Most Canadian homes heated with natural gas also use gas for their domestic hot water supply.
An efficient way to heat your water
Hot water heaters are the second-largest energy user after space heating. Depending on the number and type of people in your household, hot water consumption may account for more than 20 per cent of your total annual energy consumption.
The energy factor
The efficiency of water heaters is measured as an energy factor (EF): the amount of energy supplied as hot water, divided by the total amount of energy used by the water heater over a 24-hour period. The higher this number, the more efficient the heater. The EF can be increased with better insulation and refined design.
The higher the EF, the better it is for the environment, and your wallet. To determine the EF for a particular water heater, read the manufacturer's manual or speak to your retailer.
Gas water heaters are covered by federal and provincial efficiency standards. Find out more.
Buying a water heater
When contemplating which type of water heater to purchase, consider your household needs and your budget.
Regardless of which type of water heater you choose, you'll want to carefully compare products, particularly their installation and repair warranties. A contractor will take the time to understand your needs before providing a quote on a model.
Remember to consider the cost of adding a gas line and appliance exhaust venting if your home is not already fitted for natural gas appliances.
Calculating efficiency and cost
Actual day-to-day costs for heating water depend on your use, efficiency and the cost of fuel. To get the most value, figure out the cost of use for several models and compare them to the purchase price. The lowest purchase price may seem like a good deal, but it might cost more in the long run.
The efficiency of water heaters is measured as an "energy factor" (EF), or the amount of energy supplied as hot water divided by the amount of energy used by the water heater over a 24-hour period. The higher this number, the more efficient the heater.
Perfect energy conversion (where all energy becomes hot water) would be an EF of 1.0. A new, mid-sized natural gas water heater (189 litres/50 gallons) has an EF of .61. On-demand systems are typically rated between .81 and .85, about 40 per cent more efficient than storage tank models.
The higher the efficiency of your water heating system, the more you will save on energy costs. For example, if you replace a 40-50 gallon storage tank water heater with an EF of .58 to a high-efficiency tankless water heater with an EF of .80, you can reduce your fuel costs.