Generators

[id10t]

Figured I'd hit the collective wisdom of PPOT...

Hurricane season is coming again, and our power isn't so reliable anyway. So, I'd like to get a generator that would be capable of running what amounts to 2 circuits from my main electrical panel - the kitchen (for the fridge) and the living room (radio, lights, small window shaker AC unit, satellite, tv, cell phone charger). I've powered the AC unit and *everything* in the living room off a single 20 amp circuit with no overload, so I'm guessing I really need a generator that can power 2 20 amp circuits.

So how do I figure out how big of a generator I need? Also, what about fuel - is gas, deisel, or propane better? Should I look into having it hooked into the main house circuit, so when I need it I just turn off all the other fuses in the panel, disconnect from the electric co, and fire it up?

Help, id10ts wants to know

[widebody911]

There was a generator thread in OT just a few weeks ago; go fish!

[RickM]

Below is my contribution to one generator thread: Home Generators

Also, here's a link to a chart that will help determine appropriate size: http://www.harrisonhydragen.com/generatorsizing.htm



"I used to buy and sell these things...more as a hobby for pocket money than for a living. So here's a brain dump.....

Much of your choice will come down to budget.

While planning you have to consider what will be used while there is a power outage. Critical circuits only or what you'd typically use with utility power. Start-up load is very important. A well pump may only consume 4kw of power when running but may require 8kw to start. There goes the 5000kw (Surge, not continuous) rated Home Depot generator.

IMO the best choice is to go with NG if it's available. Diesel units can tap into a home heating oil tank for fuel...there a bit louder and smelly but live a very long time. Gasoline is messy, can go bad and may not be available and you have to transport in small quantities. Propane is expensive and requires tank refills.

Output from a NG unit will be less that the same running on propane or gasoline. However it's a bit quieter and you'll likely never have a shortage of the fuel.

You want the lowest RPM machine you can afford. For home back-up I would not buy above 1800RM. Lower RPM ranges are from 1100-1800. Other units are considered by many to be "Lawn Mower" engines. They're louder and comparitively short lived. These units are typically sold at Costco, Home Depot etc and run at 3600rpm. Do they work? Yes. Will they suit your needs? Maybe. Will it last as long as an Onan, Winco or higher end Generac? Not close. Hmmm, how is it that the discount store 15KW units are 20-30HP and the "commercial" level ones are 50-70HP?????

Transfer switches are what isolate power sources. Manual units look like big Frankenstein switches. Automatic switches are great but as you go up in Amperage the amount of the check you're writing gets much larger. Again a choice you make. Is it critical that power be continued if you aren't present? Do you mind throwing a switch, starting the generator and vice versa when the utility is restored? Traditionally 200-300 amp manual tranfer switches were in the thousands of $$$. My Square D lists for about $1800 (a good price). However, I've seen equally rated units at Harbor Freight for $200-$400.

Below is the 4 cylinder/65 HP Onan I have on a trailer.....sold to a gentleman in CA. Waiting to get picked up. I'll replace it with another similar Pre-owned unit (cost $1000-$3000). These things can handle a good sized house with many appliance running concurrently. Take the advice from others.....get an electrician to help plan and install.....further, an electrician that has experience in this field or else you'll end up being a guinee pig.

Edit: Remember if looking at used generators for a home you want 1 phase / 60 Hz."

[RickM]

Originally posted by id10t
Should I look into having it hooked into the main house circuit, so when I need it I just turn off all the other fuses in the panel, disconnect from the electric co, and fire it up?

Help, id10ts wants to know

Personally I'd have an electrician wire in a smaller automatic transfer switch to your panel. Especially if you're only doing two circuits. You may also want the switch to have the capability to "exercise" the generator on an ongoing basis. Just like a car it has to be run regularly.

Beware of any advice that suggests you "backfeed" the power. this is where one plugs the generator output feed into a socket to liven the house circuit. This is dangerous.

[Jims5543]

id10t - I originated the other thread. Where are you located?

What I am doing is arranging a local group buy with a generator supplier. We have decided on the Generac Guardian air cooled generators. LP or NG powered. The reason being is that we may need them for 10-15 days a year. Or, we may never need them for another 20 years.

I have 4 parties interested in the 15KW units. The price is $2975 so far but might be less. I have not negotiated the final price per unit yet.

I figure if we can arrange for 7-10 units we might get them to drop the price. Especially if it is all shipped to one location. From what I understand 3-4 people can carry one a short distance. Like from the bed of a pickup to the conc. pad it is to be resting on.

RickM - you were very helpful. I decided not to try to run my central A/C and just get a couple of decent window shakers. This way I can save litteraly thousands on something I potentially might never use. (I pray to god that statement is true)

For any of you that have never been through this. A hurricane. It is litterly hell on earth. It knocks you backwards 100 years when there is no electricity. There is no fuel, no grocery store, traffic lights are all out, lots of a-holes are out looking to steal your stuff. Police are spread thin and the bad guys know it. If you have a house like mine, back is all sliding glass doors opening up to pool screen enclosure. A task like opening the windows invites mosquitos, racoons (at night) and whatever else into your home. Especially when the screens are ripped.

I had considered moving to Tennessee, but love the ocean too much.

[Superman]

Originally posted by RickM
Beware of any advice that suggests you "backfeed" the power. this is where one plugs the generator output feed into a socket to liven the house circuit. This is dangerous.

Line electricians (Linemen) carry a 44 Magnum in their trucks for the purpose of killing generators that are backfeeding the power lines. Or maybe they don't, but they say they do. They hate those things. If you're going to use a generator during an outage, you will want to ensure those circuits are truly independent of the grid.

[dweymer]

Since I'm currently looking also, here is a site with some info www.nooutage.com; I believe current national code requires a physical lockout device on the transfer panel to prevent backfeeding through the panel.

[Robert Coats]

Caveat: I work for Honda Generators.

The preceding posts were all spot-on, especially about using a transfer switch to isolate a generator from the power company's lines to use your home's wiring/outlets. With "backfeeding," you run the risk of fire, or worse, electrocuting power company employees trying to get your real power restored.

Next, the comments about engine speed...most engine-driven generators are direct drive, so engine rpm = generator rpm. In order for such a generator to make 60 Hz power (the US standard) the engine/generator must run about 3,600 rpm. However, some new generators (still direct-drive) use an inverter circuit to make power, and can do so from idle to full-throttle, depending on the load. Inverter-type generators are more expensive, but run quieter (due to lower speeds) and use less fuel.

And about fuel. For home stand-by power, unless you're in an earthquake zone, natural gas is probably the best overall choice. Gasoline goes stale, and can be hard to find/purchase if the power is out everywhere. Propane ain't bad, as it won't rot, but it's about triple the cost of gasoline for the same amount of power. Still have to go fill up large, "tall boy" tanks or have it delivered, both of which may be difficult if the power loss is widespread.

For home stand-by power, I'd go with a permanent-installed, natural-gas unit and automatic transfer switch. Ironically, Honda doe not make either. So, I get by with a portable gasoline unit and some extension cords.

[Jims5543]

The generator I mention above for $2975 includes an automatic transfer swith. That will isolate the house from the incoming power line. It monitors the utility and if it senses restored power it switches back over and powers off.

It also monitors the incoming power, if there is an outage the generator comes on automatically and the switch, switches over to the generator in seconds.

[RickM]

Jim, I assume the ATS has the "exercise" feature as well...? If not you may want to negotiate for a unit that does. As mentioned it may be used once a week during the season or not for twenty years. Think about the car you depend on sitting for twenty years and then you go to start it.....yikes. Just reiterating that it's a nice feature to have.

Regarding engine speed. Most of the units I've dealt with were 1300-1700 rpm. However, they are also more on the commercial side. Still on the affordable side. The housings that come with the higher rpm models are better than in the past so noise is less an issue.

BTW, Catepillar makes home back-up units nowadays as well. Come to think of it an electrician friend is tight with the distributor. If you want to compare specs and prices for a group buy just PM me and I'll forward on.

PS: In colder climates don't forget to include the heater/furnace/boiler circuit....brrr. Ice storms are a common cause of outages.

[silver912e]

Just wanted to chime in that if you already have a gasoline generator, there are kits to convert them to natural gas or propane.

I got a Yamaha 5K watt geterator from US Carburetion, which came already set up for Tri-fuel (Gas, Propane, or Natural Gas). They also have conversion kits. Not affiliated with them, just had a positive experience purchasing from them.

[Robert Coats]

Originally posted by silver912e
Just wanted to chime in that if you already have a gasoline generator, there are kits to convert them to natural gas or propane.

FYI, every NG or LPG conversion kit I've ever seen just updates the fuel system alone. The problem with this is the higher combustion and exhaust heat produced by buring NG or LPG can tax the engine more, and reduce its service life. Specifically, the exhaust valve and head gasket are subject to premature failure due to the high heat levels.

Next, be aware a gasoline engine converted to run on NG or LPG will never make as much horsepower as it would with regular gasoline. Fact of life; expect 10-20% reduction in total power. Your 5Kw gasoline generator may only squeeze out 4250 watts with NG or LPG fuel. It gets worse with altitude.

Finally, for those nervous-Nellies, converting a gasoline engine to run on a different fuel violates federal EPA and California CARB regulations. And spitting on the sidewalk is illegal too.