MAINTENANCE : When Good Water Heaters Go Bad

Water heaters have rela tively few components and are fairly easy to service. But when problems do arise, the heaters can send out confusing signals.

Because trouble can strike any part of your hot-water system, it helps to think in terms of its three basic elements: the heat source, the tank and the pipes, including all faucets and hot-water appliances.

Piping systems cause some problems often blamed on the water heater. High operating costs may be traced to a dripping faucet or leaking pipe.

A faucet that drips only one drop per second wastes nearly 800 gallons of hot water per year. In such a case, a simple, inexpensive water faucet repair will pay for itself many times over.

Long, uninsulated pipe-runs also waste hot water. When you draw water from a faucet at the end of such a run, hot water must displace water that cooled in the pipe; to get a quart of hot water, you must draw several gallons from the tank. Keep the heat from dissipating so quickly by insulating all hot-water pipes.

Hot-water storage tank problems can call for a simple parts replacement or a whole new tank. An aging water system may carry sediment into the tank, or sediment may collect as flakes of calcium and lime.

In electric models, sediment-covered heating elements will burn out quickly. In gas heaters, sediment accumulates in the bottom of the tank and forms a barrier between the heat source and the water. Steam bubbles percolate through the sediment and cause a continuous rumbling sound.

So, if your electric heater burns up lower elements frequently, or if your gas heater rumbles, sediment may be the culprit.

To remove sediment, drain as much water as possible from the tank. Next, with the draincock still open, turn the water on full pressure to flush the tank. Reduce the pressure by half and, finally, shut off the water and allow the tank to drain completely.

A fallen dip tube is a relatively uncommon problem that can bypass unheated water to the outlet pipe. The dip tube is a pipe that delivers incoming cold water to the heat source near the tank bottom.

If it slips through the cold water inlet fitting and falls into the tank, cold water entering the tank is drawn through the hot-water outlet without being heated.

To replace a dip tube, disconnect the inlet pipe from the tank. Then, cut a length of half-inch-diameter soft copper tubing long enough to reach within 12 inches of the tank bottom. Flare the pipe end so it’s slightly larger than the inside diameter of the inlet fitting. Insert the tube into the fitting and reconnect the inlet pipe. You can leave the old tube in the tank without problems.

Late-model water heaters have a magnesium rod to coat voids in the porcelain tank lining. An anode sacrifices itself to prevent rust and prolong the tank’s life.

These rods seldom cause problems, but when they do, it’s often a chemical reaction to acids and minerals that gives the water a gassy odor or taste. To correct this, unscrew the magnesium rod and replace it with an aluminum rod. Most retail plumbing outlets stock them.

A relief valve keeps the heater from exploding if the thermostat sticks. When pressure builds and the water gets too hot, the relief valve opens. However, the valve spring can weaken and release water unnecessarily. To correct this, simply remove the old valve and screw in a new one.