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What Size Generator Do I Need For My House?

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Power outages can be frustrating, especially if they frequently happen at your Chesterfield, MO area home. If you have medical devices that always require power to operate or worry about the food in your chest freezer thawing and rotting a standby generator might be the best solution for your home. Backup or whole house generators are appliances that can power your home the minute the power goes out.

Chesterfield Service is proud to provide whole house generator services including installation, maintenance, and repairs. Knowing how to determine the right-sized generator for your home can help make the purchasing process easier and give you peace of mind knowing that all of your necessary devices will work during the next power outage.

How A Whole House Generator Works

A whole home generator is a large appliance that is housed outside of your home. It is housed in a metal container and is similarly sized to an air conditioner. It is connected to the home directly to the electrical panel. When there is a power outage, the generator provides power to the electrical panel by using either natural gas or liquid propane to start its alternator, which converts mechanical energy produced in the generator’s combustion engine into electricity. One advantage to whole-home generators is that they run much quieter than portable generators.

Many generators have an automatic transfer switch that instantly detects when power has been lost. If no one is occupying the home during a power outage, the home standby generator will still kick on to preserve your home’s electrical appliances and equipment.

How To Choose A Standby Generator

Having a source of backup power for your home can bring you peace of mind. There are many different kinds of home standby generators, and you will have to put some thought and do some math to figure out which one would be best for your home. The team at Chesterfield Service has the steps you need to take when you start shopping for a backup generator.

Make a List of Appliances

When figuring out what size generator I need for my home, a good place to start is a list of priorities. Do you want your whole house to have electricity, or do you just need a few things to have power? Power outages often are caused by storms, and a particularly cold ice storm can leave you without heat. This can be especially dangerous during prolonged power outages. A whole home generator can keep the heat on in your home, but your HVAC system will require most of the power created by the generator.

Start by making a list of essential appliances that you need to run during a power outage like your home’s HVAC system, water heater, refrigerator, and freezer. The system’s wattage needs are usually listed on a label on the appliance or in the owner’s manual, but here is a list of some normal appliances and their system wattages:

  • Electric Furnace: 5000-25000
  • Central Air Conditioner: 2000-4000
  • Water Heater: 3000-4500
  • Sump Pump: 1500
  • Refrigerator/Freezer: 600-800
  • Microwave: 1200
  • Television: 100-350
  • Personal Computer: 500-2000
  • Space Heater: 1250
  • Table Lamp: 150

Starting Wattage

Once you make a list of the appliances you want to be able to use during power outages, add up all the wattage requirements. This calculation is your “running wattage.” However, appliances require more power to start up. You need to account for this surge in power when considering generators. This is called the “starting wattage,” and to figure out the starting wattage, multiply your running wattage by 3.

Generator Capacity

Most owner’s manuals for generators will include an example of the types of appliances they can run, but it’s always good to do the math yourself. To find your total wattage, you need to add your “running wattage” and the “starting wattage.” However, if your total wattage is 4000, don’t pick a generator with a capacity that’s the exact same number. To ensure proper performance, you should use no more than 90% of your generator’s load capacity.

Fuel Source

Many homeowners connect their standby generators to natural gas lines. This ensures that your generator will kick on automatically without needing to refuel. However, if your home is not connected to a municipal gas line, then you may need to find another source of fuel. Liquid propane is another common fuel source for generators. During very prolonged power outages, it is possible to run out of fuel. A dual-fuel generator can use liquid propane or gasoline as well as natural gas. They can be more environmentally friendly and energy efficient than a single-fuel generator. Many systems can automatically switch between fuel sources when they reach low fuel levels.

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