Everything You Need To Know About Your Home's Water Heater
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.
Here are brief explanations of how each type works:
Tank-Type Water Heaters
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.
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.
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.
Hybrid Water Heaters
A hybrid water heater is a tank-type heater that’s equipped with an electric heat pump. The pump is mounted on top of the water-storage tank and it uses a compact compressor and evaporator coil to capture heat from the room air and then transfer it to the incoming cold water. As a result, a hybrid model uses 60% less energy than a conventional water heater.
Now, you do have to pay a premium for such high efficiency: A hybrid water heater costs nearly twice as much as a standard water heater, but most families recoup that added expense within three to four years through lower electric bills. And state and local energy rebates can shorten the recoup time even more.
Tank-Less Water Heaters
Tank-less water heaters are compact, wall-hung units that provide hot water for the entire house—not just single faucet—and are often called instantaneous or on-demand water heaters. And as you may have guessed, this type of water heater has no bulky storage tank.
Here’s how it works: A tank-less water heater sits idle until a hot-water tap is opened in the house. Then, cold water is drawn into the unit and a flow sensor activates an electric heating element or gas-fired burner, which warms an internal heat exchanger. As the cold water passes over the heat exchanger it’s warmed to the preset temperature. Hot water then exits the heater and travels directly to the faucet or appliance—not to a storage tank. Combustion gases, produced by gas-fired units, are exhausted through a dedicated, sealed vent pipe.
When the hot-water tap is turned off, the heater shuts down, and therein lies the main benefit of tank-less water heaters: Since there’s no storage tank to keep filled, tank-less models only heat water when it’s called for. As a result, a tank-less water heater delivering 40 gallons of hot water per day uses about 34% less energy than a standard water heater.
And for even greater energy efficiency, consider a condensing tank-less water heater, which operate with an efficiency rating between 90% and 98%; non-condensing tank-less units operate at a still-impressive 80% or so.
And because there’s no storage tank, tank-less water heaters provide an unlimited supply of hot water, which is a real bonus for large families. And tank-less heaters last up to 20 years, nearly twice as long as standard tank-type water heaters. On the downside, tank-less water heaters do cost more to purchase and install than standard water heaters, and they’re often more costly to repair.
Point-of-Use Water Heaters
Unlike the previously mentioned whole-house water heaters, point-of-use water heaters are compact, tank-less models that deliver hot water almost instantaneously to one specific location, such as a bathroom sink or shower.
This type of electric heater is most often installed at fixtures located far from the main water heater. Its biggest selling point is that it eliminates the all-to-common annoyance of opening the tap and then waiting for hot water. Such an inconvenience wastes not only time, but an immense amount of water and energy, too.
Most point-of-use units measure only about 10 in. x 13 in., so they easily fit inside of vanity cabinets and closets, and feature simple plug-in installation. Point-of-use water heaters are extremely reliable and can easily last up to 25 years. And since there’s no standby heat loss with point-of-use water heaters, all the energy consumed is delivered at the tap. Of course if there’s not a GFCI electrical outlet nearby to plug in the unit, you’ll have to hire an electrician to install one.
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