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Hot water tanks (or heaters)

Canadians use an average of 75 litres of hot water per person per day, but where does all that hot water come from? Most homes heat water in a tank, usually hidden in the basement or laundry room.

In this article, we’ll teach you everything you need to know about your hot water tank.

What is a hot water tank?

A hot water tank (also known as a hot water heater) is exactly what it sounds- a large tank designed to hold and heat water for various household requirements. There are several types of hot water tank, the biggest difference being the method of heating. Propane gas is still the most popular, but electricity, oil and solar powered tanks are also available.

Most tanks hold around 200 litres of water. Depending on the size and type of tank you choose, prices range from a few hundred to a few thousand dollars. Tanks with higher thermal efficiency tend to be more expensive, but could save you money in the long run.

How do hot water tanks work?

A hot water tank is essentially quite a simple device; a tub of water connected to your plumbing containing a heating element. The tank is made of metal with a protective liner inside to prevent corrosion. There is then a layer of insulation to prevent heat loss, and finally the outside layer to hold it all together. Combustion style heaters (oil or gas) require some kind of exhaust vent to expel the burnt air, much the same as a car does. Older models might even require access to a chimney.

Cold water enters the tank near the top, then makes its way via a cold-water intake tube to the bottom where it is heated by a burner or element until it reaches the temperature determined by the thermostat. The hot water rises to the top of the tank, where it exits and is sent to the rest of the home.

Most manufactures recommend setting your thermostat no higher than 49°C, though BC Hydro recommends at least 55°C to prevent the formation of bacteria. One solution to both problems is to install a mixing valve. This ‘tempered’ water will be directed to your sinks, showers, and any other location that water comes into contact with skin. The water sent to your washing machine and dishwasher can bypass this valve and will come out at a higher temperature. This will allow you to reduce the risk of both bacteria and scalding- especially important for those with young children in the home.

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

Here are some of the most common issues with hot water tanks and what you can do to address them.

  • No hot water: The most common cause for gas fired tanks is the pilot light. This is a small flame that burns constantly and serves as an ignition source for the main burner. If the pilot light goes out, your burner won’t be able to heat the water in your tank. Relighting the pilot is actually pretty simple- check out this Home Steady video for instructions. (Note: if you have a closed burner system or if you can’t see the pilot light, it’s best to call a professional.) Another possibility is a damaged or disconnected dip tube (which sends the cold water to the bottom of the tank). This causes cold water to mix with hot, lowering the overall temperature.

  • Not enough hot water: If your hot water runs out prematurely, your heater may simply be too small. Natural Resources Canada has a chart to help you determine what hot water tank size is right for your home.

  • The tank is leaking:This can be a symptom of a serious problem that will usually require professional help. If you notice water around your tank, first shut off the fuel source and then the cold-water supply. Reliance Home Plumbing and City Wide Water Heater Service both have videos showing you how to do this.

  • 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 (hence the hissing sound), but this doesn’t mean the tank’s not leaking. Get a professional to take a look.

  • There’s a boiling sound coming from the tank: This could indicate overheating or a pressure build up. Call a plumber immediately.

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What can you do to maintain your hot water heater?

While most tanks should last around ten years, some simple maintenance can easily extend this lifespan and save you money in the long run.

  • Flushing the tank: This should be done annually to remove built-up sediment. When sediment accumulates, your hot water heater may make popping or knocking sounds. This is caused by water bubbling through the sediment. Check out this video for an in-depth guide to flushing your tank, or see Lowe’s guide to water heater maintenance.

  • Checking and replacing the sacrificial anode: Hot water tanks contain a sacrificial anode, usually made of magnesium or aluminum. This strip of metal attracts corrosive minerals in the water to prevent them harming the tank itself. Once fully corroded, the anode is no longer effective and must be replaced. Experts recommend doing this every 1-3 years, though homes with hard water may need to do this more often. Replacing the anode is a simple procedure- check out this video by

  • Relieving the pressure: Setting the thermostat high can result in increased water pressure. Hot water tanks have a release valve called the temperature and pressure release valve (T&P). This should be checked periodically to make sure it’s functioning correctly. In extreme cases, explosion can occur, so be sure to keep the thermostat set within recommended limits.

What is the life expectancy of a hot water tank?

The average life expectancy of a residential hot water tank ranges from 6 to 10 years. If you’re not sure of the age of your tank, check the serial number. For most brands, the first four digits indicate the month and year of manufacture. If your tank is nearing the end of its life, the following signs could mean it’s time to find a replacement:

  • Water is leaking from the tank.

  • 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.

  • You notice corrosion marks: Check the nipples where the hot-water exit pipe meets the cold-water intake pipe. This is a prime location for corrosion.

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?

In the unfortunate event that your hot water tank ruptures, take the following action to prevent further damage to your home:

  • Shut off the water: There’s usually a valve on the cold-water line close to your hot water tank. Close this as soon as possible. If you can’t find it, use your home’s main water shut-off valve which is usually in the basement of a house or the bathroom of a condo. (It’s a good idea to locate this valve before you need to use it.)

  • Shut the power off: Electric water tanks have heating elements which are designed to be submerged in water. When the element is exposed only to air it can present a fire hazard. Locate the breaker for the hot water tank on your circuit breaker board and flip the switch to OFF. If the tank is heated by gas, you’ll need to shut off the main gas valve.

  • Contact your home insurance provider: Home insurance policies usually cover water damage that results from a ruptured tank. However, exclusions are specific to each policy, so check your coverage with your provider. Be sure not to throw anything out until you’ve spoken to your adjuster, as they may need to see the damaged items if you decide to submit a claim.

If you’re concerned about the risk of water damage in your home, check out Square One’s Preventing Water Damage article.

How to replace your hot water tank

If your hot water tank needs replacing, the first step is to decide what type of system you want to replace it with. Is now a good time to go tankless? Tankless systems only heat water when it’s required. As a result, they offer energy (and cost) savings, plus the luxury of unlimited hot water. They also take up less space and often have longer life spans than hot water tanks. On the downside, they’re more expensive to purchase and smaller units may not be appropriate for those with significant simultaneous hot water demands.

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.

If changing like for like, here’s a quick warning: If your hot water heater is located in a tight spot, we recommend hiring a plumber. Regulations on insulation have resulted in increased diameters for a given capacity of tank, potentially requiring complex re-routing of your water and gas pipes.

For those comfortable taking on the task themselves, installation will depend on which type of tank you choose:

Gas tanks

  1. Turn off the water and gas supply lines.
  2. Detach the chimney cap and open a hot faucet to allow air into the system, then drain the tank into a bucket or sink from the T&P valve.
  3. Disconnect the inlet and outlet water pipes (you may need to cut them to do this) and remove the water tank. We recommend having at least two people for this job.
  4. When reinstalling the new tank, allow at least six inches of space for ventilation. Reconnect the water supply line to the tank using a dielectric fitting, then reconnect the gas line.
  5. Turn both lines back on and check for leaks by covering the connection in liquid soap and looking for bubbles.
  6. Set the thermostat and then light the pilot.
  7. Turn the control knob on and you should hear the burner ignite. If it doesn’t, you may need to relight the pilot.

Electric tanks

  1. Start by turning off the electricity supply at the circuit breaker.
  2. Remove the junction box (contains electrical wiring; usually located on the top of your tank) and disconnect the wires.
  3. Open a hot faucet until the water runs cool, then shut off the cold-water supply to your tank and connect a garden hose to the T&P drain valve. Open the valve and empty the tank into buckets or a drain.
  4. Once the tank is empty, remove the discharge pipe from the T&P valve- you may have to cut the pipe- and disconnect the water supply lines before removing the old tank.
  5. Set the new tank in a drain pan and install the pipe on the T&P valve to direct the water towards a drain if possible. (If not, you can use a bucket.)
  6. Attach the inlet and outlet water hoses to the pipes using dielectric fittings.
  7. Remove the aerator from a hot faucet and open the tap.
  8. Turn on the cold-water supply and check for leaks using liquid soap at the connections and checking for bubbles. Your tank will now start filling with water. Once water runs from the faucet, the tank is full, but allow it to run for 3-5 minutes to ensure all air is out of the tank.
  9. Reconnect the green ground wire, then the remaining wires according to the manufacturer’s guidelines. Finally, turn the power back on and set the thermostat.

IMPORTANT: Don’t do this until the tank is completely full, or you could run into an issue known as ‘dry firing’, which could damage the heating element in your tank, or even cause a fire.

Heating the water may take several hours, but if you see any water dripping from the tank, consider lowering the pressure. Plumbers recommend 80 PSI or less.

What will your home insurance company want to know?

Home insurance providers may ask about the age of your hot water tank when you fill out your initial application. Once a tank passes its normal life expectancy, the risk of leaks or corrosion is increased. Insurers may advise (or in some cases require) replacement before coverage is issued. In other cases, replacing your hot water heater may reduce your premium.

If you have any other questions about hot water tanks, feel free to contact Square One at 1.855.331.6933 for more information.

Hot water tanks (or heaters)

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