How to diagnose water heater woes

Conventional water heaters are simple. Cold water enters the tank and is heated by an electric element or gas burner. A thermostat regulates the temperature, usually 120 to 140 degrees. As the water heats, pressure builds inside the tank. When you turn on a tap, pressure sends hot water out the faucet.

Because water heaters contain few moving parts, only a few things can go wrong.

  • Pilot light on gas water heater flickers out.
  • Circuit breaker for an electric heater trips.
  • Burner or heating element fails.
  • Theromostat breaks.
  • Valve sticks.

Repairing or replacing any of those parts is relatively inexpensive: A plumber can do the job for $150 to $300.

But if the tank is more than 10 years old, or if it’s leaking, a new water tank likely is in your future.

When replacement is your only choice

Over time, water minerals react with steel, corroding water heater tanks. When water heaters spring a leak, repair isn’t an option.

On the bright side, modern water heaters are far more energy-efficient than older models. Manufacturers now inject foam insulation between the tank and its outer shell, resulting in higher heat retention. New glass liners make tanks less prone to corrosion.

You’ll pay $500 to $1,500 to purchase and install a new conventional storage unit. A high-efficiency model that meets Energy Star standards saves up to 20% in energy costs.

Tankless, heat pump, and solar water heaters offer even bigger savings and also qualify forfederal tax credits. Some credits expire at the end of 2011 but others run to 2016.  These products cost three to five times more to buy and install, so consider payback carefully.

Factor in hidden costs of water heaters

Even with conventional water heaters, replacement might not be as simple as hauling out the old and hooking up the new. Many local building codes now require you to upgrade the following:

  • Water heater mount
  • Size or type of venting system
  • Drain pan underneath the heater
  • Supply pipes

Before starting work, ask your installer to outline all costs.

If you know your way around plumbing tasks, you may be able to install the new unit yourself. Most manufacturers provide detailed instructions, and you’ll need to check your local building codes. Turn off the water and gas or electric before you begin, and take particular care to vent gas models properly.

Maintain your water heater

Whether you repair or replace, water heaters will perform better and last longer if you flush the tank once a year to remove sediment. A bonus: Without all that gunk inside, your water heater will operate more efficiently, saving you money.

Also, check the anode rod — sometimes called the sacrificial rod — every three years. An aluminum or magnesium probe inside the tank, it collects corrosive elements and should be replaced when caked or eaten away. A new one costs about $30.

Stay on top of these simple maintenance tasks and you can avoid thinking about water heaters again for a long time.