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Economizing water heater efficiency

Q: Our 12-year-old water heater does not always provide enough hot water in the morning. Does it make economic sense to get a new, high-efficiency model? What designs last the longest before leaking? - Ann K.

A: It can make excellent economic sense to replace an old electric water heater with a larger (first hour rating), more efficient model. This can provide plenty of hot water in the morning and still lower your electric bills substantially.

High-output new long-life electric water heaters

There are several new electric water heater designs that have lifetime, never-leak warranties. These never-leak models, in particular the newer 100 percent plastic ones, are also the most efficient electric water heaters made. No matter what your water conditions are, you will never replace the water heater tank again.

Electric water heaters are rated by their efficiency factors (EF). By comparing EFs, you can determine the savings. With electric water heaters, the amount of tank insulation and its internal design affect the EF the most. Heat trap fittings also help.

For a typical family of four, replacing an old electric water heater at an EF of 0.80 with a new model at an EF of 0.95 yields savings of about $80 per year.

Even if you replace your old water heater with a new one of the same tank size, you will have more hot water for morning showers because the high levels of tank insulation reduce heat loss. Some models also have optional high-output 5,500-watt heating elements. Check the maximum capacity of your wiring before using these elements.

Some of the best new models have so much insulation that the hot water in the tank loses only one-third of a degree per hour even if the power goes off. These models typically use earth-friendly non-CFC (no ozone layer damage) foam insulation.

The proper way to size your new water heater is by its first hour rating (gallons of hot water available in one hour). This includes the gallons of hot water in the tank plus the amount of water the elements can heat in one hour. Check with your water heater dealer for a hot water usage chart to estimate your family's peak hot water requirements in the morning.

Most electric water heaters that have a lifetime, never-leak warranty, use all-plastic water tanks and outer shells. Other electric water heaters use a glass-lined steel tank that has a limited life. The newest, super-efficient plastic design (Marathon) looks somewhat like a large inverted test tube.

This design, with a domed top, is ideal for efficiency and high hot water output. Since the hottest water naturally moves to the top of the tank, the spherical shaped top provides room for extra insulation. The bottom of the tank is also spherical for complete drainage and more complete sediment removal.

The inner tank, is made of safe polybutylene plastic wrapped with fiberglass reinforcement for superior strength. It cannot leak. If you have ever noticed a foul smell to your hot water, the anode rod reacting with natural chemicals in your water often causes it. Plastic water heaters need no anode rod because they don't rust.

Another unique long-life design, the Hydrastone layer, uses a one-half-inch thick stone lining inside the steel tank instead of glass. This layer blocks corrosive oxygen in the water from reaching the steel tank.

If your area has hard water, consider several design features. Choose a design with a large hand-size opening at the lower element, to remove severe sediment deposits. Look for names like "Hyrdajet" or "Jetforce," which have special water inlet tube designs to create turbulence and minimize sediment deposits. Some models also use built-in magnetic "limefighters" that help to keep the sediment suspended.

Write for (or instantly download - the Utility Bills Update No. 495 - buyer's guide of the 11 most efficient and never-leak electric water heaters, EFs, outputs, warranties, features, first-hour rating worksheet and an operating cost/payback chart. Please include $3 and a business-size SAE. Mail to: Jim Dulley, Illinois Country Living, P.O. Box 3787, Springfield, IL 62708.

James Dulley is a mechanical engineer who writes on a wide variety of energy and utility topics. His column appears in a large number of daily newspapers.

Copyright 1998 James Dulley


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