Backup Generator size

[GarthH]

I've been considering a backup generator for emergency use. I would like to run our house with a minimun usuage like the fridge, a few lights, and electric heat in a few rooms (we have a separate electric heater in each room). Could anyone recommend an appropriate size in Kv's?

Thanks

Garth

 

[Shimon]

Since you have electric heat I would recommend an 8kw generator. It really depends on how many heaters and how many watts each heater is. How about hot water heater? Well water pumps? Electric stove? If you have any of those you may want something a little larger.

Will this be a portable or permanent or PTO gen?

 

[Cottonhawk]

Where you live can get to be very cold and it can be much much colder if your power is out! 8 kw should be enough if you keep low load, but I'd go higher so you have some flexibility.
We have just installed a propane powered 20 kw ONAN generator with automatic switch. It will power the entire house when the power is down and all I have to worry about is that I have enough propane in the tank.

 

[Mike_Lipke]

Electric baseboard heat is usually 250 watts/foot. That means every 4 feet needs a kilowatt.
If that is all you were going to run, then 8kw might be fine. But you have a refrigerator that prolly takes at least 1.5kw to start, .6 to run.

8kw will work, for the fridge and lights, but you will have to run the heaters one or two at a time, or when that fridge compressor tries to start, it can burn out. Big$$.

How putzy do you want to be when the power is out?
If you are on a well, that gets even more interesting.

 

[kennyd]

I installed a automatic 15kw Generac at my house 2 years ago...
But we need more info to help you.

There are lots of calculators online like THIS one that also can help you.

 

[randy41]

does that calculator assume you run all the power consuming things at the same time?

 

[salopez]

I believe that calculator adds everything up.

I went with a small 6.5 kw diesel for my condo. My switch allows me to run what I need when I need it...Ie I turn the fridge off to run the heat....

 

[kenmac]

My opinion,I wouldn't install any less than a 10 kw Might even go with 15 kw

 

[BobRip]

Heat is a very inefficient thing to run on a generator. Could you get a kerosene heat and a smaller generator. With a generator fuel becomes the limiting factor. At 1/2 to 1 gallon an hour (depending on load and generator size), you have to store a lot of fuel to run it even 12 hours a day. The kerosene heater is at least three times more efficient that a generator at making heat on a per gallon of fuel basis. A four kilowatt generator and a kerosene heater (or two) would get you by pretty well for less money and less fuel. If you are on a well, that is a whole different story. My well would not start reliably on anything less than an 8KW generator. This amount depends a lot on the depth of the well.

When it's cold outside, put you food in an ice chest that is outside and shutdown the refrigator.

Do you have a gas or oil furnace? They take much less power to run than even a small electric heater.

 

[gordon21]

Bare bones usage will require a 5500-6500 watt model for approx $600 plus extension cords.

Do NOT tie into the breaker box or backfeed through an outlet unless you know exactly how to isolate the system from the power company.

Alternating loads is the key to making a small unit acceptable. Run the water heater for only 2 hours and the water will stay hot for at least 12 more hours. Once you turn it off, then use those same watts to run the A/C or heat for a few hours.

You can usually keep a few lights, the refrigerator, a TV and the satelite dish running non-stop. They will need only 600-700 watts combined. The other 5000 watts are the ones you need for the big items.

If your budget is for $1200 or more, then you can get a lot more items running at once. A small whole house system with automatic starting will begin at $4000

$600 is the cheapest way that will provide any type of acceptable results.

 

[George2615]

I would agree with using a 10KW as a minimum for your backup power. If you don't have a welder, you might look into a combination welder / generator. I had to replace my 30 yr. old welder and upgrade my generator a few years ago so I got a Miller Bobcat 250NT 10KW welder / generator. List price was under $2800 when I bought mine. Actually, I got a factory reconditioned one with 19 hours on it and a 2 yr. warranty for about $2300 including 80' of new welding cable, electrode holder, ground clamp, and 10 # of rod. Miller, Hobart, and Lincoln all make similar units in the under 3K price range.

 

[RonMar]

Can you say energy management... An electric water heater will pull 4500 watts all by itself. A small electric stove burner is about 2KW, a microwave is about 1.3-1.5KW. Electric heat is also a real killer as far as load. It can be done with a small generator, but you have to manage your loads. This can be difficult with stuff that is designed to start automatically as if you don't control it, too much might attempt to run at the same time. If you have a well pump, depending on it's size, a 5-8KW gas generator from a box store might not be able to deal with the demands of starting the pump due to it's low inertia. These things can be overcome with the right generator and a good plan, but there are always compromises. How long are you planning on being able to power things. Gasoline generator consume an enormous ammount of fuel and gasoline dosn't store well long term. Also as evidenced in the northwest this last winter, the power outtages were wide spread and people were having difficulty getting fuel to run their gensets.

Just a few more things to think about.

Good luck.

 

[GarthH]

Sorry for the poor posting - yes we do have a well - quite shallow 12 feet water starts and I think the pump is at about 25 feet. The house is pretty large we would likely need to heat our solarium - it has about 15 feet of heater. The kitchen would need to be heated and likely one bedroom - rest of the house we would need to keep from freezing for water pipes. We do have a couple wood stoves - one in the solarium and the second in the basement.

I'm hearing about 15 to 20 KVs. We are getting natural gas installed on the property this year so I am hoping to have the backup gen set to be natural gas so I do not need to worry about fuel supply.

I am thinking of something permament - I might look into a portable unit for block heaters and the such.

I was hoping to find a used unit maybe at an industrial auction or something.

Thanks for all of the feedback

Garth

 

[kennyd]

I'm hearing about 15 to 20 KVs. We are getting natural gas installed on the property this year so I am hoping to have the backup gen set to be natural gas so I do not need to worry about fuel supply.

I am thinking of something permament - I might look into a portable unit for block heaters and the such.

I was hoping to find a used unit maybe at an industrial auction or something.

IMHO, The Generac system are a great value. Since you will have NG it's kind of no brainer to me to get a fully automatic system. But it's kind of like a insurance policy...you may spend the money and hardly ever us it! Mine has 55 hours on it two years, so it gets used!

I bought mine from Norwall Power Systems They had great prices and excellent service.

The problem with finding a used one is that they usually do not come with the transfer switches or control boards, or they are 3 phase units from factories or office buildings.

 

[RonMar]

Natural gas is probably the best deal for this type situation. Onan has some pretty nice small multi fuel fixed gensets. I just helped install 2 12KW units powered by propane at remote sites. Honda enines, good clean AC output waveform. If you shift some of your appliances over to gas as well such as stove, hot water heater and cloths dryer(electric cloths dryer uses 5KW), you could probably get by with a much smaller generator.

A good thing about the automated units is that they can be set up to automatically exercise on a regular basis. Probably the biggest killer of small portable emergency generators is lack of use. They only get run during an emergency. They suddenly get thrown into service and fail shortely therafter from internal corrosion from condensation or fuel system problems due to improper storage. What ever you get, run it untill warm every month or so to drive out the moisture and recoat the innards with lube oil.

 

[kenmac]

I'm hearing about 15 to 20 KVs. We are getting natural gas installed on the property this year so I am hoping to have the backup gen set to be natural gas so I do not need to worry about fuel supply.

I am thinking of something permament - I might look into a portable unit for block heaters and the such.

I was hoping to find a used unit maybe at an industrial auction or something.

Thanks for all of the feedback




The 20 kw generac 4 cyl. liquid cooled engine is a sweet smooth running engine. on nat. gas would be great !

 

[BobRip]

Sorry for the poor posting - yes we do have a well - quite shallow 12 feet water starts and I think the pump is at about 25 feet. The house is pretty large we would likely need to heat our solarium - it has about 15 feet of heater. The kitchen would need to be heated and likely one bedroom - rest of the house we would need to keep from freezing for water pipes. We do have a couple wood stoves - one in the solarium and the second in the basement.


Garth

I should take very little to start a well that shallow. Why go with such a big unit?

I think backing up with natual gas has a lot of advantage. Being way to paranoid, I just don't like to back up one utility with another. I think natual gas is so reliable that this is not much of a concern.

 

[kenmac]

B.T.W Forgot to mention , the 20 kw is direct drive The 15 kw is still (I think ) belt driven. I use to install a good many of these & at one time generac didn't recomend connecting a/c to a air cooled model . You can call generac to be sure this is still the case if you are thinking of running a/c with your unit.

 

[Cottonhawk]

Based on my broad based research I was impressed and bought a 20 kw ONAN unit. It is by far the best backup home generator on the market. It also is spendy. If cost is not a major issue, I suggest that you take a close look at the ONAN generators with automatic switching.

 

[Knotbored]

Local zoning laws require an automatic transfer switch if generator ties into house current, and one of those installed by an electrician costs as much as a cheap generator.
I can heat with woodstove, see via keroscene lamps, but wish I could find a way to wire my well up to a plug seperate from the house wiring. We have outages lasting several days sometimes, and bottled water isn't a great investment for flushing LOL.