Can A Portable Generator Run A Central Air Conditioner?

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Central air conditioning is a great way to maintain a comfortable climate in your home. If a storm, power surge, or local electrical outage affects your home, however, you might be left without the use of the utility systems. Home generators can help to keep up some things like well water pumps running, but what about your air conditioner? Central air conditioning units use up a lot of energy, so it's natural to wonder if portable generators can keep those systems online. We've researched this to find the answer for you.

Yes, a portable generator can power your central air conditioning unit. Portable generators are not just for powering small appliances; they can keep energy-intensive home systems running during power outages as well. You need to make sure you pick a portable generator strong enough to run the air conditioning unit and any other essential systems you plan to plug into it. 

We've gathered together everything you need to know on how to run your central air conditioning units off of a portable generator. Read more to learn what kind of generator solution you need to keep your central air conditioning running when the power goes out!

HVAC heating and air conditioning units, Can A Portable Generator Run A Central Air Conditioner?

How Does It All Work?

You often think of portable generators to keep small low-power appliances running when the power goes out. The reality is, one of the most common uses for a portable generator is to keep essential home systems operating when there is an electrical problem at home.

Generators come in a massive variety, differentiated mainly by their electrical production capacity and battery life duration. The wattage of a generator determines its power output, and the basic rule is to buy a generator with at least a slightly higher wattage output than the air conditioner needs.

Starting Wattage & Running Wattage

The most important numbers that you need to pay attention to are the starting wattage and running wattage. When a generator kicks on, it needs more power to begin operations. You need to make sure that the wattage output from the generator can handle the higher starting wattage, so nothing gets damaged.

It's important to check these figures for anything else you'd want to simultaneously power on the same generator to prevent any failures. To keep your cooling systems running without issues, be sure to check out our article, " How Long Should A Central AC Run At A Time?"

Power Transfer Switch

Automatic transfer switch for sale in the store

The process of connecting your central AC to a portable generator as a backup needs some careful attention. If you don't already have a power transfer switch between your furnace and central circuit breaker, then you will need to have an electrician install one.

That way, power can be routed into the system from a generator that you can plugin. This step in the process will allow you to connect your generator. Since it involves very dangerous electrical wiring should be left to a professional.

What Size Generator Do I Need to Run a Central Air Conditioning Unit?

Residential house natural gas backup generator

The generator you need to run your central air conditioning unit is based on your cooling system's wattage needs. Size can indicate a generator's power, but it's not a reliable indicator of how powerful it is.

Always check with your exact unit for the wattage expenditure. Never rely on an estimate or what you think sounds right. If you overload your generator, you can cause it to fail, the cooling system to blow out, or even the generator to catch fire.

Determine the Generator Wattage & Appliances Needing to be Run

Once you have determined both the starting and running wattage of your central air conditioning unit either from the manufacturer, or the nameplate on the unit itself, you can use that number to find a generator that would work. You also need to identify what other appliances you might run with your air conditioning unit.

Take note of all the starting and running wattage needs and add them together. Once you have a number that is at least the starting wattage of everything you need to power, you can find a generator with at least that much energy output.

As an example, assume you have a fairly common modern energy-efficient AC unit. The average unit uses about 3,500 W of energy per hour. The starting wattage might be something slightly higher, like 4,000 W. If you reserved the use of this generator only for air conditioning, you would need a portable generator with at least 4,000 W of power.

This WEN generator provides 6,000 Watts and can be found on Amazon. 

Can a Portable Generator Run a 2.5 Ton AC Unit?

Portable electric generator


It is always better to remain on the safe side and get a more powerful generator than you need to run your central air conditioning systems. You really wouldn't want to risk permanently damaging your systems or worse because you didn't just opt for a better option.

Most people recommend using a 10,000 W generator to power a 2-ton or 2-1/2-ton air conditioner. The weight here refers to the amount of air pressure or BTU the unit needs to cool a space properly.

Portable generators have developed over the years to be able to power all kinds of appliances and systems. Generic manufacturers produce portable generators with up to 17,500 Watts of power. This much power would be able to comfortably power several systems and appliances together for some time. However, the problem with portable generators is that their mobility causes them to be much more expensive.

How Many Watts Does Central AC Use?

Two central air conditioning units set up outside a single storey house

How much electricity a central air conditioning unit uses is based on a few variables. Newer and more energy-efficient systems will use much less power draw than older, less maintained AC units. The weight or BTU pressure needed to cool the home space is the main component in determining the power draw of a cooling system.

If your cooled area is very large, the air conditioner needs to operate at a higher energy cost to pump the air through the space and maintain the temperature. The average Central AC unit uses around 3,500 W of electricity or 12,000 BTUs every hour.

To be on the safe side when selecting a portable generator to pair with this average standard, you should opt for something with about 6,000 to 6,500 Watts of output. Wall air conditioning units use less energy and are less efficient but are easier to run from a portable generator due to their lower electrical drain.

To learn more about how powerful your window AC with a generator works, check out our article, "What Size Generator Do I Need To Run A Window Air Conditioner?"

Will a 2,000-Watt Generator Run an Air Conditioner?

A Honda EU 2000i Inverter generator

A 2,000-watt generator would likely not be able to run any air conditioning system. The energy needed to cool and push air through virtually any space would need more electrical power output than 2,000 watts per hour.

Even individual window units would still be best kept on a portable generator with 3,000-4,500 watts. Portable generators with low wattage are meant for smaller appliances used in emergencies until the power turns back on. Major home systems like water pumping and climate control would not be able to run on a setup with such a low-powered generator.

You Have Options

Two air conditioning units set up properly outside a modern house, Can A Portable Generator Run A Central Air Conditioner?

Portable generators can take a lot of stress off of your mind as a homeowner. Power outages or electrical problems are mostly random and unavoidable. Having a capable generator that can be used as needed to keep your home's essential systems is invaluable.

You just have to keep in mind what power output you need the generator to have to power all the appliances you would need in an emergency. With a little bit of research and preparation, you can choose the perfect portable generator to keep you cool when difficult and unexpected problems arise!

This Post Has One Comment

  1. GenMaxDan

    Thank you for the information. The generator site I visited had a lot about generators and power station. It seem your content complements what they have going on there. Thanks so much again. I know now what will be best for our summer barn.

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