Generator Question

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  #1  
Old 10-31-12, 12:49 PM
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Generator Question

I recently purchased a portable generator that I eventually will have an electrician tie into my house by transfer switch. My question relates to how much I can run on it. Purchased this generator during emergency northeast weather a couple days ago so I did not have any options on sizes as this was absolutely the only one I could get quickly.

Briggs and Stratton Storm Responder 5500 Watt Running, 8250 Watt Surge.

Question - Total Watts of items I want to tie into generator is 5200. The item with highest usage by far is 2250 watts running and 4500 watts surge (AC Central Air). Can I run all of these items at the same time on the 5500 watt generator since the total is 5200 or is that cutting it too close? Does the large surge from the large item come into play here?

Thanks for any help.
 
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  #2  
Old 10-31-12, 01:06 PM
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I can see the generator stalling when the a/c compressor tries to kick on. Why don't you just use a small window unit if you absolutely need air conditioning? Also, that generator only has a 2-pole 20A breaker.
 
  #3  
Old 10-31-12, 09:20 PM
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Is your central A/C also a heat pump? I'm not sure if central A/C is A/C only which is why I ask. If a heat pump you need to factor in the AUX heat or electric heat which draws a ton of juice if it kicks on.

Also with a generator you need to balance the load somewhat. By this I mean there are two 120V legs and your generator is rated to provide half it's wattage for each leg.

Your A/C draws 2250 so that's 1125 per leg. If you have a circuit running that is pulling a thousand watts or so already then you only have 1500 watts left for that leg. The A/C draws 2250 on two legs for 240V...1250 each. Factor in a surge to start the compressor then you run into problems.

Generators can run with a slightly off balanced load but not something you want to take too far. Having a wattmeter box installed when the transfer panel is installed is a very wise choice so you can monitor the load on each leg.

I think the generator can run your central air, but when it's running you don't have much room to run much else at the same time.
 
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Old 11-01-12, 07:06 AM
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There is no way that generator will power your central air. And why would you want to anyway? Virtually all power outages occur in the winter. And if your central air is really a heat pump, there's even less than no way. My heat pump is on a 45 amp double-pole breaker.

My local Home Depot had an entire aisle filled with those Storm Responder units. I suspect lots of people now own a generator they'll never use again, if they used it at all. I live in the Eastern Panhandle of WV (Harpers Ferry area) - we didn't lose power or even satellite tv during Sandy.
 
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Old 11-01-12, 08:02 AM
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My AC is not a heat pump. If I can't do it, it's not a big deal at all, I just wanted to know my capabilities. And yes, I'm sure I will be using my generator a few times a year since I lose power multiple times throughout the year, I assume from living in a heavily wooded area, and not always in the winter. And with it being portable, it has many uses, not just when my home power goes out.

Thanks i6pwr for posting meaningful information.
 

Last edited by ray2047; 11-01-12 at 08:23 AM. Reason: Remove inappropriate comments.
  #6  
Old 11-01-12, 08:41 AM
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Generally speaking, you aren't going to be able to run central AC off a generator without getting something huge. Normal process is to run a window unit in the important areas of the house if you have to have AC when the power is out.
 
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Old 11-01-12, 06:49 PM
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Virtually all power outages occur in the winter.
You have been very lucky! Tornados generally occur in the spring through early summer, but can happen any time of the year. They generally cause a lot of power outages when they occur.
 
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Old 11-01-12, 06:59 PM
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Down here 99% of power outages are summer from thunderstorm activity.
 
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Old 11-02-12, 07:38 AM
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"You have been very lucky! Tornados generally occur in the spring through early summer, but can happen any time of the year. They generally cause a lot of power outages when they occur."

Luck has little to do with it. I'm quite familiar with tornadoes (used to live in Kansas). We don't have them where I live now. And the few outages we've had from a summer thunderstorm have been for only a few minutes.
 
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Old 11-02-12, 08:21 AM
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Originally Posted by nrowles
And yes, I'm sure I will be using my generator a few times a year since I lose power multiple times throughout the year, I assume from living in a heavily wooded area, and not always in the winter. And with it being portable, it has many uses, not just when my home power goes out.
Myself and my parents are in a similar situation. My parents live on a lake in the bush, and myself, in a small cottage town.
One thing to consider when you look at getting your generator tied in to the house through a transfer switch of some sort, is your power requirements will change season to season. A transfer box with dedicated breakers probably will not be the solution for you as items you need in the summer, are not always items you need in the winter.
My house as an example in the winter, my boiler is a must. During the summer, my sump pump would be a priority (odds are I'm loosing power during a rain storm).

The transfer switch arrangement I'm going with is similar to what my dad has installed. It goes inline before my pannel and allows me to select from my main pannel which breakers I want to feed. On my main pannel, I'll mark which items stay on for summer and which stay on for winter use before throwing the transfer switch over to the generator.
My dad's setup (which was a custom build) has a light on the grid side, which when the grid goes live, the light comes on letting him know he can kill the generator and go back to the grid. I haven't seen a commercially available kit that has this light setup, but I'm sure it's out there.
 
  #11  
Old 11-02-12, 09:18 PM
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Nrowles, the fact is you have already purchased a generator, I purchased one that's about the same as yours wattage-wise but was 5000/6250.

Before you get all the parts to hook it up, now is the time to reassess your situation. Yeah it's a PITA to return or sell what you have if it will not fit the bill in term of watts, but in the end it will be cheaper and you will be much happier knowing you can run everything you initially intended.

That being said, my 5 KW would not start my A/C compressor, keep in mind you need your air handler to run at the same time. Doesn't take much to run the fan, but alot to start it up since they tend to start at almost the same time....A/C compressor and air handler.

Since you have A/C only, do you have electric heat strips for emergency heat?

md2lgyk: Your 45-amp breakers are probably for your additional electric heat.

What I did was change out my main panel to a generator-ready panel, (50A service) this way I could use any circuit in the panel. I installed a 30-Amp inlet, 30-Amp wattmeter box and the necessary size wire for the inlet box to the breaker in the main panel since at the time my gen was rated at 20A (5KW) and I figured I would up the gen size to 30A in the future, maybe a 50A if the price was right.

Turns out I needed a larger generator so I had to change the inlet box, wattmeter box, and the wires to a larger gauge, just be sure you size your equip right from the start. I ended up with a 11KW continuous (50A) only because I got very lucky on a CL find..and the panel was not needed to be changed . This is what I needed to start my well pump unfortunately..

Knowing I can energize any of the circuits is very nice, no need to decide which circuits to leave out. I went with a new panel beause my POCO would not allow the Generlink, they recommend a manual lockout rather than automatic.

Generlink

This is nice because you don't have to change anything, can be installed in less than an hour by the POCO, pricey but it's your's to keep if you move.

I would recommend purchasing your equipment to handle 50-Amps, this way you can use a 30A cord for hookup and just use a larger 50A female end for the transfer switch with your 30A generator.....you just don't want to work it the other way around.....50A gen to a 30A hookup naturally.

This will allow you to upsize later keeping your existing transfer switch, worst case only changing the generator cord instead of all the other equipment.

Reason I'm rambling on is I had a 5 KW unit, once I had it I wanted to find a way to make what I could work and quickly realized how much current is required to start an electric motor, something we don't thnk about when they are hooked up to the grid.

Microwaves, hard to run without clean power.

Refridgerator compressors take a decent surge.

When the power is out for days you tend to get desperate and need to factor that in. I have discovered that 5 KW units are great for short use and running extension cords.

8KW units work well since a few of them surge at 10-12KW and can start alot of motors.

10KW and up are ideal for hooking up to the house since electric motor demand isn't that much of an issue.


Granted the smaller ones will work but they don't run as much as you may think.

Hope all this helps.
 
  #12  
Old 11-03-12, 01:16 PM
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I don't have "additional electric heat." It's a hybrid system - the backup to the heat pump is a gas furnace. I suspect the 45-amp breakers are because it's a 3.5-ton unit.
 
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Old 11-03-12, 02:30 PM
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