Getting to know hot water tanks (or heaters)

We all love a nice hot shower. But where does that hot water come from? If you live in a house, you’ve probably noticed a big metal cylindrical tank located somewhere out of the way, probably in the basement or maybe the laundry room.

What is a hot water tank?

A hot water tank (also known as a hot water heater) is basically a big tank filled with water. It has a heating mechanism located inside the tank, powered by gas, electricity, solar power, or oil. The tank is made of metal, with a protective liner to prevent it from corroding. There is then a layer of insulation, and finally, the outside layer to hold it all together.

A typical tank holds 180 to 225 liters of water. Natural Resources Canada has a chart to help you determine what hot water tank size is right for your home. Depending on the type you choose, hot water tank prices can range from a couple hundred dollars to a couple thousand. If you want to purchase a high-efficiency tank, you can expect to pay a higher price compared to the standard electric or gas tank.

How do hot water tanks work?

Cold water enters the tank near the top and then makes its way via a cold water intake tube to the bottom of the tank to be heated. You should notice a shut-off valve just outside and above the unit, which controls the flow of water into the tank. You also may see a drain valve, near the bottom of the tank. This allows the tank to be drained for various reasons: to move the tank to a different spot, to remove any built up sediment, or to replace the elements inside the tank.

The water is heated by a burner or element until it reaches the desired temperature. As we all know, heat rises, so the hot water rises to the top of the tank, near the pipe which carries it to the rest of the house. There is a thermostat so you can control the temperature of the hot water. It usually can be set between 49 and 60 degrees Celsius. BC Hydro recommends setting the tank to no lower than 55 degrees to prevent bacteria forming in the tank. If you have small children in the house, it’s best to set it towards the lower end to prevent scalding.

There seems to be quite a controversy over water temperature. Some say it should be no less than 60 degrees in the tank in order to kill harmful bacteria, but should be closer to 49 degrees at the faucet. Of course, you should always turn on the cold water first, and then slowly add the hot. But, another way to reduce the risk of scalding is to install a mixing valve, which adds some cold water to the hot, after it comes out of the tank. This “tempered” water will be directed to your sinks, showers, and any other place where water is used to bathe. Water to your washing machine and dishwasher can bypass this valve, to come out at the higher temperature. Another option is to install anti-scald devices at individual taps.

What should you do when your hot water tank is not working?

Listed below are common issues and tips on how to address them.

  • No hot water: You’re not getting any hot water? There could be several reasons for this. Maybe the unit is too small to keep up with the hot water demands in your house. Or it could be that the dip tube, which sends the cold water to the bottom of the tank, could be damaged, causing cold water to mix with the hot in the tank, lowering the overall temperature. The most likely reason, if you have a gas tank, is that your pilot light has gone out. Now what? Actually, relighting the pilot light is pretty simple. EHow has a video that clearly demonstrates the steps. The Family Handyman also explains how you can relight a pilot light, and if that still doesn’t work, you may need a new thermocouple. But they warn that if you have a closed burner system, or can’t see a pilot light, call a professional. explains how to troubleshoot a gas powered tank.
  • The tank is leaking: Yikes. You really don’t want this to happen. If you notice water around your tank, the first thing you need to do is shut off the fuel source, either gas or electrical. Next, shut off the cold water supply. Reliance Home Plumbing and City Wide Water Heater Service both have videos showing you how to shut off the fuel supply, and turn off the water.
  • There’s a hissing noise coming from the tank: This could mean that the liner inside the tank has corroded or cracked, and water is leaking. You may not see any water on the ground, as the leaking water is boiling and turning to steam (thus the hissing sound), but this doesn’t mean the tank’s not leaking. Get a professional to take a look.

If you’re not a really handy person, you should consider calling a professional when something goes wrong. They’ll advise you on whether you should repair or replace your hot water tank. You may save some money working on the tank yourself, but it may not be worth the risk of scalding yourself, flooding your house, or creating a dangerous gas leak and possibly an explosion and fire.

What can you do to maintain your hot water heater?

Most tanks have a life expectancy of approximately ten years. But there are things you can do to extend its life. These are fairly simple maintenance procedures that, whether you do them yourself or you hire a professional, can save you a lot of money.

  • Flushing the tank: This should be done annually to remove built-up sediment from the bottom of the tank. has a video on how to drain your tank to remove sediment that may have built up in the bottom of the tank. Family Handyman has a resource on flushing an electric heating tank. Lowe’s has some step by step tips for how to maintain your hot water tank. You can tell that sediment has built up if your heater starts making a popping or knocking sound. This is caused by water beneath the sediment trying to bubble up through the sediment.
  • Checking and replacing the sacrificial anode: Hot water tanks contain a “sacrificial anode,” usually made of magnesium or zinc. This type of metal will corrode more quickly than the metal in the tank. When you have water heating in a tank, something’s going to corrode. This magnesium or zinc anode basically sacrifices itself to protect the tank. Once it’s fully corroded, the water will begin to corrode the tank itself. Some experts recommend replacing the anode every few years to extend the life of your water heater. and This Old House both have great videos on replacing the sacrificial anode.
  • Relieving the pressure: Pressure can build up in the tank, especially if you have the heat set too high. Hot water tanks have a release valve, called the “Temperature and pressure relief valve” or “T&P.” This should be checked regularly to make sure it’s actually working. If it gives out, pressure can build up in the tank until it actually explodes! Keep the temperature set at the recommended limit. Any higher can cause excess pressure, not to mention possible scalding. Hiring a professional for an annual inspection can save you a lot of worry. Canadian Residential Inspection Services Ltd. has more information on exploding hot water tanks.

What is the life expectancy of a hot water tank?

The average life expectancy of a domestic hot water tank generally ranges from 6 to 10 years. If you’re not sure the age of your tank, you may be able to find out by checking the serial number. The first four digits indicate the month and year.

Tanks will suffer corrosion over time, and can start to leak, or even rupture. Various things can affect how quickly your tank will corrode, such as how hard or soft your water is, and how high the temperature is set (the hotter the water, the more quickly it will corrode). What should you look for to see if it’s time to replace the tank?

  • Water is leaking from the tank: This is the most common way people discover the tank needs replacing.
  • Water is not as hot as it should be: There could be corrosion on the heating mechanism, making it necessary for you to keep turning up the thermostat to get enough hot water.
  • Water aerators in your faucets are clogging: The water aerators are small screens that screw on the end of your faucets to give the water a nice smooth flow. If you take them off, and notice bits of plastic stuck in the screen, they could be coming from the water heater. The cold water intake tube is usually made of plastic and could be deteriorating.
  • Reduced pressure when you turn on the hot water.
  • Corrosion marks: You may start to see corrosion marks around the outside of the upper rim a/o the lower rim, or around the “nipples,” where the hot water exit pipe and the cold water intake pipe meet the tank.

BC Hydro offers some tips to make your water heater more efficient or just to cut your water heating costs:

  • Use less water.
  • Insulate your hot water pipes.
  • If your tank is warm to the touch, you’re losing heat. You can buy an insulating blanket, but even though it seems simple to install, get a professional. If a blanket is put on a gas fired heater incorrectly, it could be hazardous.
  • Reduce your water temperature to 55 to 60 degrees C. Keeping the heat no higher than 60 degrees will also help slow corrosion. Don’t go below 55ºC, or you risk developing harmful bacteria in your water system.

What should I do if the hot water tank ruptures?

You might discover that your hot water tank has ruptured when you step into a cold shower, or perhaps when you walk into a big flood in the basement. Here’s what you should do:

  • Shut off the water. There will be a water supply pipe on the heater itself, usually right at the top, where the water enters the tank from the main water line. Or you can just find your home’s main water shut-off valve. This is a good reminder to find outwhere your water shut off valve is if you don’t already know.
  • Shut the power off. Hot water tanks all have heating elements which are designed to be submerged in water. If they continue to heat, with no water around them, you could be looking at a fire, in addition to a flood! You should be able to locate the breaker for the hot water tank on your circuit breaker board. If the tank is heated by gas, you’ll also need to shut off the gas. It may be wise to get out of your house until any built up gas dissipates.
  • Contact your insurer. Generally speaking, home insurance policies cover the resultant water damage after a water tank ruptures. There are always exclusions and deductibles, so check with your agent to find out the type of coverage you have. You shouldn’t throw away anything until you’ve spoken to your adjuster. He may need to see the damaged items.

Of course, there are many things you can do to prevent water damage in your home, including the proper way to store valuable items in your basement. Check out Preventing Water Damage.

What will your home insurance company want to know?

If you’ve recently purchased home insurance, you may have been asked about the age of your hot water tank. Once a tank has passed its life expectancy, the odds are pretty good that it will corrode or leak sooner or later. You may find that insurance companies will advise you to replace your hot water tank in order to keep your rates low, or they may even decline to insure your house until the tank is replaced. A leaking or ruptured tank can cause significant water damage to a home.

It’s in everybody’s best interest to keep your hot water tank in tip-top shape, and to consider replacing it when it begins to show signs of wear. If you have any other questions, you can always contact Square One at 1.855.331.6933 for more information.

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