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Old 08-13-2012, 06:47 PM   #1
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running AC unit off generator


i live in a area of arizona there temps get to 125+ degrees in the summer. i have two big though the wall ac units, one 14000 BTU and the other 18000 BTU, ofcourse there both 220 volts. i have a 5500 WATT generator and wondered if i could possible run one one of these units off my generator if our electric goes out, which it does from time to time. im having a hard time finding out the amp draw for either unit just that there both 220 volt. they each are connected to dual 20 amp breakers. will my 5500 WATT generator be able to run one of these units ?

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Old 08-13-2012, 06:50 PM   #2
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i live in a area of arizona there temps get to 125+ degrees in the summer. i have two big though the wall ac units, one 14000 BTU and the other 18000 BTU, ofcourse there both 220 volts. i have a 5500 WATT generator and wondered if i could possible run one one of these units off my generator if our electric goes out, which it does from time to time. im having a hard time finding out the amp draw for either unit just that there both 220 volt. they each are connected to dual 20 amp breakers. will my 5500 WATT generator be able to run one of these units ?
If the surge rating is decent enough on the generator it should handle it, why not try it out and be sure?

Also, just look at the nameplate, all the info will be on that.

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Old 08-13-2012, 07:01 PM   #3
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running AC unit off generator


it list my surge at 8550 WATTS. dont really want to try it out in case of a overload and might cause a problem in the ac or generator. kinda of like = im not sure if ill break my leg jumping off my roof, hey why not try it and see, what could be the worse case scenario.
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Old 08-13-2012, 07:09 PM   #4
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it list my surge at 8550 WATTS. dont really want to try it out in case of a overload and might cause a problem in the ac or generator. kinda of like = im not sure if ill break my leg jumping off my roof, hey why not try it and see, what could be the worse case scenario.
You trust your utility company? The same results could occur... seriously, the worst thing that happens is that it wont start.
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Old 08-13-2012, 07:40 PM   #5
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running AC unit off generator


the condensers are the load so total up the amps on both and multiply X volts for a general idea of the watts. definitly start one then do the other after couple of minutes to test run.keep in mind the air handler/evap section might come off a seperate breaker add in those watts...formula AMPS X VOLTS = WATTS

Last edited by biggles; 08-13-2012 at 07:42 PM.
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Old 08-13-2012, 08:24 PM   #6
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running AC unit off generator


youve got it biggles, problem is finding out the amp draw. its not listed on the unit or in the owners manual, strange. but seeing as my 220 volt on my generator is only 30 amp. as for the worse case = burn out something in the ac. seeing as the unit is running off 2 = 20 amp breakers and the generator has a 220 thats only 30 amps, well thats a little short, if it had a 40 amp out then id give it a try. otherwise im going to have to continue to try and find out the amp pull, loaded and unloaded, of my ac unit. i do have one of those meters that clamp around the cable, maybe it will tell me the amps, when running and when the compressor kicks on, to make sure it doesnt exceed the output of the generator. to rig it up the way i want, electrical box and switch and wire, will cost a few bucks and dont want to waste money on something just to find out it doesnt work. i searched the internet to find the specs on the ac but nothing, other than the BTUs and voltage.
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Old 08-13-2012, 08:29 PM   #7
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running AC unit off generator


does this statement sound right ======All the Air conditions do not have 15 Amps (amperes) to work. The Amps means the volume of flow of electricity. The Amps depends on its BTU (British Thermal Unit). BTU is the unit to measure the energy that is consumed to perform some Air Conditioner. 12000 BTU Air conditioners uses 5 to 6 Amps. 18000 BTU Air conditioners uses 9 to 10 Amps. 12000 BTU air conditioners also called 1 Ton AIR CONDITIONER and 18000 BTU Air conditioners are called 1.5 Ton and so on. The 2 Ton or 24000 BTU Air conditioners use 15 Amps to work.
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Old 08-14-2012, 05:09 PM   #8
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running AC unit off generator


I'd just use your clamp ammeter, multiply by 240 and be done with it. I think that if these are typical AC units you should be able to run both of them continuously with your generator. If they start cycling, you might overload if they both start at the same time so you might have to run them in a way so that only one is cycling if you want to cool both areas at the same time.

Last edited by ionized; 08-14-2012 at 05:22 PM.
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Old 08-14-2012, 05:18 PM   #9
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running AC unit off generator


If you're that concerned, go pickup one of those 5,000BTU units for $129 from Walmart or Home Depot and keep it in the basement or garage. In the case of a power outage, throw it in the living room window or a bedroom window and close the door, everyone can hang out there when they want to keep cool. Not only will it definitely work with your generator, but it will consume a lot less power than your big units which means you'll be able to run a lot of other stuff along with the AC unit. You want to keep your fridge going (maybe 2 of them?), a couple TV's, some lights, computer and modem/router, etc.
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Old 08-14-2012, 05:24 PM   #10
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running AC unit off generator


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Originally Posted by hotrod351
does this statement sound right ======All the Air conditions do not have 15 Amps (amperes) to work. The Amps means the volume of flow of electricity. The Amps depends on its BTU (British Thermal Unit). BTU is the unit to measure the energy that is consumed to perform some Air Conditioner. 12000 BTU Air conditioners uses 5 to 6 Amps. 18000 BTU Air conditioners uses 9 to 10 Amps. 12000 BTU air conditioners also called 1 Ton AIR CONDITIONER and 18000 BTU Air conditioners are called 1.5 Ton and so on. The 2 Ton or 24000 BTU Air conditioners use 15 Amps to work.
No.

Current to the motor will vary by compressor size and design. Super efficient ones will have lower current draw as same sized less efficient units. Also these loads are quite reactive so simple V X I is not watts. There is a power factor to consider. The generator will likely be limited by peak voltamps (VA) and not watts due to PF of the load.

The best idea is to just try it. See if the generator can deliver the start up current surge without stalling or popping a breaker.
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Old 08-14-2012, 06:04 PM   #11
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running AC unit off generator


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youve got it biggles, problem is finding out the amp draw. its not listed on the unit or in the owners manual, strange. but seeing as my 220 volt on my generator is only 30 amp. as for the worse case = burn out something in the ac. seeing as the unit is running off 2 = 20 amp breakers and the generator has a 220 thats only 30 amps, well thats a little short, if it had a 40 amp out then id give it a try. otherwise im going to have to continue to try and find out the amp pull, loaded and unloaded, of my ac unit. i do have one of those meters that clamp around the cable, maybe it will tell me the amps, when running and when the compressor kicks on, to make sure it doesnt exceed the output of the generator. to rig it up the way i want, electrical box and switch and wire, will cost a few bucks and dont want to waste money on something just to find out it doesnt work. i searched the internet to find the specs on the ac but nothing, other than the BTUs and voltage.
The manufacturer's data definitely says what the current draw or wattage is. You're just missing it. It's there somewhere - probably even on a label on the unit itself. Regardless, you will definitely be able to run at least one unit at a time on that generator, and probably both at the same time. The only way to know for sure is to try it. We keep telling you to try it and see, and you keep not doing it. Go try it. The worst that happens is that the breaker trips or the generator stalls.
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Old 08-14-2012, 06:05 PM   #12
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running AC unit off generator


i started thinking that my 5500 watt will do the ac and i could get a cheaper 2 or 3 thousand watt to power my place, then again bigger is always better and with prices around $600.00 for a continuous 5000 watt generator that would be the way to go, have two big 5000 watt units. tell yea when its 125 + out $600.00 would sound cheap.
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Old 08-14-2012, 06:21 PM   #13
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running AC unit off generator


Bigger will use more fuel at part load and idle. It is more fuel efficient to have a generator matched to the load. If you are using gasoline fuel, you have to haul a lot.
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Old 08-14-2012, 07:46 PM   #14
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running AC unit off generator


its not like the electric is off for days, hours. i was looking at a couple generators that run on propane, seeing as i do roofing and torch down is one of the roofs i do, i always have a couple of 5 gallon bottles that have some in them. would also be better on the carb, seeing as it wont get any residue in the bottom from sitting, and i do run my engine out of gas when done. it just seems that all the generator, or most under $800.00, have a running of 5000 watts and a surge of anywhere from 7000 watts to 8500 watts. the one i have now has a 5550 running and a surge of 8500.
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Old 08-14-2012, 08:00 PM   #15
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youve got it biggles, problem is finding out the amp draw. its not listed on the unit or in the owners manual, strange. but seeing as my 220 volt on my generator is only 30 amp. as for the worse case = burn out something in the ac. seeing as the unit is running off 2 = 20 amp breakers and the generator has a 220 thats only 30 amps, well thats a little short, if it had a 40 amp out then id give it a try. otherwise im going to have to continue to try and find out the amp pull, loaded and unloaded, of my ac unit. i do have one of those meters that clamp around the cable, maybe it will tell me the amps, when running and when the compressor kicks on, to make sure it doesnt exceed the output of the generator. to rig it up the way i want, electrical box and switch and wire, will cost a few bucks and dont want to waste money on something just to find out it doesnt work. i searched the internet to find the specs on the ac but nothing, other than the BTUs and voltage.
You should be able to run one. AC is running on a 20 amp breaker and generator has a 30 amp breaker.

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