Gas & Electric Tankless Water Heaters

WHY TANKLESS?

Tankless water heaters, also known as demand-type or instantaneous water heaters, provide hot water only as it is needed. They don’t produce the standby energy losses associated with storage water Tankless Diagramheaters, which can save you money.

HOW THEY WORK

Tankless water heaters heat water directly without the use of a storage tank. When a hot water tap is turned on, cold water travels through a pipe into the unit. Either a gas burner or an electric element heats the water. As a result, tankless water heaters deliver a constant supply of hot water. You don’t need to wait for a storage tank to fill up with enough hot water. However, a tankless water heater’s output could limit the flow rate if poorly chosen.

Typically, tankless water heaters provide hot water at a rate of 2–5 gallons (7.6–15.2 liters) per minute. Gas-fired tankless water heaters produce higher flow rates than electric ones. Sometimes, however, even the largest, gas-fired model cannot supply enough hot water for simultaneous, multiple uses in large households.

For example, taking a shower and running the dishwasher at the same time can stretch a tankless water heater to its limit. To overcome this problem, you can install two or more tankless water heaters, connected in parallel for simultaneous demands of hot water. You can also install separate tankless water heaters for appliances — such as a clothes washer or dishwater — that use a lot of hot water in your home.

  • Advantages

    • For homes that use 41 gallons or less of hot water daily, demand water heaters can be 24%–34% more energy efficient than conventional storage tank water heaters.
    • Can be 8%–14% more energy efficient for homes that use a lot of hot water — around 86 gallons per day.
    • Can achieve even greater energy savings of 27%–50% if  installing a demand water heater at each hot water outlet.
    • ENERGY STAR® estimates that a typical family can save $100 or more per year with an ENERGY STAR qualified tankless water heater.
  • Disadvantages

    • When considering gas tankless heaters, they tend to have higher flow rates than electric ones, yet they can waste energy if they have a constantly burning pilot light. This can sometimes offset the elimination of standby energy losses when compared to a storage water heater.
    • In a gas-fired storage water heater, the pilot light heats the water in the tank so the energy isn’t wasted.
    • The cost of operating a pilot light in a tankless water heater varies from model to model.
    • When purchasing a model that uses a standing pilot light, you can always turn it off when it’s not in use to save energy.
    • Also consider models that have an intermittent ignition device (IID) instead of a standing pilot light. This device resembles the spark ignition device on some gas kitchen ranges and ovens.