We all need hot water heaters in our homes, so if you’re building one, sooner or later, you’ll find yourself choosing a hot water heater.
There are various types of hot water heaters, and different ways they are powered—by electricity, gas, oil, or solar energy. However, they all share one thing in common: the ability to heat cold water supplied by your local authority or municipality, so you can enjoy hot water on demand when you shower, bathe, or wash clothes or dishes.
While some water heaters don’t have tanks to store water, most do.
Tank Water Heaters
Tank water heaters store water in a tank and heat the water within it. There are various types (or models) that use a full range of heating sources—electricity, gas, oil, and solar power.
Generally, tank water heaters work by drawing hot water from the top of the tank while cold water refills from the bottom. When the heater is turned on, the water is continually heated. Of course, we are all much more aware of the need for energy efficiency nowadays, so we don’t leave our water heaters on all the time. More people are realizing that some water heaters are more energy-efficient than others.
Typically, an energy-efficient storage tank water heater will feature at least one of these:
- Insulation that prevents heat loss through the external walls of the tank (building the tank into a covered space and adding insulation material around it also helps),
- A superior heat exchanger capable of transferring more heat from the energy source to the water,
- Factory-installed heat traps that prevent hot water from flowing out of the tank when not needed but allow water to flow into the tank.
Additional design features that make gas-fired storage tank water heaters more energy-efficient include:
- Electronic ignition instead of an old-fashioned pilot light that stays on continuously, using energy (albeit little),
- A powered exhaust system,
- A mechanism that controls and reduces heat loss through the flue vent,
- Condensing heat exchangers, which are much more efficient than other types.
New technology in oil-fired water heaters also includes high-tech burners that improve energy efficiency.
Uniongas manufactures natural gas tank water heaters with three different venting options:
- Direct vents, which don’t require a chimney,
- Power vents, which don’t need a chimney but use an electrically powered fan,
- Conventional vents, which require a chimney.
Solar water heaters also use tanks, but the water may be heated in a collector, or a special liquid in the collector may transfer heat to the tank. Because weather conditions affect the efficiency of solar water heaters in heating water, they are often paired with an electric element that kicks in when necessary—especially in winter.
Instant Water Heaters
Instant water heaters don’t have tanks and only heat water when it is needed. They are typically small appliances installed to provide instant hot water from a sink or basin that isn’t connected to a regular tank water heater.
The most basic type of instant water heater uses either an electric element or a gas burner. Low-mass water heaters use more advanced technology and are capable of supplying more hot water than traditional instant water heaters. These are usually gas-fired and feature both electronic ignition and a powered exhaust system. They can be connected to an external storage tank if needed.
Stiebel Eltron from GO Tankless (www.gotankless.com) is a popular brand of electric tankless water heaters in North America. Their main claim to fame is advanced flow control technology, which automatically adjusts the water flow rate.
Uniongas also manufactures natural gas tankless water heaters.
Energy-Efficient Water Heaters
When selecting a hot water heater, it makes sense to choose one that is energy-efficient.
In Canada, the efficiency of electric tank water heaters is measured by what is called either “standby loss” or “rating watts loss.” While low standby loss models are clearly the most energy-efficient, it’s also important to choose a heater that meets the needs of your family. If you select one that is larger than necessary (in terms of water volume), it will result in unnecessary energy costs.
Be aware that an energy-efficient electric water heater will typically cost more than one with lower efficiency, but the quality will be better, and you’ll benefit from improved warranties.
The efficiency of gas, propane, and oil-fired water heaters is measured by an “energy factor.” High energy factors indicate the most efficient models, whether tank or tankless. When selecting a gas tank water heater, be mindful that oversized tanks can also lead to inefficiency.
Rheem (www.rheem.com) manufactures a wide range of water heaters, including instant electric or “point-of-use” models, heat pump water heaters, and both gas tank and tankless water heaters for homes.
The US Bradford White Corporation (www.bradfordwhite.com) offers a comprehensive selection of products, including natural and propane-fired gas water heaters, oil-fired water heaters, electric water heaters, indirect water heaters, and solar water systems. Laars Heating System Company (www.laars.com) manufactures gas-fired boilers and volume water heaters. The company is a wholly owned subsidiary of Bradford White.
A.O. Smith Corporation (www.hotwater.com), headquartered in Wisconsin, designs and manufactures two brands of hot water heaters—GSW and John Wood (www.gsw-wh.com). GSW offers both gas and electric models, while John Wood, which is only available to installers, specializes in energy efficiency and offers ENERGY STAR-rated products.
In many countries, tax rebates and other incentives encourage people to install solar and other energy-efficient hot water heaters.
In British Columbia and Ontario, homeowners are eligible for tax-free government grants when they install gas or solar water heaters, or an electric heat pump water heater.
