Hot Water Heater Safety


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Your water heater is likely not something you think about on a regular basis, and it's not uncommon to take it's safe operation for granted. But as hard working as your water heater is, it does need maintenance to keep it operating safely and in top form.

Water heaters are frequently installed in out-of-the-way places like a garage, a utility closet, and even in a basement corner, but that doesn't mean that they don't require a little attention. This article will cover water heater safety for a tank-style water heater to help prevent the potential for a serious accident.

Hot Water is HOT!

Your water heater comes from the factory with the temperature already set, but you should check and make adjustments because the factory setting may not be the right setting for you. Many water heaters list the temperature control settings as: Warm; hot; and very hot, which truly isn't very helpful when you're trying to increase or decrease the temperature.

The best way to check your hot water temperature is at the faucet. The temperature should be at least 120° Fahrenheit and no warmer than 130°. You can still be scalded at 130°, but you'll most likely pull your hand away before you're hurt.

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How to Check Your Hot Water Temperature

  • Turn the hot water ON at the faucet nearest the water heater.
  • Allow the hot water to run for 3 minutes.
  • Place a cup under the faucet and fill it with hot water.
  • Insert a thermometer into the cup (a candy or cooking thermometer will work).
  • The temperature should read 120° Fahrenheit.
  • If you adjust your temperature, wait 3 hours before testing again to allow for changes.

Below 120° - There's a risk of exposure to Legionnaire's disease. The Legionella bacteria can grow at temperatures below 120° and you can inhale the bacteria while taking a shower from the mist.

Above 130° - Increases the risk of scalding, as well as wasting energy and sediment build-up in your water heater tank.

How to Adjust Your Water Heaters Temperature

If you need to adjust the temperature, this video will show you how

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Too Hot vs Too Cool: The Temperature Debate

Your water heater's temperature setting is important for health reasons. We all enjoy a hot shower, but having the water too hot can actually be dangerous, and the same is true for too cool.

When the Water's Too Hot

140° Fahrenheit has been the standard for many years and is the default setting for most water heater manufacturers. However, a 3rd-degree burn can occur in adults as 6 seconds at this temperature. A 3rd-degree burn involves all of the layers of the skin, and therefore, is the most dangerous. Young children and the elderly can experience a serious hot water burn in as little as a single second.

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When the Water's Too Cool

The risk of contracting Legionnaires' disease (a severe form of pneumonia that is contracted by inhaling microscopic water droplets - such as from a shower) exists since the risk of colonization in hot water tanks is significant between 104° and 122° Fahrenheit.

According to the Mayo Clinic, it's possible to contract the disease from home plumbing systems, but most outbreaks occur in large buildings. One of the possible causes for this is because the complex plumbing systems within large buildings allow the bacteria to grow and spread more easily.

Hot Water Heater Tanks Can EXPLODE!

If not properly maintained, the quiet appliance that's tucked in a corner, could in fact explode! Each year a few hot water heaters explode, and when they do, they can erupt with enough force to have devastating consequences to your home.

A hot water heater can explode when excessive temperature is combined with tank corrosion. When the water temperature is below 212° degrees, the main concern is scalding. However, if the water temperature exceeds 212°, water turns to steam. 

Steam takes up significantly more space than water (1,700 times more space) which will increase the tank pressure and can create an explosion. Tank-style water heaters are outfitted with an important safety device called the Temperature & Pressure Relief Valve (T&P). It's role is to release pressure within the tank when it builds to an unsafe level.

When the pressure within the tank exeeds a safe limit, a small valve opens and releases water to reduce the pressure. It functions a bit like a tea kettle, only it'll prevent your tank from exploding. The T&P valve needs to be tested annually.

Mythbusters did an experiment a few years ago to see what would happen to a water heater that exceeded the tank's pressure limitations.

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If you have steam instead of hot water coming from your faucet and/or T&P valve is discharging water or steam, SHUT OFF the fuel souce to your hot water heater. For an electric hot water heater, trip the circuit breaker. For a gas heater, shut off the gas valve. Then call a qualified plumber.

  • Never go near the water heater to try to relieve the pressure yourself.
  • Never add cool water to the tank.
  • Never try to cool the tank by spraying it with a hose.
  • Always allow the water heater to cool naturally.

Additional Hot Water Heater Safety Tips

Here are a few additional safety tips to keep in mind when it comes to your gas water heater:

  • Keep the water heater enclosure clean of dust, paper, and other combustibles.
  • Ensure that the pilot light is not lit when using flammable liquids or aerosol bug bombs.
  • If in a garage, the water heater should be raised so that the pilot light is 18" above the floor.
  • Make sure gas water heaters have a good venting system. The vent should be the same diameter as the tank's draft diverter, and it should go straight up and outside (without any dips).
  • If you installed insulating pipe wrap (or any other type of insulation) on a gas water heater, be sure that it's not within 6" of the draft hood or flue exhaust.
  • Although required in earthquake zones, we highly recommend securing your water heater with earthquake straps.
  • An automatic gas shutoff valve is also a worthwhile investment for gas water heaters. These valves will stop the flow of gas if there's an earthquake or a dramatic increase in gas pressure.

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