Hot Showers For Everyone

By Frank Wagner

June 20, 2008 4 min read


Lower energy bills, no wasted water? Tanks a lot!

By Frank Wagner

Copley News Service

One strategy to lower your hot water bill might be to sing shorter songs in the shower. But a more far-reaching method is to install a tankless water heater.

Units are variously known as tankless, instantaneous or on-demand water heaters and those names sum up what they do - provide immediate hot water without a storage vat. Conventional storage tank heaters keep large quantities of water heated, even if it is not about to be used. Since the units constantly reheat their reservoirs of 40 to 50 or more gallons, they are continually expending energy. Tankless units' heating devices are triggered when a hot water tap is opened. Turning on the water triggers powerful heating elements that heat water rapidly as it passes through the unit.

While the units are relatively new to the American scene, according to, they have been fixtures for 75 years in Europe, Asia and South America where energy costs are much higher.

The startup for a tankless water heater is fairly high. Units cost 2 to 2 1/2 the price of conventional units (online direct prices range from $500 to $1,100 for gas, $200 to $775 for electric), so suggests that a homeowner should shop for one if energy bills are high and tankless water heater looks like a good long-term investment; the current unit regularly fails to provide enough hot water; or if it is broken and cannot be repaired.

Before choosing a unit, you need to determine the size, typically linked to the number of bathrooms you have. As the makers of tankless units love to point out, the heaters can provide an endless supply of hot water. But there are limits as to how much can be produced at any given time. For a house with one bathroom, a heater supplying three to four gallons per minute will do; for two bathrooms, a four- to 5.5-gallon per minute is recommended; for two to three bathrooms, a 5.5 to 7.4 gallon per minute unit is indicated. Also consider if a dishwasher or washing machine will be running at the same time or when someone is showering.

You also need to select your power source. Tankless units can be heated with electricity, natural gas or liquefied petroleum gas. If you have sufficient power (120 or 240 volts and 50 to 200 amps, depending on the unit), electrical models are much easier to install than their LP and natural gas counterparts which require venting and combustion air. But electricity tends to cost significantly more than gas in the long run and gas heaters have a higher hot water output than electric models - a must if you're using a lot of hot water at one time.

A demand water heater can be installed centrally or at the point of use. Large gas units, which can supply an entire house, are installed centrally. An electric configuration can make use of a small booster unit for a remote bathroom or laundry.

Tankless water heaters - even the largest whole-house models - take up little space and can be placed in a closet.

Even with the high startup, there is an eventual payback both in water and energy saving. Hot water bills can be trimmed 11 percent to 69 percent, according to A U.S. Department of Energy study estimated that water heating counts for 20 percent or more of an average household's energy expenditures. In a typical U.S. household, more than 9,000 gallons of water are wasted waiting for the water to heat.

And to save even more, you can still sing shorter songs.

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