A 5000 watts generator is powerful enough to meet your basic needs during a power outage and that includes running your oil or gas furnace. If you have a forced-air electric furnace, it uses a lot more than 5,000 watts and you will NOT be able to run it on this size of a generator.
Everything else comes down to how much wattage you will require in total, meaning ALL the equipment and appliances running at EXACTLY the same time. The best way to maximize the efficiency of your generator is to manage your power usage properly.
It is NOT necessary to run your appliances during power outages all at once!
If you use a generator more efficiently, then it is possible that you will not require a lot of power and can get away with a smaller size (and cheaper) generator.
Appliance running and starting watts
Take care of your priorities first and they usually are:
- Refrigerator
- Air Conditioner or Furnace (depending on the season)
- Television
- Some lights
If those things will be running all at once, just write down their power usage and make space for some items that will NOT be used altogether (but one at a time):
- Microwave
- Electric stove
- Hair drier
- Toaster
- Coffee maker
- Etc.
How can a 5000-watt generator run a house? In addition to furnace usage, you need to know how much power you will be using in total.
By calculating your wattage use, you can know for sure if a 5000-watt generator is a proper size for you. Typical wattages of household appliances and devices are mentioned below (they are approximate, please read the label as well).
Electronics:
Devices | Watts (running) | Watts (surge) |
TV (82” LED) | 230 | |
Computer (desktop) | 80 | |
Computer (laptop) | 200 |
Small appliances:
Devices | Watts (running) | Watts (surge) |
Microwave | 1,450 | |
Blender | 300 | 900 |
Coffeemaker | 550 | 1,000 |
Slow Cooker | 200 | |
Rice Cooker | 200 | 500 |
Toaster (2-slice) | 800 | 1,600 |
Toaster (4-slice) | 1,150 | |
Food Processor | 350 | 500 |
Electric kettle | 1,200 | 3,000 |
Large appliances:
Devices | Watts (running) | Watts (surge) |
Refrigerator/Freezer (side-by-side) | 1,120 | 2,200 |
Freezer only (12 cu. ft) | 650 | 1,500 |
Electric dryer (clothes) | 750 | 1,800 |
Gas dryer (clothes) | 650 | 720 |
Dishwasher (cool dry) | 700 | 1,400 |
Dishwasher (hot dry) | 1,450 | |
Electric stove (8” range) | 2,100 |
Personal care:
Devices | Watts (running) | Watts (surge) |
Hair Dryer | 1,000 | 2,000 |
Iron | 1,000 | |
CPAP machine | 30-60 |
You will probably need some water heaters:
Devices | Watts (running) | Watts (surge) |
Water heater | 4,000-4,500 | |
Water Heater (Immersion) | 3,000 | |
Water Heater (Electric) | 2,000 | 3,000 |
Water Heater (Tankless) | 6,600 | 2,200 |
In a gas or oil furnace, basically, all you need to power is a blower fan, and it doesn’t require too much electricity:
Furnace fan | Running watts | Starting watts |
1/8 HP | 300 | 500 |
1/6 HP | 500 | 750 |
1/4 HP | 600 | 1000 |
1/3 HP | 700 | 1400 |
1/2 HP | 875 | 2350 |
Electric furnaces require a LOT more power and 5,000-generator will NOT be powerful enough to run it. Here are the ratings (again, the numbers are approximate):
Furnace fan | Running watts | Starting watts |
Central Electric Furnace (15 kW) | 15,350 | |
Central Electric Furnace (20 kW) | 20,490 | |
Central Electric Furnace (25 kW) | 25,670 |
Heat Pumps also use a lot of electricity:
Furnace fan | Running watts | Starting watts |
Heat Pump | 4,800 | 10,800 |
If having a big generator is NOT an option for you, the following devices can keep you nice and toasty during cold winter months:
Furnace fan | Running watts | Starting watts |
Electric Heater | 1,000 | 2,000 |
Space Heater (small) | 800 | |
Space Heater (large) | 1,800 | |
Electric Thermal Radiator | 500 | |
Electric blanket | 200 |
** Remember! ALL the above numbers are approximate. Please consult your manufacturer’s handbook or label.
Generator running and starting watts
As you probably noticed from above, the first rating is the “Running watts” (also called “Rated watts”) and “Starting watts” (also called “Surge watts”).
Starting watts are VERY important due to the fact that they can kick in at any time and use up all your power
Surge rating usually applies to motor-driven devices like refrigerators, air conditioners, pumps, etc. If you don’t pay attention to it, it can put you in an overload situation and your generator will shut down.
The best way to control your power is to:
- Connect all your MAJOR appliances to the generator and leave wattage space for 1-2 MINOR appliances
- Use your MINOR appliance and devices one by one (NOT at the same time) and turn OFF your MAJOR appliances while using them.
- If you really need to use many appliances, consider SOFT STARTERS
So, how do we check appliance wattage rating? Every device has a label on it and wattage is usually mentioned:
If it doesn’t mention watts, but you have amps and volts, all you need to do is multiply amps by wattage that you use in your country (110-120v in the USA for example):
Here is a how-to figure out the size of the generator that you need:
- Step 1. Choose your devices (that you need to run at the same time) and look up their wattage.
- Step 2. Break down wattage by Running (or Rated) and Starting (or Surge) watts.
- Step 3. Add all the Running (or Rated) wattage.
- Step 4. Find the highest Starting (or Surge) wattage device on your list.
- Step 5. Add this device to the TOTAL Running (or rated) wattage.
Here is the example for you:
Image source. Now, all you have to do is calculate to see if a 5,000-watt generator fits your needs.
VERY IMPORTANT! Generators also have SURGE WATTAGE. It is the maximum output that a generator can offer and only for a few seconds. Make sure that you are looking at the right ratings BEFORE your purchase your generator:
Very often generators are rated by SURGE WATTAGE, even though it lasts only a few seconds:
Surge wattage is important, but you need to make sure that the running wattage will accommodate your power needs as well.
Attention! This article is for informational purposes ONLY and is NOT a replacement for a professional advice! You will need to visit school's website for details and updates, as well as consult your local HVAC specialist for appropriate solution to your problem.
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