Hints for choosing generator for new home Gen Interlock setup

[Jack]

Had a major electrical re-do of my house, and had the electrician install a generator connection. I believe they are called "generator interlock" systems. It is a standard setup, I can throw a switch in the basement, then plug a generator in outside the house to power the house in event of a power failure.

(save safety warnings.. I know to put generator outside not near door or window, and I can't hook Gen up while still connected to municipal power supply due to lockout system on inside panel, and I know enough to not overload gen)

What should I look for in considering a generator. I am pretty much settled on Honda, as in my experience they are just head an shoulders above all others in reliability and noise. I am prepared to entertain opposing points of view, but I am willing to pay a little more for a good unit.

I don't need super-megawatts.. I will be happy to see that my home has heater, hot water heater (powered venilation unit) and a few lights and maybe a TV. I don't need to run the AC or electric stove.

Could I get away with one of those tiny suitcase type units.. my concern is that they seem to only have standard AC plugs on them, not that special generator circular locking plug that goes into the outside outlet.

Personal experiences or tips? Good online sources for info?

[Pete C.]

Honda is about the best for noise in the small portable generator category, Yamaha has some units that are pretty comparable. In larger units there are others that are very quiet as well. As for reliability, there are other brands that are very reliable as well.

Heat and HW are gas or oil? Got a well pump that needs power? 5 KW or so will do pretty well for an average house without unusual loads. Refrigerator, lights, TV, a burner on the stove for coffee and furnace and well pump do pretty well with 5 KW. If you do some load management like insuring the furnace and well pump aren't on at the same time you can get by with less.

The real small units are 120V only, a normal transfer switch / interlock really needs a 240V feed. A small unit like a Honda EU2000i would handle a refrigerator and a light plugged into it, but is unlikely to handle a furnace or other larger loads.

Again, the more load management you are willing to do the smaller a generator you can get away with. Nearly all of the typical large household loads are ones that do not require full time power. The refrigerator can readily go an hour without power while the furnace runs for example. The well pump can go without power while you microwave dinner.

Ran a ~1,500 sq ft house with oil heat / HW, well pump, electric stove, microwave, lights, TV, etc. for three days on a Generac 5 KW gas portable generator. Baked stuff in the oven too. Other than the noise and periodic refueling (which I did very carefully while running) it was just fine. Changed the oil after that run.

Perhaps alt.energy.homepower though that leans more towards conservation and renewables. Still most folks off grid with renewable systems have a regular gas generator as backup since renewables aren't 100% reliable, so some expertise there.

Pete C.

[Toller]

I have a Honda EU2000. It powers my furnace, fridge, freezer, and TV. Not only is it nearly silent, but it gets great mileage. If you have ever tried to buy gas in a major power outage, you will understand that the smallest possible generator is the best generator.

Get an ampmeter and see how much current you need to start/run all the components you want to run. It can vary greatly; my old furnace needed 12a to start, the new one is 2a. Then you have to decide how much you need to run simultaneously; can you live with your furnace and water heater each on half the time? My guess is that the EU3000 will be the best fit, but you have to check things out first.

[Chris Friesen]

What about the refrigerator?

This page has some information on generator sizing:

Chris

[Toller]

I could have sworn it ran my furnace for 5 days two years ago, as well as my refrigerator and freezer.

[Pete C.]

It may have depending on what you have for a furnace. In many cases it won't.

Pete C.

[Pete C.]

No, the smallest generator that will handle your load with some safety margin is the best generator. You need to maintain a fuel supply to cover the longest reasonably expected outage.

For the folks in the northeast who heat with oil, a diesel generator is the best since their 275 gal + oil tank will provide weeks of fuel.

You can also store a decent reserve of gasoline if you have a safe place to keep it. Store it in 5 gal cans with Stabil added and rotate them out into your car annually and refill.

A clamp on amp meter with a peak hold function is very useful if you don't mind digging in the breaker panel to use it. For the breaker panel adverse a little meter like the Kill-A-Watt is very useful.

Pete C.

[HeyBub]

If you have natural gas service, get a gas-powered generator. You NEVER lose gas during (most) emergencies [maybe during an earthquake?]. With gas, you won't run out of fuel and the fuel won't go all gamey on you.

Water heater? What for? Heat some water on the stove for a sponge bath if things get rank. Electric water heaters really suck (the power).

The circular plugs are for 240 connection (or two 120s). If you're clever and cautious, you can rig an adaptor.

Better, for a few lights and a TV, would be... wait for it now, don't get ahead of me ... AN EXTENSION CORD.

Connect this EXTENSION CORD to an inverter plugged into your car's cigarette lighter. 2-300 watts ought to do it.

[Doug Miller]

And in many cases it will -- really, the only cases in which it won't are electric furnaces or heat pumps. The electrical demands of oil- or gas-fired forced-air furnaces are quite modest, and those of hot-water systems are even lower. A typical refrigerator requires much more power than a typical gas furnace.

[nicksanspam]

Seems unlikely, unless the fridge contains a 400 watt blower :-)

Nick

[Pete C.]

Remember, the EU2000i is rated 1,600VA continuous and 2,000VA for 30 min max. In order to handle many of those furnaces you'd need to do load management so the furnace was the only load at the time.

Pete C.

[Pete C.]

An earthquake or a flood are both likely to take out your NG service. You may be on a hill out of the flood, but if your feed runs through an area that's under water there is a good chance it will be turned off. There are other causes of NG outages, but they usually don't align with electrical outages.

As for fuel getting "gamey", that is simply not a concern if you are capable of a small amount of maintenance.

Gasoline will readily store just fine for over a year with an additive like Stabil. Store in 5 gal cans and rotate them out into your car annually and refill and they'll be just fine.

Diesel will keep even longer if you use diesel Stabil and you can rotate into your diesel car or truck the same way. If you heat with oil, you already have a 275 gal + on site fuel supply that a diesel generator will be 100% happy with and you'll have no fuel rotation issues at all. Remember that "home heating oil" is also called "off road diesel" and is what most construction equipment is run on since it's cheaper due to the lack of transportation fuel taxes.

If you heat with propane and have a big "hot dog" tank, and LP generator will do nicely and again no fuel rotation or outage issues.

NG is really the only fuel you can't readily store in a useable quantity. If you have NG service and get gasseous fueled generator, you can get a big "hot dog" type LP tank as backup since the generator can readily run on either fuel.

Pete C.

[Toller]

Lets see, my old refrigerator required 23a to start and 3a to run; my furnace is 2a. Seems higher to me, and neither are unusual. (my new fridge is 13/1.5)

[Doug Miller]

Checked a rating plate on a refrigerator lately? I'll bet not.

The one in my kitchen is marked 6.5A. That's a bit more than 400W.

[Toller]

And what exactly what is a safety margin?

The longest outage we have had around here recently is 12 days. You can't store a 12 day supply of gas, even for the Honda EU2000. Diesel? Natural gas? Please!

I keep three 2 gallon cans of gas, and rotate them through my lawnmower/snowblower. That is enough to keep me up for 2 or 3 days. It might not be easy, but there is always someplace to buy gas in 3 days.

[Doug Miller]

Nonsense. 1600VA = 13.3A at 120V. Where have you seen a gas furnace with a blower that pulls thirteen amps? Half that is a little more like it.

[Pete C.]

BS.

Here now I currently have what would be a 12 day supply of gas for an EU2000i, about 30 gallons. I cycle through the cans pretty frequently with the riding mower, towable leaf vac, line trimmer, chain saw and whatnot, very easy to store. Here I have an EU2000i and a 5 KW Generac.

At my other facility which has oil heat, there is a 275 gallon oil tank and a 25 KW diesel generator. The generator consumes around .75 gallons per hour under typical loading so there is about 12 days there as well when you account for the furnace fuel needs as well.

I keep six 5 gal cans of gas and a 1 gal can of 2 cycle mix. I use Stabil and have never had an issue with any going bad. It gets rotated with plenty of frequency.

Pete C.

[nicksanspam]

Yup. Good ones use less than 1 kWh/day.

Nick

[Doug Miller]

Go check the rating plate on your refrigerator. See how many amps it draws. Now go check the rating plate on your furnace blower and compare.

[Pete C.]

That's not a nameplate rating and it's utterly meaningless. The refrigerator could draw 1 KW if it had a total run time of an hour a day.

The defrost cycle on a refrigerator doesn't last long, but it draws a substantial amount of power for the heating element.

Pete C.