diesel gensets

[turbodieselfreak]

Anyone here own one of the 12-20kw generators powered by the detroit 2-71? I've decided to go with a transfer switch that will allow whole house power and would like to have central a/c, so my subaru portable ain't gonna cut it anymore. I have a smaller house, so I'm thinking one of the detroits should be plenty for my needs during power outages. What are the weak spots with these engines?

 

[Cup of Joe]

You may not need anything that big actually. My house is all electric and I will be running my AC etc off a 7kw portable generator using a manual transfer switch. I have already discussed the situation with 2 electricians and they both say there is no issues running my AC with this unit. The only issue with only 7kw is if the ac and water heater kick on at the same time it may trip a breaker on the unit. For my house optimum power output would be around 9kw if I was buying a new unit.

FYI a manual transfer switch is only $400 with installation. Automatic cost quite a bit more as does the standby generator.

 

[boraticus]

I own a 7KW Kubota diesel power plant that I use at my camp. It's been running flawlessly for 27 years. Oil changes, fuel conditioner in the fuel every so often and air filters. That's all. It's got close to 5800 hours on it now and isn't showing any signs of slowing down. Burns about 1 litre per hour with a 4000 watt load on it and will burn 1.4 litres/hr. at close to full load.

Why do you think you need that much power and why would you choose that particular diesel? That unit will burn a lot of fuel!

Check these guys out and look at their Kubota gensets. They're very reasonably priced as well.

http://www.generatorsales.com/diesel-generators.asp

 

[Cup of Joe]

I'm a diesel fan but the cost of a 7kw kubota generator is considerable compared to a gas equivalent. My portable was right at $1000 with tax. If you don't like messing with gas you can add a kit to run propane or natural gas for $200.

 

[boraticus]

Originally Posted By: TaterandNoodles
I'm a diesel fan but the cost of a 7kw kubota generator is considerable compared to a gas equivalent. My portable was right at $1000 with tax. If you don't like messing with gas you can add a kit to run propane or natural gas for $200.


Cost is relative. I paid around $5000.00 for the Kubota 27 years ago. Lots of money for sure. But divide the five grand by 27 years and you get an annual cost of $185.00/yr. for the use of a stone axe reliable, fuel efficient power plant. That's a pretty decent return on the money.

If you only need it for occasional back up, any power source will do. if you plan on "using" the machine as I have, shell out the bucks for a high quality, low rpm diesel and it will pay for itself in the long run.

 

[marco246]

I second boraticus. A liquid-cooled, low-rpm diesel is the way to go if you can afford it. I live off the grid and rely on a Northern Lights 6 KW diesel genset as my back-up power source. Primary is solar; secondary is hydro. Back-up to the back-up is a Generac 7KW gasoline genset. Bought the NL new 8 years ago, and it now has 6000 or so hours on it. At 5000 hours I adjusted the valves and changed the fanbelt. Otherwise just change the filters and oil periodically and replace the brushes once in a while. The Generac with 475 hours on it has cost me more to keep running than the NL.

 

[boraticus]

yeah, I forgot to mention that I changed a fan belt and the coolant once on my Kubota.

What diesel do you have on the NL genset? What's your fuel consumption like at say 4kw load and a close to full load?

 

[Cup of Joe]

Originally Posted By: marco246
I second boraticus. A liquid-cooled, low-rpm diesel is the way to go if you can afford it. I live off the grid and rely on a Northern Lights 6 KW diesel genset as my back-up power source. Primary is solar; secondary is hydro. Back-up to the back-up is a Generac 7KW gasoline genset. Bought the NL new 8 years ago, and it now has 6000 or so hours on it. At 5000 hours I adjusted the valves and changed the fanbelt. Otherwise just change the filters and oil periodically and replace the brushes once in a while. The Generac with 475 hours on it has cost me more to keep running than the NL.


I have a generac 7KW, 12250 surge myself. The gasser may cost me more per hour but being used for outages only it is going to take me years to get to 475 hours. It just doesn't come out cost effective for someone on the grid that is only using it for backup power during outages IMO. You and boraticus are getting your moneys worth by racking up thousands of hours of use. I've put roughly 100 hours on my Generac in the last 6.5 years, with a little TLC it could easily last another 13 years. Other then fuel and an oil change I have not done anything to my Generac. The original battery is still is fantastic shape.

To me it sounds like the OP is looking for something more like a Guardian standby unit which still cost allot less then a new diesel unit and can use an automatic transfer switch for seamless starts. If your usage hours are going to be low it just makes more sense. My longest power outage last year was 90 minutes.

http://www.homepowersystems.net/

 

[turbodieselfreak]

Originally Posted By: boraticus
I own a 7KW Kubota diesel power plant that I use at my camp. It's been running flawlessly for 27 years. Oil changes, fuel conditioner in the fuel every so often and air filters. That's all. It's got close to 5800 hours on it now and isn't showing any signs of slowing down. Burns about 1 litre per hour with a 4000 watt load on it and will burn 1.4 litres/hr. at close to full load.

Why do you think you need that much power and why would you choose that particular diesel? That unit will burn a lot of fuel!

Check these guys out and look at their Kubota gensets. They're very reasonably priced as well.

http://www.generatorsales.com/diesel-generators.asp
I'm worried about surge wattage with motors, especially if the well pump, sump, and central air kick in at the same time-very unlikely, but could happen. My understanding (correct me if I'm wrong), is that these motors can burn up quicker than you can shut them down if the voltage/amperage drops below what they require, and none of the above is cheap. In any case, my subaru peaks at 6000 watts, so it's out of the picture no matter what for my intentions. From what I've read, the 2-71's I've checked out were designed for 40,000 hours and are easily rebuildable-could be bull feces, just what I've read. I've considered the NG home standby units, but the longest outage in severe weather here lasted 9 or 10 days, can't imagine what the utility bill would be in a case like that. At my loads, I figure the 2-71 would burn between 1/2 gallon to .75 gph, and I would use it between 3 and 8 hours during a workday, more if I'm off. I've also considered that in times of disaster or civil unrest, my natural gas supply might be disrupted. I figure if I can't get diesel from the pump, I can at least siphon from my truck for powering absolute necessities on a must have basis (truck usually kept 3/4 to full). I have also been told the 2-71 is very tolerant of fuel quality/svo/filtered wvo compared to other designs, if the need arises. I will be purchasing manual transfer switches, which my electrician buddy will hook up for the cost of beer. Sorry for the long response, just trying to explain my reasoning behind my possible choice and intent to cover as many bases as possible. I've been pricing all over the place, and reconditioned and warrantied sets seem to be priced for a few hundred to $1k more than the 7kw units mentioned. Appreciate all the responses guys, keep 'em coming.

 

[turbodieselfreak]

P.S.-just bought my first lazy boy today with heat and massage features. Let's just say this is now on the electrical load necessity list.

 

[JTK]

Originally Posted By: turbodieselfreak
Anyone here own one of the 12-20kw generators powered by the detroit 2-71?


You could probably power the neighborhood w/ one of those babies:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=192

Small portable diesels sure have come down in price however:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98391

Joel

 

[Cup of Joe]

Originally Posted By: turbodieselfreak
At my loads, I figure the 2-71 would burn between 1/2 gallon to .75 gph, and I would use it between 3 and 8 hours during a workday, more if I'm off.


Does that mean its going to see use outside of power outages? If so that is totally different and a diesel genset makes much more sense. If it was only for outages of upto 10 days at a time your total yearly usage might be 300 hours if you get a 10 day outage every year and pick up another 60 hours throughout the year. At that rate it would take you 130 years to reach your 40k hour rebuild mark.

 

[Cup of Joe]

Originally Posted By: turbodieselfreak
I'm worried about surge wattage with motors, especially if the well pump, sump, and central air kick in at the same time-very unlikely, but could happen.


I wanted to add not all generators are equal. My 7kw generac is rated for 7kw continuous but has over 12kw surge.

 

[marco246]

Originally Posted By: boraticus


yeah, I forgot to mention that I changed a fan belt and the coolant once on my Kubota.

What diesel do you have on the NL genset? What's your fuel consumption like at say 4kw load and a close to full load?


boraticus,

The engine is a Japanese-built Shibaura, 0.7L, 3-cylinder unit. It uses 0.4 gallons at full load. It mostly operates near there, since its AC power goes to a Trace inverter which sends 120V directly to the house and inverts the remainder to DC and sends it to storage in a 48V battery bank. The bank stores 420 Ah. The inverter is programmed to start the generator automatically when the power in the bank falls below certain voltages for certain periods of time, e.g., below 48V for two hours.

In my enthusiasm I also forgot I replaced the thermostat (needed) and the injectors (not needed).

 

[turbodieselfreak]

Originally Posted By: JTK
Originally Posted By: turbodieselfreak
Anyone here own one of the 12-20kw generators powered by the detroit 2-71?


You could probably power the neighborhood w/ one of those babies:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=192

Small portable diesels sure have come down in price however:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98391

Joel





OK, so you've got me thinking 12,000 watts is max for the house, I might even take a peak at the 10kw units. I've looked at lesser units than the 2-71 from onan and a few others powered by four stroke non-turbo four pots, but they're quite a bit pricier even used. I figure the a/c will take about 9000 watts surge for starting both the unit and blower, and if I happen to need water or have another heavy appliance going, I want some breathing room. With my subaru, the well pump really bogs down the engine. I love harbor freight for the little stuff, but I'm just not sold on chinese engines yet, gas or diesel.

 

[boraticus]

9000 watts! Something don't sound right there. Are these 120 volt appliances?

Anything drawing that much at start up should be changed over to 240 volts. That will cut your amperage by half. Much easier on the genset. I have a water pump at camp that is convertible from 120 to 240. I switched it from standard setting of 120 volts (50 amp surge draw) to 240 volts and now it's surge is around half of that.

 

[Cup of Joe]

Originally Posted By: boraticus
9000 watts! Something don't sound right there. Are these 120 volt appliances?

Anything drawing that much at start up should be changed over to 240 volts. That will cut your amperage by half. Much easier on the genset. I have a water pump at camp that is convertible from 120 to 240. I switched it from standard setting of 120 volts (50 amp surge draw) to 240 volts and now it's surge is around half of that.


That is what both my electricians said as well. Once we move from powering some of the smaller appliances on 120 right off the generator to putting 220 into the house it will actually be easier on the generator. Thats part of how I will be able to power the whole house with 7kw.

 

[turbodieselfreak]

Originally Posted By: boraticus
9000 watts! Something don't sound right there. Are these 120 volt appliances?

Anything drawing that much at start up should be changed over to 240 volts. That will cut your amperage by half. Much easier on the genset. I have a water pump at camp that is convertible from 120 to 240. I switched it from standard setting of 120 volts (50 amp surge draw) to 240 volts and now it's surge is around half of that.
The well pump and furnace blower (1/3 hp) are on 120 volts. I couldn't tell you what the pump wattage is without going into the well, but it's 120 only. The plate on the a/c (240v) as best I could read said either 4400 or 4800 watts. I used a general rule of multiplying by two to come up with surge wattage. I want to run the house during outages without rotating anything, as if grid power was never interrupted. If my needs still do not suggest a 12kw unit, by all means PLEASE suggest a diesel unit you think is more appropriate, before I buy something. Just to give ya an idea, I'm not the type of guy who wants a setup that will just barely scrape by-I like to build reserve into whatever my project is. Whatever genset I get, I'll get my money's worth as it will come with me if I ever move. Much obliged for the help.

 

[labman]

Ask Murphy. He will tell you some warm night the A/C, pump, and a few other things will all kick on at once allowing you to go reset the generator. Pumps aren't that big. I have a sticker in my box showing mine at 1200 watts.

Note, 9000 watts is 9000 watts to the generator, 120V or 240V. The 240 does give a balanced load.

When I was figuring my set up, my furnace, fridge, freezer, and pump added up to about 4000 watts if they ever all ran at once, leaving my 6250 watt unit plenty for the lights. I can easily run everything but the A/C and kitchen stove. Note, your 2X start up load is reasonable.

I have an interlock, http://www.interlockkit.com/intro2.htm
The cheapest, easiest, legal way to connect in a generator.

 

[boraticus]

Higher voltage will reduce surge loads. What ever the surge load is for 120 volt application will be reduced by nearly 50% if the same application is run at 220/240 volts.

Surge issues are more prominent than running loads. I've been using a diesel generator for 27 years. Once the surge is overcome, the generator will happily provide clean stable power.

The question is: Do you need 15KW to do 8KW worth of work. I'd calculate total load demand with and without surge and buy the minimum sized unit required to do the job. Remember running a larger engine to, generate more power burns more fuel. For instance, a fellow camper runs a 10KW unit powered by 1.6 litre Isuzu diesel engine. It burns more fuel at half load than my 7KW unit powered by a .855 litre diesel running near the same load. The difference in the amount of fuel is substantial. Both machines run at 1800 rpm. Mine will burn 1.5 litres/hr with a 5KW load, his is between 2. to 2.5 litre/hr. It seems that when the engine displacement increases, the fuel consumption seems to increase almost proportionately.

I'm not saying that this is definitive proof. There could be other reasons for his engine burning more fuel. My unit is almost twice as old as his and it's a Kubota.

Bottom line is that the larger you go, expect to burn proportionately more fuel.