As a typical American husband, I know a thing or two about hot water since I'm often in it.   For example, I've learned that there are different home water-heating systems to choose from.  However, when your conventional tank water heater fails, the easier and more affordable option is usually to replace it with another tank water heater.  But how do you choose one that fits your house, budget and eco-conscience?

The main considerations are:

Energy Factor - This is the heater's overall energy efficiency rating.  It is based on the ratio of hot water produced to fuel used on a typical day.  Take a look at the heater's EnergyGuide Label to see how efficient the unit is.  Also, consider heaters that are Energy Star qualified.  In addition to passing rigorous efficiency testing, Energy Star products are often eligible for rebates.

•    Eco-tip: Look for an insulation value of R-24 or higher.  If your electric heater isn't well insulated (touch the tank; if it's warm, you need more insulation) you can add an insulating blanket to prevent heat loss.  For a gas heater, call a pro and have them install the blanket.  Improper installation can be a fire hazard.  Blankets are inexpensive and available at most hardware stores.

Recovery time (first hour rating) - This is part of the Energy Factor.  It is the number of gallons the heater can raise 90 degrees Fahrenheit in one hour.  Look for it in the upper-left corner of the appliance's EnergyGuide Label.  Remember: A short recovery time means using a lot of energy to quickly heat water.  Don't buy a tank that puts out more than you will need, or you're just wasting energy and money.

Gas vs. electric - Natural gas heaters have higher first-hour ratings than electric ones with the same capacity tank, but are typically less energy-efficient.  However, electricity normally costs more than natural gas.  Check to see what you have now.  Do you have a natural gas valve near your water heater or an outlet?  Since both types have very efficient options, I'd recommend sticking with what you had.

Capacity - How much hot water do you need?  The best rule of thumb I've found is to count your bathrooms. 1 to 1 ½ bathrooms = 40-gallon tank.  2 to 3 ½ bathroom house = 50-gallon gas-heated tank or a 66- to 80-gallon electric-heated tank.  Another good tool for picking the right capacity is to determine your peak hour demand.

•    Eco-tip: Simple conservation can make a big difference.  Washing machines can use 18 to 40 gallons per load.  The average shower head uses about 2 to 2.5 gallons per minute. By washing your clothes in cold or warm water (they get just as clean!) and taking a shower in 10 minutes instead of 15, you can greatly reduce the amount of hot water you use.

Your water heater should last about 10 years, so take your time and do your homework.  The bottom-line:  The cheapest to buy is the most expensive to run and will waste the most energy.  If you're able to spend a little more up front, you'll make the money back in savings and help protect our planet, too.