I've been able to learn a lot about household water heaters lately. Thanks to the Hawaii Energy Study, we have given over a hundred homes the ability to track their energy. In doing so (and tracking my own use), water heaters tend to be a heavy contributor to overall energy use at home. Don't think you're out of the woods if you have installed solar hot-water heating (I'll save this for another post).
Personally, I've been able to drop my electric bill from $100 to $80 by implementing some simple adjustments to my water heater. That may not seem like a lot, but it's still 20%! Understanding how this appliance works and behaves is key in tweaking your system.
Quick basics: Most electric water heaters have 2 heating elements (which corresponds to the number and location of exterior covers on your tank). The top element is the primary heater. Once the element has reached the temperature you have set, the lower heater will kick on. As you use hot water, cold water replenishes the tank from the bottom up. (see image, courtesy of Popular Mechanics)
First, determine how hot you need your water. This is probably the easiest fix. The health department recommends a typical range of 120F to 140F degrees. Find your comfort level by lowering the temperature on both elements.
TIP: Adjust your cold-to-hot ratio at the tap by lowering your tank temperature along with using less cold water at your faucet. In other words, if you need 50% cold water to even use the hot water, you can get the same end result with cooler hot water and less tap.
Secondly, determine how much hot water you and your family use. If your hot water usage is minimal or spread throughout the day, you can adjust the volume of water that's being heated by your tank. Remember, there's two elements that heat half of the tank at a time. So, if you feel like you won't consume more than half your tank at any given time, you can turn down (or off) the lower element. This will make a bigger impact on your bill, but requires a bit more attention and persistance to find the right settings.
We all know about timers. This is a good way to regulate your water heater's activities and synchronize it with your own. Why would you want hot water when you're sleeping or not at home? When you travel or plan to be away from your home for awhile, make sure your heater is turned off completely.
I also learned that cleaning, or flushing your water heater on an annual basis is a great idea, not only for extending the life of your appliance, but to ensure the crud and gunk build up doesn't affect the heating performance of your unit.
Finally, conservation is always better than efficiency. There's another Kanu article that talks about the health benefits of taking cold showers. I've personally found that hot water is not needed to get dishes clean. You can save energy overall by heating hot water on the stove or in the microwave instead of pulling hot water from your tank. Also, you can cut down the actual flow of hot water being consumed by changing out your fixtures to low-flow and aerated models.
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