Home Generators - Kohler?

[W1UJR]

Looking at buying a home generator for the QTH, have been checking out the Kohler series.
Want something to auto-switch if I am not there, run the house and radio shack/barn.

I was quoted on Kohler 14RES.

Opinons on Kohler units, pro/con?

Was quoted on a 14KW unit, wondering I am better with a 20KW?

Any other fine points to consider, ask or ponder on?

Thanks - Bruce

[N4LTA]

I design quite a few large generator systems, and every now and then a small residential system.

Kohler is a good generator and they make a good residential option. I have always considered them slightly behind Cat and Cummings but not far. They are way ahead of the Generac and similar generators.

You are looking at a very good system - not a Home Depot special - and going up to 20 KW won't cost that much more.

Have you had someone run a computer study of your load and especially a study of how much HVAC compressor starting load that you have? Starting a HVAC compressor takes a lot of KW and usually when you have this covered - you have a good bit of resistive type load capacity left over.

I find that many electrical contractors just add up the load and select a genset and get into real trouble. A motor laod takes about 600% of running load to start and if the genset can't deliver - you have a problem. If you have two compressors you can step start one - then another and save some capacity. This is easy to do with a time delay on one compressor unit.

Pat
N4LTA

[W3SLK]

Pat said:

I design quite a few large generator systems, and every now and then a small residential system.

Pat, I'm curious as to your preference: propane or fuel oil?

[KM8AM]

We lose power an average of one a week.  We installed a Kohler 12RESNT w/propane.

We have two 1000gal tanks.

Except for the range, and the geothermal system, we have b/u per to all circuits.

We can heat with wood.

Even the LUSO crank up tower is backed up.

We have carb and battery heaters and the auto exercise board installed.

Love the autostart.

[W1UJR]

Thanks guy, exactly the feedback I was looking for!

Pat, don't think I could picked a better person to ask, wow, was that taylor made or what?
To answer your question on A/C, no A/C in the house, not common in Maine, and my place was built in 1860 anyway, not well suited for A/C. We are moe concerned about staying warm!

What I do have is a midsize boiler for radiant heat, and other normal loads like a fridge, washer, gas dryer, water and sump pumps,netc. The rep suggested a 14 KW unit, but agreed a 20 KW might be better if we plan an addition, cost difference is a little less than $1K. Claims larger units use less fuel than a smaller unit working near max load?

The contractor is telling me that it is better to put the unit on a pressure treated 4 x 4 wood on top of crushed stone, rather than a concrete pad. Claims that concrete will move with the ground freeze/thaw. Your thoughts?

We do have propane, hope you think Kohler is still ok! Mike wondered about your preference on thus as well. We've got a large underground propane tank which powers the cookstove and boiler.

Again, appreciate the help fellows!

- Bruce

W1UJR - A Tad Off The Beaten Path

[WA3VJB]

Diesel: downside is cold weather/ fuel gelling up
Gasoline: downside is fuel gets stale
Propane: downside is delivery by supplier


I understand the hot ticket is to get propane with adjustable jets and fuel switchover with connections for external LP Gas canisters like for outside BBQ grills.  Lets you bridge if the delivery truck can't get there for a while, like in our snows here last winter.

[Opcom]

I had a Kohler 3.5KW 1800RPM gasoline unit and was happy with it. I sold it only because I bought a Mankato 40KW diesel machine to run the whole house. It is 2X overkill but it was cheap. Oversize is important for both voltage regulation and frequency regulation if you have A/C. Even on the 40K, you can tell when the compressor starts. But it seems you don't have such difficult loads so you ought to do well. In Texas, never seen diesel gel yet.

The real choice was between diesel and natural gas. Natural gas has yet to ever be interrupted and it is cheaper than diesel. I've been told a diesel set can run on (switch over to) natural gas, and also been told it cannot.

[W3SLK]

I don't have to worry about fuel oil gelling either. I was thinking more along the lines of the fuel for the furnace and using it, (the only difference between is diesel you pay fuel tax). We have both at work and they do equally well. I have fuel oil for the furnace and propane for both the fireplace and the stove. We can get by with fans in the summer so the A/C isn't an issue. Its the water pump, furnace, fridge necessities that are important. We lose power here often and for lengths of time. The heat is the real important thing in the winter.

[Mike/W8BAC]

Is it legal to use fuel oil in a generator? If I recall correctly home heating "oil" is highly refined diesel or sometimes called karosene. If the use of heating oil is legal and heating oil is available at a reasonable price in your area it might be worth considering.

When you look at gas powered generators it seems that power output for a given size engine is highest with automotive gasoline, Natural gas is less and propane is at the bottom. The advantages of natural gas and propane is a very clean burn.

The best bang for the fuel buck is diesel. It seems to me most diesel gen sets run at a much lower rpm because of the lower rpm torque. Heating oil is very well stabilized for low temperatures so jelling doesn't occur. I would think a diesel gen set for fixed home or farm use would have a block heater available (as should a gas set) to make cold starts easier. My choice would be a diesel set IF heating oil could be used.

I have to admit, I really like diesel power. I have been driving diesel powered vehicles for 20 years now. I wouldn't hesitate to use a modern diesel generator. Newer high tech diesel engines are very clean burning. Add the use of the very low sulfur heating oil (if it's usable) and it's a no brainer.  Your home may even have a left over tank.

My 2 cents worth.
Mike

[N4LTA]

The best fuel by far is diesel. The diesel has much more starting torque and step function torque than an ignition engine. But with that said  - cold weather is a problem with diesel.

Natural gas and propane work well and gasoline also but athere are some safety and electrical code issues with gasoline tanks and storage. If natural gas is not available - propane would be my choice.

The NFPA allows for propane and diesel fuel for emergency systems but natural gas only with permission from the athority having jurisdiction because it can be interrupted in an emergency.

You have an ideal situation in that all of your load is close to being resistive and so you can use a small genset and not worry about motor starting. If you had a couple of 3 ton AC units you would probably need a 30 KW unit.

We put them on a concrete pad here in SC, but I'd go with your local contractors advice as we don't get the ground freezing here any deeper than an inch or so and for no more than a week.

I just designed a system for a large house using a diesel system. He needed a 40 KW system and it was very expensive. We priced a Cummings diesel system. At that load, three phase would be preferable but he has a single phase system.
He had been looking at the Home Depot Generac systems and was very surprised at the cost.

[W1UJR]

Thanks Pat!

You mentioned Generac systems, I noticed the sales rep had both Generac and Kohler stickers on the side of his truck. I asked him why he quoted on Kohler rather than Generac and he said that he sells Kohler as he does not like getting called out when the generators don't start, sounded like an honest answer. We are down at the end of a peninsula, the first to lose power and the last to get it restored!

Really appreciate the input, judging from the wuedtions and replies, looks like this was a good topic to bring up, esp here in the Northeast!

Happy Thanksgiving everyone!

[W3SLK]

Diesel, fuel oil, heating oil are pretty much the same thing. Here in PA heating oil is advertise with "Red Treatment for clean burn." In actuality, the red dye is to prevent a person from using it over the road since there isn't any road taxes on it. A DOT officer can place a device in a fuel tank and determine if with in the last month you ran heating oil and levy a steep fine on you. I've ran both in my tractor. Back to the point. We have both propane and diesel at work. The propane ones are  used on the smaller units even on the V-6 driven jobs. The one diesel that I know of is a 1M jobber used to run our Joy compressors to supply 30 psi air pressure for all our fementors.

[KG6UTS]

Kohler gen sets have been dependable for us in some pretty remote places and friends have them in RVs and boats with equally good results. A neighbor in Borrego Springs has a, I think, 40KVA running on propane. Lots of power problems iut there due to lightning strikes during summer storms. I can't remember the % of load needed to keep regulation happy.

EdZ

[W2PFY]

You'll never have a problem with fuel oil as long as it's a 50/50 mix of kerosene. I lived at my camp for two years running my generator all night at times just to stay warm when it was 30 degrees below zero. Do not put a fuel filter at the output of the tank, put it in near the generator out of the direct atmosphere. If you put the filter at the bottom of the tank it will jell even with 50/50 mix. Just my experience, yours may differ.  

My first year staying at the camp was was a lesson in survival. It never went above zero for two months. Good ice fishing though

One of the things Kohler brags about is their pure sine wave. I think they use what is called a 2/3 pitch winding that greatly reduces harmonics. Make sure it's a brush-less design with electronic regulation.    

[N4LTA]

The problems in the south are thunderstorms and ice storms. Lots of commercial and small industrial facilities are installing generators.

I am doing a project now with five 1.6MW/2.0 MVA 12.47 KV Cat diesels running in parallel for power generation to the grid. The  fuel source is very unusual. I can't talk much about it at this time.

[W2PFY]

The  fuel source is very unusual. I can't talk much about it at this time.

Cotton?

[N4LTA]

Ask me in a few weeks. I can talk more about it then, but it's not cotton. It is a waste stream of mixed content. The conversion process is the secret.  If it works as it is suposed to - I wish I was a stockholder.

[The Slab Bacon]

FWIW, the ONLY difference between #2 diesel fuel and #2 fuel oil is the dye and the road use tax! the dye is so the "proper authorities" can tell if you are running heating oil in a vehicle and not paying the road use tax. Also it is perfectly legal (at least in this state) to run #2 fuel oil (or heating oil if you must call it that) in bulldozers, pumps, welders, generators, earth moving equipment, etc because they are NOT being driven on the highway.

IMHO, the best choice for a fuel type should be what you have on hand. (whatever you heat with) Propane, natural gas or diesel, this way it is always on hand and you dont have to think about keeping your tank full. It is always there.

Gasoline is a poor choice for a STANDBY generator as it goes stale with time and usually causes fuel system damage in the process. (varnish) And you have to change your fuel every year as well as your engine oil.

Diesel fuel goes stale with time but still runs fine in the engine, it just changes color and smells peculiar.  I have a small tractor that is diesel that I dug out of mothballs this year after not being run for about 20 years. The fuel smells funky, more like Varnaleen than diesel fuel. It even has some of that black algae that grows in fuel oil in it. A fresh battery and about 10 revolutions of the engine and it came right to life and runs fine with the old fuel in it.

Patrick, I dont know if they are available in smaller sized units or not, yet. But for years they have used very large engines that run on both diesel and natural gas for natural gas line pumping engines. They use both the gas and diesel at the same time. They are compression-igintion (diesel) type engines that use a very small amount of fuel oil injected into the combustion chamber to light it off and a carburetor to meter in the natural gas to run the load. These are very large multi cylinder engines, large even in comparison to locomotive diesels. I have a friend that has a very specialized machine shop to rebuild them. This design has been around for decades.

[K6IC]

My 2c ...

I do have one Kohler -- an 18 KW unit from about 12 years ago.  It is fine,  as it is an 1800 RPM LP-fueled job that is powered by a Ford in-line four and is water cooled.

The current generation of residential backup gensets are quite a lot less expensive than the old units like mine.  And, depending on the nature of your power failures,  the RES-14 will probably be fine.  These units run air-cooled engines,  and run at 3600 RPM.  They might not handle long-term power outages too well.

My application for generators is for battery charging in an off-grid hammie QTH.  This application is hard on gensets,  where Diesel units are preferred,  as the run-times can 5 or so hours at a fairly constant, heavy load.  My favorite genset is a Kubota 25 KVA Diesel which is very quiet,  and is switchable twix three-phase and split-phase (120/240 VAC).

But if your power outages are minutes to an hour or two,  a few times per year,  and you do not have constant,  heavy loads the RES units may well work fine,  and the price seems good.

YMMV and so on.  73  GL  Vic

[k4kyv]

Is it legal to use fuel oil in a generator?

If you paid for it, it's yours to use in anything you want, except to run vehicles on the highway, which requires fuels that were purchased subject to road tax. Farm tractors are exempt from the road tax for "occasional" use on highways, such as driving the tractor to a nearby work site.

A few years ago they started charging fuel tax for undyed kerosene used for heating (that doesn't gum up heaters), but you could request a refund on your IRS form.  Truckers were allegedly using kerosene and heating fuel instead of taxed diesel fuel on the highway, but that doesn't really make sense.  Kerosene (minus road tax) is still about $1.00/gallon more expensive than diesel fuel with tax included.

[w1vtp]

Is it legal to use fuel oil in a generator?

If you paid for it, it's yours to use in anything you want, except to run vehicles on the highway, which requires fuels that were purchased subject to road tax. Farm tractors are exempt from the road tax for "occasional" use on highways, such as driving the tractor to a nearby work site.

<snip>

I think it's in VT that they actually sell "off road" #2.  I believe it's without the tax.

[Mike/W8BAC]

Don't farmers have to document what that fuel is used for or apply for a use permit?

I stopped at a rural station in Wisconsin once and found two diesel pumps with different prices SO naturally I started pumping the cheaper of the two. A few moments later the pump stopped... I went inside and the lady asked for my off road permit. Than she told me how much trouble I was in. She was kinda rude so I was looking over my shoulder as I left the county.

Mike

[W3SLK]

Yep, off-road is for use in anything that 'technically' isn't licensed for being on the road or in PA's case, has "FARM" tags. Kerosene is the samething being dipensed for the sole purpose of use as a heating fuel.
Slab Bacon pretty much answered my one question but left me standing with another. I have both propane and fuel oil here. If I were to go to propane, I would have to get a larger tank and pay the elevated 9/11 HAZMAT fee that goes with it. I could use fuel oil but I would have to probably install a secondary fuel pump to push the fuel from the basement up to grade where the gen-set would be sitting. 

[Mike/W8BAC]

I think a lift pump for the fuel oil would be a good idea Mike to make sure the supply was at the injection pump at the moment needed. A typical mechanical injection pump on the engine would probably do fine without a charge pump but the line might loose prime when not in use. A charge pump would help assure a quick start. Having the oil indoors at a warmer temperature might help it burn better during cold weather use. Sounds like a great start.

What is an "elevated 9/11 HAZMAT fee" all about?

[Bill, KD0HG]

Diesel is way more fuel-efficient than propane. Maybe makes twice as many KWH per gallon. With a 5 KW load, you'll use about 1/2 gallon of diesel per hour, at 10 KW around 1 gallon per hour.

Compare that to propane: A 10 KW generator with a 20 HP engine would consume about 200,000 BTU/hour. Propane contains about 90,000 BTU/gallon. That's at an assumed 100% engine efficiency, diesels are far more fuel efficient than gasoline or propane spark-ignition engines.

Commercial diesel back up generators have thermostatically controlled fuel heaters and some constantly circulate the tank's fuel through filters with a small pump. This can also be a lift pump.

In an emergency, you can run diesels on any vegetable oil from the supermarket- Canola, soy, Mazola corn oil, even warm (liquid) bacon grease. Kerosene is also a useful fuel in diesels. And you can use #2 heating oil or motor fuel. Rudolph Diesel made his first engines that ran on peanut oil, there wasn't a refined petroleum industry back then.

Downside is that #2 diesel fuel can have a limited storage life. It can support algae growth if even a small amount of water is present. You need to add a diesel biocide to the tank if it is stored for years.

The gasohol being sold in many states is nasty to carburetors. I have found it corrodes needle and float valves- eventually- if they're not drained before long-term storage. (Yes, I now know how to rebuild Briggs and Stratton carburetors- LOL). A gasoline additive is "Sta-Bil" which is supposed to preserve gasoline and prevent gumming. I use it in my own 7.5 KW standby Kohler.

Another option I've looked at is running an AC generator off the PTO of my diesel farm tractor. Not automatic, but cheaper than having to buy another engine along with the genset. The generator gets bolted to a pad, you back the tractor and PTO shaft up to the generator.

How about a wood-fired steam engine?