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So how many kW does a 2 ton ac use?
Posted on 10/29/20 at 3:57 pm
Posted on 10/29/20 at 3:57 pm
Any idea? Google searches give me different answers.
Posted on 10/29/20 at 5:27 pm to LSUlove
Cooling phase? If so, and this is one you own can you check the tag (label) on the condensing unit outside for the amperage draw of the compressor + fan, it should be on that tag. For example, my 4-ton unit draws right at 20 amps (compressor + fan) - that information is on my condensing unit tag, but I’ve also checked it with an amp meter when the unit is operating and the values are very close.
Watts = amps x voltage. So 20 amps x 230 volts = 4,600 watts or 4.6 kW per hour while “running”. Add to that the amp draw of the blower motor in the air handler - not sure what that is without going into my attic and checking the motor but it’s not high, so maybe 5 kWh for my 4 ton unit for each hour of operation.
Heating - do you have electrical heating elements or natural gas? If natural gas, then just what the air handler blower motor uses - which again is not high. Electrical heating elements - add whatever watts or KW the elements are rated at for your unit.
That should get you pretty close. I’m not an engineer so engineers on the board will have to correct my math if I’m in error.
P.S., Now there is high in-rush amperage draw when the compressor starts which will up the numbers above somewhat - not sure how that is added in as that amperage draw, and hence kW consumption, is only for milliseconds.
Watts = amps x voltage. So 20 amps x 230 volts = 4,600 watts or 4.6 kW per hour while “running”. Add to that the amp draw of the blower motor in the air handler - not sure what that is without going into my attic and checking the motor but it’s not high, so maybe 5 kWh for my 4 ton unit for each hour of operation.
Heating - do you have electrical heating elements or natural gas? If natural gas, then just what the air handler blower motor uses - which again is not high. Electrical heating elements - add whatever watts or KW the elements are rated at for your unit.
That should get you pretty close. I’m not an engineer so engineers on the board will have to correct my math if I’m in error.
P.S., Now there is high in-rush amperage draw when the compressor starts which will up the numbers above somewhat - not sure how that is added in as that amperage draw, and hence kW consumption, is only for milliseconds.
This post was edited on 11/5/20 at 8:49 am
Posted on 10/29/20 at 5:52 pm to CrawDude
Lol, way over my head. Trying to figure out if I can run my 2-ton ac on a 12,000kw (running) gen along with my fridge and freezers. Also how much wattage I would have left over if any. I currently have a 5500 gen that I have powering 3 fridge/freezer plus lights, fans, tv that doesn’t appear to be strained at all.
Posted on 10/29/20 at 6:17 pm to LSUlove
It will probably run the AC unit but it may put you over the top if you have other things plugged in when the AC unit kicks on.
This post was edited on 10/29/20 at 6:19 pm
Posted on 10/29/20 at 6:25 pm to LSUlove
I got you. Well the 12,000 watt gen set in 230 volt mode is in theory going to be handle about 50 amps (12,000 divided 230) but in a practical sense maybe 80% of or 40 amps. That’s likely enough to “run” your 2 ton unit.
The problem is the starting or in-rush amps, which is much higher, even for a brief second, when the compressor kicks on. That will be more in line with the LRA (locked rotor amps) on the outdoor compressor tag. A hard start capacitor or soft start capacitor installed in the outdoor condensing unit can help with that. Remember my example above of my unit, 4-ton with a rated load amps (RLA) of 18.3 but a LRA of 109. A 12000 watt generator can “run” my unit but not start it.
Now that others know what you are trying to do, they can weigh in with better information, knowledge and experience than me - I’m curious myself what the answer is but it will help if you go outside and get the RLA and LRA information off the condensing unit tag - it will be there, and add that info to your OP. Thats really the important info needed to answer your question.
The problem is the starting or in-rush amps, which is much higher, even for a brief second, when the compressor kicks on. That will be more in line with the LRA (locked rotor amps) on the outdoor compressor tag. A hard start capacitor or soft start capacitor installed in the outdoor condensing unit can help with that. Remember my example above of my unit, 4-ton with a rated load amps (RLA) of 18.3 but a LRA of 109. A 12000 watt generator can “run” my unit but not start it.
Now that others know what you are trying to do, they can weigh in with better information, knowledge and experience than me - I’m curious myself what the answer is but it will help if you go outside and get the RLA and LRA information off the condensing unit tag - it will be there, and add that info to your OP. Thats really the important info needed to answer your question.
This post was edited on 10/29/20 at 6:35 pm
Posted on 10/29/20 at 7:05 pm to CrawDude
It’s a 15000kW starting and 12000kW running. If that helps. I’ll try to get that info to add to OP. Appreciate the answers!
Posted on 10/29/20 at 7:34 pm to LSUlove
Go to one of the generator websites, they have calculators, just plug in what you have.
Posted on 10/29/20 at 7:44 pm to LSUlove
quote:
It’s a 15000kW starting and 12000kW running. If that helps. I’ll try to get that info to add to OP. Appreciate the answers!
OK, the 15,000 starting watts @230 volts brings the starting amps to 65 amps. If the locked rotor amps (LRA) on your condenser plate is less than 65 amps then the generator should be large enough to start and run the 2 ton unit, particularly if a hard or soft start capacitor is added to the condensing unit (easy and inexpensive) with likely sufficient amperage to run the other items you mentioned in your OP.
I’ll be interested to see what others think and say that have first hand experience with this, particularly after you post the LRA and RLA of your 2-ton Carrier.
P.S. should note if you run the 12,000 kw generator on natural gas or propane it won’t generate as much kw as if running on gasoline - so that will need to be accounted for as well. .
This post was edited on 10/30/20 at 8:31 am
Posted on 10/30/20 at 6:32 am to CrawDude
A 12 KW with 15 KW surge should be plenty enough to run a 2 ton central unit, fridge/freezer, and should have enough left over to run a good bit if not all of your lighting/ tv loads. Especially if you have LEDs. A hard start on the condenser would not be a bad idea to help with the startup surge.
Your problem is going to be feeding that thing. It will be very thirsty if it’s gas, especially if it’s a 3600 rpm unit. It will probably have an 18 to 20 hp motor, and burn close to 2 gallons an hour at rated load.
Your problem is going to be feeding that thing. It will be very thirsty if it’s gas, especially if it’s a 3600 rpm unit. It will probably have an 18 to 20 hp motor, and burn close to 2 gallons an hour at rated load.
Posted on 10/30/20 at 6:54 am to LSUlove
You should be fine. I back fed my whole house with a generac 6500 for 40 days without one single issue. I ran my 2.5 ton ac (set on 70) and everything else in my house except the water heater and stove. I bought a cheap microwave from Walmart instead of using my big built in. Trust me, my family was not being conservative at all with power consumption, we lived like we weren’t on generator power the whole time and never had a problem.
Posted on 10/30/20 at 8:18 am to LSUlove
probably around 1,700W or 1.7kW worst case. Due to inrush you'll want a slightly larger sized generator to handle the inrush during startup.
Any generator 3x larger should have no problems.
Any generator 3x larger should have no problems.
This post was edited on 10/30/20 at 8:20 am
Posted on 10/30/20 at 9:02 am to LSUlove
12KW will handle a 2 ton with ease and probably the rest of your house as well
Posted on 10/30/20 at 9:26 am to td1
Thanks so much for the replies. If converted to be fed off of natural gas, I know it lowers the kw ability, but I assume it would still be enough to run the ac? Just trying to prepare for the next time this happens and I don’t have the space around my house for a whole home.
Posted on 10/30/20 at 9:40 am to LSUlove
what is the derated value? I would think between 10-15%. Not a big deal usually.
Posted on 10/30/20 at 9:57 am to LSUlove
I’ve read up to 20% reduction in kW output converting a generator from gasoline to natural gas, Little to no reduction in kW output converting from gasoline to LP.
Posted on 10/30/20 at 10:15 am to LSUlove
I have a 2.5 ton heat pump. My Ridgid 6800/8000 Watt generator will run the A/C, fridge, freezer, television, DISH receiver and a couple of lights. The lights dim and the DISH receiver resets every time the A/C kicks on.
I just bought the Westinghouse 12,000/15,000 generator and only turn off the breaker for the electric water heater and range when it is running. It handles the rest of the house like a champ. Gas, on-demand water heater and gas range are on the way.
I just bought the Westinghouse 12,000/15,000 generator and only turn off the breaker for the electric water heater and range when it is running. It handles the rest of the house like a champ. Gas, on-demand water heater and gas range are on the way.
Posted on 10/30/20 at 11:58 am to LSUlove
delete
This post was edited on 1/11/21 at 12:55 pm
Posted on 10/30/20 at 2:48 pm to BiggerBear
That’s what I am looking at. So works good. Glad to hear it!
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