Starting watts on a 8000 btu window unit

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I’m sizing what I can and can’t run on another small inverter generator I picked up after selling my last clunky Troybuilt.

GE window unit ac I’m looking at says 6.1 amps 120 volt. I’m thinking that’s running amps, not starting amps based on the generic numbers I’m finding on-line.

Any help? @BlackGun @Friday
 
rdinatal said:
They should have 'peak' or 'starting' vs. 'continuous' in the detailed user guide or manual. What's the model?
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Haven’t bought it yet. My other new appliances only list amps and volts with no distinction As to starting or running in the manuals.
 
You will want to look for lra (locked rotor amps)

From there you can figure out the watts
 
LeeMajors said:
You will want to look for lra (locked rotor amps)

From there you can figure out the watts
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this is what GE has to say about that, so apparently that info is not available on a window unit.
AIR CONDITIONERS - LRA RATING
Locked Rotor Amps (LRA) is not a standard rating for Room Air Conditioners certified to UL 484. Locked Rotor Amps is only reported if the product is permanently connected (not cord connected) and exceeds specified electrical limits.

Any other research I have done on-line points me to the label on the appliance that lists model #, serial #, amps and volts. Nothing pertinent appears in the manuals.
 
Sounds like they're trying to dodge the question by hiding behind an NEC loop hole of being cord connected.

Absent name plate data, the rule of thumb would be 6x the full load current, or in your case 36-37 amps.
 
noway2 said:
Absent name plate data, the rule of thumb would be 6x the full load current, or in your case 36-37 amps.
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That seems like a lot. Most of what I read in general is saying 2x.

This is a one room ac. My clothes dryer is on a 30 amp breaker, as is my whole house AC for 2400 feet.
 
Buy a watt meter at home Depot ant test the AC when plugged in to the house. You can return the meter later. I estimate 1/3 additional to start. Newer units use smaller compressors to run on modern refrigerant.
 
Button Pusher said:
Buy a watt meter at home Depot ant test the AC when plugged in to the house. You can return the meter later. I estimate 1/3 additional to start. Newer units use smaller compressors to run on modern refrigerant.
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I need to know the specs before I buy the ac because if my Honda 2200 generator can’t handle the load, I’m not buying the ac.

The breakers for the bedroom receptacles in this new house are 20 amp so in my feeble mind that means they should handle 2400 watts. If the window unit is rated at 6.1 amps, and it pulls three times that (a WAG) when the compressor kicks in that’s still only 1800 watts surge and 732 running.
 
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And since this will be running off an extension cord to the inverter generator, I need to get a proper sized extension cord. I’m thinking (hoping ) 15 amp, but might need 20.

...and I just ordered a 50 ft 15 amp yesterday.
bah
 
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fieldgrade said:
That seems like a lot. Most of what I read in general is saying 2x.

This is a one room ac. My clothes dryer is on a 30 amp breaker, as is my whole house AC for 2400 feet.
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6X is not unrealistic. Remember the LRA rating is only for a few milliseconds. Once it starts to rotate, the current (and therefore wattage) drops off exponentially with time. Starting current is much higher than most believe. With a small motor, it only lasts a few milliseconds. A regular meter will never see the actual starting current. The only way I can see it, is with an oscilloscope and clamp. I don't have any fancy power meters, but it works well for what i need.

Sent from my SM-N975U using Tapatalk
 
jodyisaacs said:
6X is not unrealistic. Remember the LRA rating is only for a few milliseconds. Once it starts to rotate, the current (and therefore wattage) drops off exponentially with time. Starting current is much higher than most believe. With a small motor, it only lasts a few milliseconds. A regular meter will never see the actual starting current. The only way I can see it, is with an oscilloscope and clamp. I don't have any fancy power meters, but it works well for what i need.

Sent from my SM-N975U using Tapatalk
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How would a 6.1 amp 120 volt one room ac run on a 20 amp room receptacle circuit if that is true?

corrected 15 amp to 20 amp
 
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Also, that starting current does not really affect the wire size, as the wire sized for the correct running current will carry the surge with no problem. The breaker will not trip, as it is a heat and time thing. The higher the draw, the less time before it heats up and trips. That's why you can't consistently run 20A from a 20A breaker, but it will run for quite some time before tripping.

Sent from my SM-N975U using Tapatalk
 
fieldgrade said:
How would a 6.1 amp 120 volt one room ac run on a 20 amp room receptacle circuit if that is true?

corrected 15 amp to 20 amp
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It's high current for such a short time, the breaker doesn't have time to "heat up" to trip point, before the current falls off to normal.

Sent from my SM-N975U using Tapatalk
 
That's a difficult question to ask, because if you look with a small enough time measurement, the current is almost infinite. There's a lot of specsmanship in all of this.

I'd think that you will be fine....the generator tolerates short term overloads. You could minimize that if it's an issue by starting the fan, then starting the compressor (Fan only start, then switch in compressor)
 
jodyisaacs said:
Also, that starting current does not really affect the wire size, as the wire sized for the correct running current will carry the surge with no problem. The breaker will not trip, as it is a heat and time thing. The higher the draw, the less time before it heats up and trips. That's why you can't consistently run 20A from a 20A breaker, but it will run for quite some time before tripping.

Sent from my SM-N975U using Tapatalk
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That is true (the trip time) . Trip curve specs are interesting to read as you say (particularly if you're a geek and/or in the business of making and testing these things!)

I can tell you that modern (last 10 yrs?) , quality breakers do have a thermal/magnetic component actuator mechanism BUT they also have a line powered ASIC inside that is running software analyzing what's going on with with I-V waveforms. As time goes on, you'll see less and less of the former and more and more of the latter. The manufacturers (one of which I worked for) snuck all this electronics while you weren't looking , in the same form factor as the older thermal-mag breakers.

GFI/AFI functions are all implemented mathematically.
 
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The other piece that I didn’t mention is that I bought this small Honda generator mainly to run the 1.5 amp refrigerator, and it sounds like there’s no way to run the 8000 btu one room window unit without unhooking the frig for longer than I’d want to.
 
JohnFreeman said:
That is true (the trip time) . Trip curve specs are interesting to read as you say (particularly if you're a geek and/or in the business of making and testing these things!)

I can tell you that modern (last 10 yrs?) , quality breakers do have a thermal/magnetic component actuator mechanism BUT they also have a line powered ASIC inside that is running software analyzing what's going on with with I-V waveforms. As time goes on, you'll see less and less of the former and more and more of the latter. The manufacturers (one of which I worked for) snuck all this electronics while you weren't looking , in the same form factor as the older thermal-mag breakers.

GFI/AFI functions are all implemented mathematically.
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Hello, fellow geek! Lol... times, they are a changin'...I never thought I would see the day that breakers and outlets would have solid state devices, ASICS, PGAs, etc., internally. I deal predominantly with machinery... overloads, motors, servos, manual motor starters, contactors /relays, PLCs, and drives. It amazes me how far this stuff has come in the 30+ years I've been doing it. In the olden days, I would spend a day wiring in a bunch of relays, and make it run. Now, you can buy a number of PLCs for less than $100 bucks, write a program in 30 mins, and you're running. If you need to make a change, it's a simple code change, instead of 4 hours of wiring, and hoping you got it right the first time.

Sent from my SM-N975U using Tapatalk
 
I have a new 5k that I bought to run off a little Honda 2000watt. If I lose power in the summer I can cool at least one small room.
Never tried it but I hope it works:)
 
fieldgrade said:
The other piece that I didn’t mention is that I bought this small Honda generator mainly to run the 1.5 amp refrigerator, and it sounds like there’s no way to run the 8000 btu one room window unit without unhooking the frig for longer than I’d want to.
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I’ve been thinking about buying another 2000k Gen for the same reason. Will buy the HF one this time.
 
There's another potential complication, especially since you mentioned it is an inverter generator, and that is power factor. Power factor is defined as the cosine of the phase angle (time lag between the peaks) between the voltage and current(*). Typically the power factor for a running motor is going to be somewhere around .8 and it will be different during start with a single phase motor that likely has a start capacitor. This has two impacts. One, the actual current required will be higher than the wattage indicates. Two will be the inverter's capability of potentially sourcing into a low power factor load.

* - This gets into an area that many might call funky math involving derivatives and complex / imaginary numbers, but basically the motor winding will have a resistance and reactance (inductance and capacitance). Being AC power the voltage is a sine wave and the component of the current from the reactance is 90 degrees, or 1/4 wave, out of phase (time) with the resistance component. This has the effect of making the inverter supply more current at a time when the voltage is lower, which is harder for it to do and there is a limit to how far off it can be.

The TLDR version of this being it will be harder for the generator to run a motor than it would an electric heater of the same wattage.

Running the AC unit probably won't be a problem, whether or not the generator will start it may be. Then again, the little generator I have will run the fridge, freezer, and fan motor on the downstairs (gas furnace) air handler just fine.
 
Majicmike said:
I have a new 5k that I bought to run off a little Honda 2000watt. If I lose power in the summer I can cool at least one small room.
Never tried it but I hope it works:)
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This is what I want to do, but while running the frig, and I am thinking that might be too much. Frig is 1.5 amp, and ac I’m looking at is 6.1, to run on a Honda 2200, which is max watts (2200).
 
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fieldgrade said:
This is what I want to do, but while running the frig, and I am thinking that might be too much. Frig is 1.5 amp, and ac I’m looking at is 6.1, to run on a Honda 2200, which is max watts (2200).
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I would say it would be very hard on it if it even would trying to run both at same time. I think it would run one or the other and chances are you may not need to run both at same time any way unless your just in and out of fridge alot during a power outage.
 
Jp8819 said:
I would say it would be very hard on it if it even would trying to run both at same time. I think it would run one or the other and chances are you may not need to run both at same time any way unless your just in and out of fridge alot during a power outage.
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FDA says run the frig every four hours to keep food safe. I have no idea how much overkill that is, but I’d like to run the AC in a bedroom at night should the need arise during hurricane season.
 
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fieldgrade said:
FDAs says run the frig every four hours to keep food safe. I have no idea how much overkill that is, but I’d like to run the AC in a bedroom at night should the need arise during hurricane season.
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I have never looked at recommended time periods just know i have gone 6-7 hrs+ on one overnight as long as your not opening the door and the items in it were already cold and not gotten sick good or bad :) . I wouldnt want to push it to much or keep things in it as long that are already open doing it. I have also helped freezer keep longer By having a jug of water frozen in it prior to power outage but that requires room in freezer which is not usually easy to come by.
 
Good information here, I always walk away a bit smarter after visiting CFF.
 
fieldgrade said:
this is what GE has to say about that, so apparently that info is not available on a window unit.
AIR CONDITIONERS - LRA RATING
Locked Rotor Amps (LRA) is not a standard rating for Room Air Conditioners certified to UL 484. Locked Rotor Amps is only reported if the product is permanently connected (not cord connected) and exceeds specified electrical limits.

Any other research I have done on-line points me to the label on the appliance that lists model #, serial #, amps and volts. Nothing pertinent appears in the manuals.
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I looked at 3 here on the property and all 3 have lra rating (2 were bought within the last 2 months).


Anyway the lra on a 12k in 14.3a

That's said I dont see why your little genny wouldn't run both
 
SPST said:
Buy another Honda generator and parallel it to the one you have.
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Don’t want to if I don’t need to.

They are on sale, but that’s still another grand with tax.
 
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I hit the net and found this blurb from GE, nothing you didn't already know...important stuff is the 2x running power is approximate starting wattage. I had my warehouse guy go check a rating plate on a new 8k BTU GE window unit in my warehouse. 115V, 695 Watts

ac.JPG
 
fieldgrade said:
This is what I want to do, but while running the frig, and I am thinking that might be too much. Frig is 1.5 amp, and ac I’m looking at is 6.1, to run on a Honda 2200, which is max watts (2200).
Click to expand...


So... fridge is ~ 180 watts, AC is ~750. You're at 900 and change on a 2200 watt gennie?

I think you should be fine.
 
JohnFreeman said:
So... fridge is ~ 180 watts, AC is ~750. You're at 900 and change on a 2200 watt gennie?

I think you should be fine.
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2200 surge watts, or whatever they call it, 1800 otherwise, and the frig probably draws 2x the 1.5 amps when the compressor starts, likewise the 6.1 amp a/c
 
jodyisaacs said:
Hello, fellow geek! Lol... times, they are a changin'...I never thought I would see the day that breakers and outlets would have solid state devices, ASICS, PGAs, etc., internally.
Click to expand...

You can do a lot of stuff with some very inexpensive ASICs (especially if you are buying 20 million or so a year to leverage price).

We did a ton of testing on them evaluating the algorithms to make sure we weren't shipping products that would kill people by not tripping or turn their house dark everything someone drove by with a CB or a cell phone on.
 
fieldgrade said:
2200 surge watts, or whatever they call it, 1800 otherwise, and the frig probably draws 2x the 1.5 amps when the compressor starts, likewise the 6.1 amp a/c
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Yep, but it only pulls that for fractions of a second ..... so even if they started at the same time (unlikely but possible) you should have enough headroom.
 
JohnFreeman said:
Yep, but it only pulls that for fractions of a second ..... so even if they started at the same time (unlikely but possible) you should have enough headroom.
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I was using a factor of 2x. At least two others above quoted 6x, at least on the ac.

If the generator is not putting that much out, what kind of problems can that cause?
 
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Majicmike said:
I know it’s Ash’s thread but my back up plan for a sustained loss of power is almost full proof.
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During Hurricane Fran I just packed up my 9 months pregnant wife after three days and went to my parent's house in Charlotte.
She’s in a retirement home now, my mom that is, so that ain’t gonna work for me.

So what’s the foolproof plan, I mean ALMOST foolproof. ;)
 
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fieldgrade said:
During Hurricane Fran I just packed up my 9 months pregnant wife after three days and went to my parent's house in Charlotte.
She’s in a retirement home now, my mom that is, so that ain’t gonna work for me.

So what’s the foolproof plan, I mean ALMOST foolproof. ;)
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Pretty much the same thing. Our longest range vehicle is my wife’s car. Appx 450 on a tank of gas. I always make sure I have enough gas at home to fill the car. Keep enough cash nearby where we can stay in at hotel for a month well west of the affected area. As long as I can afford it I’ll NEVER do another Fran like power outage.
 
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