You probably don’t spend a whole lot of time thinking about your water heater, and that’s a good thing. As long as it’s producing hot water there’s really not much you need to do. But, you should have at least a basic understanding of how the system works and what options you have when the heater needs replacing.
There four basic types of residential water heaters: tank-type, hybrid, tank-less, and point-of-use. Tank-type heaters are by far the most popular kind but tank-less water heaters are growing exponentially each year. Hybrid models are relatively new, but worth considering if you’re seeking maximum energy efficiency. And point-of-use heaters are ideal for quickly delivering hot water to faucets and appliances located far from the home’s main water heater.
A vast majority of homes have conventional tank-type water heaters, which are powered by either gas or electricity. Generally speaking, gas water heaters are more expensive to buy than electric models, but cost less to operate because gas is cheaper than electricity. However, electric water heaters are more efficient than gas models and have higher energy-factor ratings.
Tank-type water heaters come in various sizes, ranging from about 20 to 80 gallons, but a 40- or 50-gallon tank is sufficient for most households. If you’re shopping for a gas water heater, consider a condensing unit. It operates at higher efficiency by capturing hot exhaust gases before they exit the flue and redirecting them through a coil at the base of the unit. The incoming cold water then absorbs much of the heat from the gases.
The downside of tank-type water heaters is that they hold a limited supply of hot water and may struggle to supply enough hot water during high-demand periods. Also, tank-type heaters burn energy (gas or electricity) day and night to maintain the water temperature, regardless of whether or not anyone’s using hot water, a phenomenon known as standby heat loss.
As its name implies, a tank-type heater has a large insulated storage tank that holds hot water until it’s needed. Here’s how it works: Cold water enters the bottom of the tank and is heated by either a gas flame below the tank or electric elements suspended inside the tank. An adjustable thermostat regulates and maintains the water temperature. A pressure-relief valve prevents an excessive buildup of pressure inside the tank.
When hot water is called for at a faucet or appliance, heated water is pumped out the top of the tank and through the home’s hot-water supply pipes. As the water level drops in the tank, it’s automatically refilled with cold water, and the whole process starts over again.