No home is complete without a source of hot water. For decades, that system has been basically the same: a water heater comprised of heating elements, a thermostat, and a tank. However, new technology now makes it possible to heat water without using a tank, requiring less space and energy than the old systems. How do these innovative appliances work, and how might you determine which one is best for your home or office?
How Traditional Tank Water Heaters Work
Many homes still have the standard water heater installed. These devices are usually about five feet tall and located in a utility space like a basement. They consist of a tank that typically holds 30 to 50 gallons of water. Inside this tank are heating elements and thermometers that monitor the temperature of the water. Those thermometers are linked to a thermostat, where the homeowner has set a desired temperature for the water. The tank is filled by one pipe and emptied through another pipe, which supplies hot water throughout the house.
As hot water is used at some fixture in the home, the tank begins to empty and is refilled with cool water. This lowers the water temperature in the tank, triggering the thermostat to activate the heating elements and reheat the tank’s contents.
Traditional water heaters may be powered by either electricity or gas, and there is a little difference in how gas water heaters work. However, the basic operation of a tank water heater is the same regardless of the energy source. All tank water heaters store a large amount of hot water that may be under significant pressure, which can be a safety issue as the tank degrades over time.
How Tankless Water Heaters Work
A tankless water heater works on the same basic principle, with one important difference that is clear from the name. The tankless units, also called on-demand water heaters, do not store any hot water. Instead, they utilize heating technology that gets the water up to the desired temperature almost instantly.
As soon as you open a hot tap somewhere in the house, the system detects the influx of cooler water and immediately activates these efficient heating elements. After just a moment needed for the system to “bleed off” the cold water that has already passed the heater, a nearly endless supply of hot water becomes available.
Tankless systems are a fairly recent innovation, so from the first day that Benjamin Franklin Plumbing has been installing tankless systems, they’ve utilized computer technology to optimize performance and efficiency.
A Comparison of The Two Options
There are several advantages to the tankless configuration. The first is energy efficiency. Imagine that your hot water tank is full when everyone goes to bed for the night. The hot water isn’t used until morning, but because the tank gradually cools off even without use, the water temperature may fall low enough to trigger the thermostat and activate the elements. In other words, you’re paying to make hot water that nobody will even use. Additionally, tankless systems use less energy when they do make hot water.
Second, there are some safety concerns with having an aging tank holding 40 or 50 gallons of pressurized hot water inside a home. Many of the required safety features for relieving pressure were not required when older water heaters were installed, so the potential for injuries and damage from a rusty old water heater are real.
Third, tankless systems require far less space than traditional heaters. This creates more flexibility in the design and layout of homes and other buildings. The units are often mounted on a wall in a utility closet, leaving plenty of space for other needs.
Fourth, tankless water heaters have a longer expected lifespan. They have no tank, which means they are not subject to the corrosion concerns that are common with water tanks. Tankless systems also do not have any type of contained pressure. The water does build pressure as it’s heated, but the pressure is discharged through the line to the point of water use. This greatly reduces the strain on the entire unit and all but eliminates any concern of leaks.
Finally, tankless systems never run out of hot water. If everyone in your family showers in a short period of time, or if you run a couple loads of laundry back-to-back, you will quickly find that your hot water supply has run very low. A properly sized tankless system will never fail to meet demand.
The main benefit of a traditional tank water heater is the lower initial cost. They are less expensive to purchase and install than tankless systems, but much of that cost is eventually encountered later through higher utility costs and their expected shorter lifespan.