What size generator go I need?

Having power backup during a storm or another power outage causing event is essential in a modern home filled with devices running on electrical power. We normally don't pay much attention to how dependent we are on electrical power but during the time of crisis even the ability to run a coffee maker can help getting your life back to normal, which is to say nothing about the fact that a working sump pump can prevent a multi-thousand dollar water damage.
Portable or stand-by generators make a great investment, even if used only a couple of times a year. To make the right investment, you need to determine your house's electrical needs first. Below is a table of power requirements of the most common household devices and appliances that we've compiled from specifications of devices and appliances by various manufacturers. Please note that the numbers in the table are averages and are intended for a rough estimation of the generator power needs. Some appliances may require higher wattage due to their age, capacity, efficiency and additional features. It is best to refer to the user manuals of your own appliances for more precise data. Often times the load data is printed right on the device's nameplate.
Please note that some devices have peak power consumption values that exceed (sometimes by fair amount) the continuous power use values. These are mostly mechanical devices such as pumps and fans/blowers that need extra power to start and speed up. It is best to calculate the generator size based on the peak values, otherwise a large mechanical device like that will create a brown-out condition (voltage lower than normal) which can shut down sensitive loads such as TVs and computers. In some cases this can also be detrimental to the generator itself. Additionally, note that generator run times on full tank of fuel are normally specified at 50% load and the generator itself has both the "running" and the "surge" output values which vary by 30-40%
<table class="table table-striped"> <thead> <tr> <th>Appliance or Device</th> <th>Continuous Watts</th> <th>Peak Watts</th> </tr> </thead> <tr> <td colspan="3"><strong>LOAD ALWAYS CONTINUOUS OR VARIES ONLY SLIGHTLY</strong></td> </tr> <tr><td>Electric Furnace (heat elem.)</td><td>10000</td><td>10000</td></tr> <tr><td>Electric Water Heater</td><td>4000</td><td>4000</td></tr> <tr><td>4-slice Toaster</td><td>1800</td><td>1800</td></tr> <tr><td>Portable Space Heater</td><td>1800</td><td>1800</td></tr> <tr><td>Electric Range (each burner)</td><td>1500</td><td>1500</td></tr> <tr><td>7 cup Electric Kettle</td><td>1500</td><td>1500</td></tr> <tr><td>Roaster Oven</td><td>1200</td><td>1200</td></tr> <tr><td>12 cup Coffee Maker</td><td>900</td><td>900</td></tr> <tr><td>PC with LCD monitor</td><td>400</td><td>400</td></tr> <tr><td>27" LCD TV</td><td>200</td><td>200</td></tr> <tr><td>Portable radio/CD player</td><td>80</td><td>80</td></tr> <tr><td>60W incandescent light bulb</td><td>75</td><td>75</td></tr> <tr><td>Cell Phone Charger</td><td>5</td><td>5</td></tr> <tr> <td colspan="3"><strong>SIGNIFICANT PEAK LOADS</strong></td> </tr> <tr><td>2.5 ton Central AC</td><td>2600</td><td>5000</td></tr> <tr><td>Furnace Fan Blower</td><td>900</td><td>2000</td></tr> <tr><td>Sump Pump</td><td>800</td><td>1500</td></tr> <tr><td>Washing Machine</td><td>800</td><td>2200</td></tr> <tr><td>Microwave Oven</td><td>800</td><td>1000</td></tr> <tr><td>Refrigerator with Freezer</td><td>600</td><td>2200</td></tr> <tr><td>20" Box Fan</td><td>200</td><td>300</td></tr></table>
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Great concept but utterly impractical in the residential environment. Most every generator set for home market is air-cooled. There's no easy (to avoid saying any) way to re-capture that heat. Additionally, you're supposed to position your genset as far back from the house as practically possible, so even more heat will be lost in transfer lines before it reaches anywhere in the house.
Now, what do <strong>you</strong> think about cogeneration?
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