Water heaters: hot tips for a better buy.(CR Home)

You probably don't think much about your water heater until a cold shower or a telltale puddle suggests that you need a new one--now. How to choose? Most look alike on the outside. But a look inside tells a very different story.

Sawing open 18 gas and electric models confirmed that paying a little more for a longer warranty typically buys you a better water heater. Several smart steps can also help you save money, avoid installation hassles, and get enough hot water, even on busy mornings.

See whether it's fixable. While a corroded, leaking tank isn't salvageable, a leaky drain valve or pressure-relief valve or a worn-out electric heating element can be repaired. But replacing the heater may make more sense.

Find out by getting a repair estimate. Then weigh that amount against the $500 to $600 you'll pay for a new heater with installation. A rule of thumb: Consider a repair if the labor cost, which warranties often exclude, averages less than $50 per year for each remaining year of coverage. Otherwise put the roughly $100 you'll pay just for the plumber's visit toward installing a new unit, especially if yours is out of warranty

Look past capacity. Most water heaters are sold on that basis. But a water heater's first-hour rating (FHR) is more important, since it tells you how much hot water the heater can deliver in an hour of use.

Determine how much hot water you need based on the busiest hour of an average day Figure on roughly 2 gallons for shaving, 4 gallons for washing face and hands, 5 gallons for preparing food, 10 gallons for a dishwasher, and 20 gallons each for a 10-minute shower and a load of laundry Factor in growing children and other issues that can increase your water needs.

Once you've arrived at a total, be sure that the FHR on the new heater's yellow EnergyGuide label meets or exceeds that amount.