How does a tankless water heater work?

Are you considering installing a tankless water heater and would like to know how one works before you tankless water heater gutsdo? Let’s take a look at the design and functioning of today’s tankless water heaters that offer continuous and cost-effective hot water to any point in your home. Make sure to read 7 Things to Know Before You Buy.

1. They heat water directly without the use of a storage tank, as you already know, so that water is heated only when it is needed, the key to cost savings on energy. Cold water flows into the unit, is heated and dispersed for use. The water is heated through the use of an electric element or, in gas-powered tankless water heaters, by using natural gas or propane. When you look inside even a compact tankless unit you’ll usually see more than a foot of pipe, sometimes run back and forth, in which the heating takes place.

2. In a whole house system the larger capacity unit is fed by a single cold water line and the hot water is dispersed for use in the home exactly as it would be with a traditional tank-style water heater. The advantages are obvious. First, with a tankless system you’ll never heat a 30-50 gallon tank full of water only have it cool off and require reheating later, a situation often called “stand-by heat loss”. Tankless hot water heaters are energy-misers relative to tradition hot water heaters. Secondly, because the water is instantly heated you can enjoy continuous hot water. There’s no recovery time as there is with a traditional water heater.

3. The capacities of tankless water heaters vary. Those designed to serve an entire home, cabin or condo for example, will produce 6-12 gallons per minute of hot water. Smaller units designed to service single rooms, zones or points of use are capable of making 1.0-6.0 gallons per minute. Sizing the tankless water heater to fit your usage needs is an essential part of selecting the right one.

4. The gallons per minute capability listed with any tankless hot water heater is based upon the ambient temperature of the water entering the unit. For example, if you choose a unit that says it is capable of delivering 5.0 g.p.m. of 110-degree F water when the incoming water is 65, it will have a lower capacity of about 4.0 g.p.m. if the incoming water is only 55F, and about 3.5 g.p.m. if the water is from a deep well at enters at about 50F. It is important to have an idea of the temperature of the incoming water. City water run in cold climates is naturally cooler than in warmer climates, and there are also some differences in well-water, though not as much. In short, a home in a cool or cold climate will requires a higher capacity tankless water heater than would the same size home in a warm or hot climate. As an ancillary note, you’ll use more energy heating water in a cool or cold climate, but the energy usage will still be well below what you’d use with a traditional water heater.

5. Tankless water heaters are used residentially and commercially wherever hot water is needed. Those installed in commercial settings are capable of heating water to a higher temperature for commercial purposes. All tankless water heaters have thermostat controls to prevent accidental burns.

6. Tankless water heaters may even be used outdoors. Models designed for exterior use like the Rheem H95 are ideal for heating the water in a backyard hot tub. They even come with freeze protection so can be used in climates where the temps dip below 32F.

Remember: All tankless water heaters should be installed by a licensed professional. If you decide to DIY make sure to read your warranty as well as your local codes first. Don’t know where to start get free quotes from your area.

Do you have any questions or comments about this article? Post them here and start a discussion. Our goal is to help homeowners find the solutions they need using tankless water heaters wherever they need on-demand, continuous hot water.

Outside Resources:
How Do Tankless Heaters Work?
How Stuff Works

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