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 Post subject: Generators - General Information before you buy
Post Posted: Feb 21, 2019 10:09 am 
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My husband sent information to a member here that was wanting to know what kind of whole house generator we had and I learned a lot so I wanted to share. Keep in mind, my husband is the guy that when you ask him what time it is, he'll tell you how to build a watch. One of the things I love about him. So go get some coffee, put your feet up and read on



Being both a mechanical and electrical engineer, and having used many generators to power my houses and business during power outages over many years, she thought you might find my observations and comments useful.

Let me begin by saying that I will be objective and note that there really isn't much difference in the quality, durability, or performance of generators that are designed for home use. All are compromise designs that use similar engines (basically large, air-cooled, lawn mower engines) that will last long enough for home use (not intended for extensive industrial use), and all will power your home during power outages very well.

So I don't think it much matters what brand you get as they are all similar. In fact, many different brands use the same engines. For example, Generac uses Kohler engines and Kohler makes both engines and generators. So it wouldn't matter if you bought a Kohler or Generac generator as both would have the same Kohler engines.

In your case, the engineering of the generator is not really your concern. You appear to have issues with the management and sales policies of the Generac company. So you should base your purchase on your satisfaction with the business policies and behavior of the companies that sell generators rather than the design of the generators themselves.

While the design and quality of home generators are similar regardless of manufacturer, there are several other technical factors that should guide your decision on what generator to buy. These fundamentally come down features and power vs. cost.

The first thing to do is figure out how much electrical power you require to run your home during an outage. This is an extensive topic that would require a phone call to discuss in detail if you wish. But in general, most homes will need a generator that can supply about 10 kW (10,000 watts) of power. If you are willing to seriously limit your power demands during an outage, you can get by with a 5 kW generator, which will save you quite a bit of money over a 10 kW or larger generator.

Keep in mind that we live at high altitude. The power of an engine decreases 3% for each 1,000 feet of elevation. So if you are living at 8,000 feet elevation, the power of the engine used in your generator will be about 24% less than it would be at sea level. This also means that the electrical output of the generator will be about 24% less than its rated capacity. This means that a 10 kW generator will only produce about 7.6 kW of power at 8,000 feet. If you live at 10,000 feet, the losses would be increased to 30%. Keep this fact in mind when selecting the size of the generator you need!

The next issue involves the type of fuel you want to use. Gasoline generators are a lot less expensive than propane ones. Both can provide the power you need, but if you get a gasoline generator, you will need to store a lot of gas for use during an outage. Remember that if the power grid is down, you can't get any gas from your local gas stations because there is no electricity available to run their gas pumps.

Fuel usage varies depending on how much electricity your generator will need to produce to meet your needs. But in general, an adequate gas generator will use about a half gallon of gasoline per hour during the day when you will be demanding a relatively large percentage of its electric power.

Fuel usage will be less during the night when you only need a little electricity to keep your heater running (assuming it is winter and your heater uses electricity to run its thermostat, propane valves, and pumps). So you may need to run your generator all night to keep your home heater operating. But the generator will use very little fuel at night.

You can see that you are likely to use at least ten gallons of gasoline per day (24 hours) if you use a gas generator. So plan to store about 30 gallons of gas at all times in case you have a power outage that lasts a couple of days -- which is not unusual up here in the mountains. I've had outages that lasted over a week where 30 gallons was not enough gas. But most likely, you could get more gas if you drove to Denver where they had power so the gas stations were open.

The nice thing about gasoline generators is that they are very inexpensive. You can get a cheap, portable, gas generator of 7.5 kW capacity using a single-cylinder, 13 HP engine for around $500. These even include electric start.

But portable gas generators are noisy, somewhat of a hassle to use, are hard to connect as a whole-home generator, and are not automated. This is in addition to the fact that they require you store a lot of gasoline makes them less desirable than a dedicated home generator.

So it is a lot more convenient and desirable to use what is called a "standby" (rather than "portable") generator. Standby generators do not have wheels, cannot be rolled around, so are not portable. They are built into noise-suppression, weather-resistant boxes that are installed outside your home where they are wired into your circuit breaker box so are ready to power your whole home at all times.

Most stationary generators can be run on propane or methane ("natural gas"), which you already have at your home in large quantities. So a propane-powered generator does not require you to store large amounts of gasoline. Also, you do not have to fill the tank of a hot generator with gasoline a couple of times per day since propane or methane will be piped into the generator from your propane tank or from your natural gas provider, so you will not need to fill the generator with fuel.

If using propane, you probably have a 500 gallon propane tank at your home, which will run a generator for many days. If you have natural gas, you will have a virtually infinite supply. So it is more convenient to use a propane or methane generator rather than a gasoline one.

Whatever type of generator you get, you will need to give serious consideration into how you will connect it to your home. Most portable generator users connect a couple of extension cords to their generators and plug their TV, microwave oven, lights, and whatever else they might want to use into the extension cords.

While this is a lot better than freezing in the dark, it is not practical to run a home's heater and well pump from extension cords. It is far better to wire a generator into your home's circuit breaker box using a mains switch so that you can use everything in the house in the normal manner.

The mains switch is essential as it disconnects your home from the grid and connects it to the generator. You cannot have your home connected to both at the same time as your generator would try to power the grid rather than just your home. Besides the fact that a home generator does not have the capacity to power the grid, it will also place a dangerous voltage on your local power lines that could electrocute a workman who is repairing the wires. So you must use a switch.

Most stationary generators have an automatic switch that will automatically disconnect your home from the grid, connect it to the generator, then automatically start the generator. This switch will also detect when the grid is back on line, switch your home back to the grid, and shut down your generator -- all automatically.

If you are using a portable generator, you will need to throw the switch yourself after you manually start the generator. While not difficult to do, it is a major hassle if the power outage occurs in the middle of the night, in a snow storm, in the middle of winter, with raging winds and sub zero temperatures. And of course, that is commonly when the power fails! So an automatic system is very nice indeed!

Stationary generators will have a built-in battery charger to keep the unit's starter battery charged at all times so the generator can be started automatically when the power goes out. If you use a portable generator that has electric start, you will need to supply a battery and battery maintainer/charger so that the battery is always charged and ready to use.

A battery does not hold a charge for more than a couple of months and you are unlikely to use a generator that frequently where it can recharge the battery. So you must supply a little battery charger/maintainer to keep the battery charged and ready to use. A stationary generator will do all this for you.

Due to the additional features and generally higher power of standby generators, they are much more expensive than portable generators. You can expect to pay several thousand dollars for a 10 - 15 kW standby propane generator, which is a lot more than what you would pay for a 7.5 kW portable gasoline generator. I am sure you are already aware of the prices, so I will not elaborate on this point.

So it all comes down to cost vs. features. If money is not an issue, then there is no question that a standby automatic generator using propane or methane is the best option. Expect to pay extra for installation and wiring it to your home unless you are really handy with tools and wiring and can install it yourself.

If money is a concern, then you can get by using a portable gasoline generator. It won't be as convenient or as easy to use, but it sure beats freezing in the dark when the power goes out. Since the power doesn't fail very often, the occasional inconvenience of having to set up and start a portable gasoline generator is not a major issue.

It is hard to justify thousands of dollars for the purchase and installation of a standby generator when you probably will only use it once or twice per year. Only you can decide what the inconvenience of a power outage is worth to you.

Personally, I have used many different generators over the years and have worked my way up from inadequately small, portable gas generators, through large gas generators, to my current 15 kW, propane, standby generator. But because I run my business out of my home, I cannot afford to be shut down due to a power outage. So a generator is essential and the cost of a standby generator is justified.

I might add that my current standby propane generator is the first generator I've used with which I was satisfied that it has sufficient performance. It is reasonably quiet, powerful, convenient, and runs the whole house and shop without limitations.

However, I did not want to spend many thousands of dollars on a standby generator. So I used eBay to find a used one. I got mine for only $2,000 rather than the $6,000 a new one would cost. So the price was reasonable.

Mine is made by Generac because that was what happened to be available on eBay at the time. It uses a 1,000 cc, twin cylinder, air-cooled, Kohler engine, which has proven to be very reliable and trouble-free. The generator head and electronics have been also been reliable.

That doesn't mean that I am totally pleased with the unit. It does not produce a smooth sine-wave output, its output is not regulated, and its generator head uses slip-rings -- which will eventually wear out -- instead of being self-exciting with no slip rings. So if money was no concern, I would buy a different brand that had better features.

However, the fact is that the Generac unit will probably last the rest of my life without failure while providing all the power I need during the increasingly rare power outages we have here in the mountains. For a price of $2,000, I'll not complain.

Although this information has been more of an outline rather than an in-depth engineering discussion, I hope you find it helpful. If you have further questions, please feel free to phone me at 303 838 8130 and I will be happy to provide whatever additional details you might require.

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 Post subject: Re: Generators - General Information before you buy
Post Posted: Feb 21, 2019 11:59 am 
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Wily Fox aka Angela wrote:
My husband sent information to a member here that was wanting to know what kind of whole house generator we had and I learned a lot so I wanted to share. Keep in mind, my husband is the guy that when you ask him what time it is, he'll tell you how to build a watch. One of the things I love about him. So go get some coffee, put your feet up and read on


Excellent clear concise post ... any chance your husband could run for President ?

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 Post subject: Re: Generators - General Information before you buy
Post Posted: Feb 21, 2019 12:31 pm 
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Thank you for this post! I'm considering a whole-house generator for our next house (wife and I both work from home) so this information is timely and appreciated! Saving it for later.


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 Post subject: Re: Generators - General Information before you buy
Post Posted: Feb 21, 2019 9:37 pm 
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thanks guys.

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 Post subject: Re: Generators - General Information before you buy
Post Posted: Feb 22, 2019 7:33 am 
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They also make interlock kits, mains return alarms, etc. for semi-permanent installation of portable generators:

https://smile.amazon.com/dp/B014BXH9QE/ ... _lig_dp_it

https://smile.amazon.com/dp/B003KREORA/ ... _lig_dp_it

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 Post subject: Re: Generators - General Information before you buy
Post Posted: Mar 25, 2019 12:12 pm 
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So now I have a question about the gasoline. How long do you guys store your gasoline before you worry about it going bad or getting gummy? What do you do with the gasoline, hopefully before it goes bad?


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 Post subject: Re: Generators - General Information before you buy
Post Posted: Mar 25, 2019 3:03 pm 
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I use a fuel preservative in gasoline for my generator, ATV and chain saws and have had no problem with one to two year old gasoline. I label containers and cycle them so that one does not sit too long. The brand stabilizer/preservative that I use is "STABIL" but there are probably other brands that may be just as good.


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