Compare water heater innovations + list of manufacturers |
 Whirlpool site |
Elements
screw into side of tank and come in many shapes and wattages  Check side of tank for wattage <> tank wattage is element wattage |
 |
|
Upper and lower thermostats clip into mountings and read temperature through
tank wall. Reduce temperature and save
3-5%
|
 |
| c | |
| In the past, EnergyGuide numbers on water heaters were large and easy to compare ... |  |
| ... but now, print is small, and estimated yearly cost is much lower than past years. If there were breakthroughs in heating efficiency, why disguise with tiny print? |  |
How electric water heater works:
There is no air inside tank. When hot water faucet is turned on, hot water immediately exits top of tank and travels through pipe until hot water reaches faucet. At same time, new cold water enters bottom of tank through dip tube pipe Read moreHeating is done by electric elements. Tanks have 1 or 2 elements depending on design. Elements are similar to electric stove burners except they have elongated shapes and are designed to be immersed in water. Elements instantly burn out if no water is inside tank. Elements burn out for different reasons and can be replaced. In 2-element tank, if lower element burns out, the amount of hot water is reduced. If upper element burns out, the lower element stops receiving electric signals so neither element works and no hot water is available.
Image shows tank with 2 heating elements called upper and lower elements. Elements are controlled by upper and lower thermostats. Thermostats read temperature through side of tank and turn elements ON and OFF. Residential water heater thermostats can be manually set to temperatures between 90º to 150º. Higher settings use more electricity. Save money by turning down thermostats see how. For each 10º reduction, save 3-5% operating cost. See 9+ ways to save with water heater.
Both elements are never ON at same time unless specific wiring is changed. See how thermostats work. Upper thermostat is main controller. It turns on upper element until top 2/3 of tank reaches temperature setting. After that, upper thermostat turns-off upper element and sends power to lower thermostat which turns on lower element. Lower element runs until tank reaches temperature setting. Also See how to troubleshoot electric water heater.
During 'standby' between hot water use, lower element maintains tank temperature. Lower element keeps water hot by turning-on 3-4 minutes each hour throughout day and night which equals 100Kwh - 200Kwh each month for standby operation depending on tank wattage and seasonal temperature. Once hot water is used again, cold water quickly fills tank and heat cycle repeats..
During 'standby' between hot water use, lower element maintains tank temperature. Lower element keeps water hot by turning-on 3-4 minutes each hour throughout day and night which equals 126Kwh - 216Kwh each month for standby operation depending on tank rating and seasonal temperature. Once hot water is used again, cold water quickly fills tank and elements are activated and heat cycle repeats. Lower element is key factor in 'standby loss.' Water heater manufactures have targeted both elements for wasting electricity. They added electronics to upper thermostat that control initial heating, set lower thermostat 10º less than upper thermostat, and added better insulation to top pipes.
Why is the yearly cost-estimate so low on water heaters compared with past years?
Manufactures have added 2" foam insulation to many products. And some models have heat traps to stop heat from traveling upwards through the pipes. Some tanks are 'self-cleaning' to avoid loss of efficiency. Manufacturers have turned down thermostats on all models from 135º to 120º, or lower. They have re-evaluated the amount of hot water consumed by families. These changes plus reducing consumption always save money. And over whole year, the differences add up to a few dollars per month. But it still takes same number of Kilowatthours (Kwh) to heat a pound of water. The physics hasn't changed. And every pound of hot water that leaves the tank is replaced by cold water that is heated and kept heated until next time hot is used. See water heating math
If great strides were made in electrical efficiency, it would spark a scientific revolution and somebody would be shouting. Instead EnergyGuide numbers that estimate yearly cost have become small and hard to see. The numbers seem amazingly low compared with past years. In defense of manufacturers, they make a safe product that is priced right and they are helping consumers by adjusting their product. You can add your own improvement by installing a timer and scheduling hot water use. 9 ways to save with a water heater