Should I Turn Off My Water Heater When It’s Not in Use?

2018 Apr 09
Posted in: Plumbing

Many homeowners ask us if they should turn off their water heater between uses to save money.

Our professional answer after crunching the numbers? No, unless you’re going on vacation for a month or longer, you shouldn’t turn off your water heater.

Here’s why:

  1. You won’t see significant energy savings
  2. You’ll create more problems by turning your water heater off/on repeatedly

Instead, if you’re going on a short vacation (less than a month) we suggest just turning your water heater thermostat down or to “vacation” mode.

We’ll explain all of our above points (and throw in some extra energy-saving tips) below…

Two reasons not to turn your water heater off

1. You won’t see significant savings

After some calculations, we determined that the average Phoenix homeowner will only save:

  • Approximately $0.76 per day by shutting off their gas water heater
  • Approximately $1.36 per day by shutting off their electric water heater

Note: To calculate the numbers above, we used Energy.gov’s water heater energy cost calculator. We plugged in Phoenix’s average electric/gas rates and assumed a 60-gallon gas water heater with an EF of .67/60-gallon electric water heater with an EF of .92. Your specific savings may vary depending on your hot water usage, water heater EF and your local utility rates.

That said, unless you’re looking at a month-long (or longer) vacation, the accumulated savings won’t be worth dealing with some of the problems you may encounter by turning your water heater on/off.

Which brings us to our second point...

2. You’ll just create more problems

When you turn your water heater off between uses and back on within a short period of time, you’ll deal with the following issues:

  • No hot water when you return. When you get back from your trip, you’ll be greeted by a tank full of lukewarm water—which makes for a nasty surprise when you jump in the shower. Depending on your water heater, you may have to wait anywhere from 20 minutes to over an hour for hot water.
  • Difficulties turning unit back on. Just like Murphy’s Law warns, anything that can go wrong, will. We’ve had several homeowners call us when they can’t get their water heater to turn back on after shutting it completely off for several days. Homeowners with older units are especially at risk of experiencing problems. That’s because old units may go through a higher-than-normal amount of stress when turned back on and forced to heat an entire tank of cold water. This extra stress may result in needed repairs.

Instead of turning off your water heater, do this...

If you’re going on vacation, turn your water heater thermostat down or to “vacation” mode.

By turning the thermostat down or to “vacation” (an option on some newer models), you can lower the amount of electricity/gas that your model will consume while you’re gone. Most newer water heater models have this vacation option, usually labeled as “VAC” on the thermostat.

Typically, the “VAC” mode will reduce the water temperature to 50° F so that your water heater doesn’t work as hard as it does in normal operation (when it’s constantly keeping water heated to 120-130°F). But this mode also keeps the water relatively warm so that your unit doesn’t overwork itself when you turn the unit back on.

Don’t see this “VAC” option? Then just lower the output temperature on your water heater thermostat to anywhere from 50–70°. This will achieve the same results as the vacation mode.

Other ways to lower your water heating costs

Interested in other ways to lower your utility bills? Then consider the following water heater energy-saving tips:

  • Insulate your tank to save 7% to 16% annually. If your water heater is warm to the touch, it means you’re losing money as we speak. You see, older water heaters lose a lot of their heat via the tank itself (which is why it feels warm), this is called “standby heat loss”. To lower your standby heat loss, have a professional insulate your tank.
  • Get your unit regularly flushed/maintained. A water heater in Arizona should be flushed at least once a year. “Flushing” a water heater means draining it completely, removing any sediment buildup and then filling it back up. Sediment buildup occurs frequently in Arizona because we have “hard” water (water with a lot of minerals in it). Those minerals eventually settle to the bottom of your water heater and insulate the burners from the water, making your water heater work harder and longer than it should.
  • Lower the output temperature to save 4% to 22% annually. Reducing your water heater temperature cuts down on the gas/electricity that your unit needs to keep the water heated. Note: Don’t go lower than 120°F as lower temperatures than this can increase the risk of Legionnaires Disease.

Have more water heater questions? Ask an Arizona plumber

Whether you need a water heater repair, replacement or tips, we can help.

Just contact us for 24/7 service and professional certified plumbers who are happy to help.

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