thought of the the EcoGen at 6kW, but again, concerned about how long they last and ability to get a new engine and/or parts. From reading the literature it appears that they are another sole source engine. Less fuel consumption is a big draw though. Right now we go through about 1.5gal/hour on Propane. I was discussing this again with my wife, and if I could get a new engine replacement or rebuild I probably would go that route.

Thanks for the discussion. :)

-Mark
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