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How to troubleshoot & repair a gas or electric tank-style water heater.
Hot water heater problems normally become self-evident: A hot water faucet fails to summon hot water, you see dripping or puddling near the water heater, or the tank emits strange gurgling or popping sounds.
Though many gas utility companies will make a free house call to solve problems with a gas water heater’s burner or the gas supply to the tank, it helps to know how to solve basic outages yourself. (For more difficult issues, contact a qualified local water heater repairperson.)Typical water heater problems include a leaking tank, not enough hot water, water that is too hot, water that is not hot enough, strange noises in the tank, and discolored water. Most problems are easier to diagnose and relatively easy to handle if you understand how water heaters work. See How a Storage Water Heater Works.
Water Heater Does Not Heat Water
The most common complaint with a water heater is that it doesn’t do its basic job. Because a gas water heater operates much differently than an electric water heater, most repairs to malfunctioning water heaters depend on whether the appliances are gas or electric. If you have a water heater that doesn’t properly heat water, see Gas Water Heater Repairs or Electric Water Heater Repairs for specific advice on your type of water heater.
HomeTips Pro Tip: Leaking natural gas can be dangerous. If you smell natural gas (it smells a bit like garlic) near the water heater, shut off the pilot light, close the gas shutoff valve, and call a plumber or your gas utility company for assistance. Always shut off the power to an electric water heater before working on it. Do not work on an electric water heater if there is standing water pooled on the floor near the appliance. Shut off the circuit to the water heater and call a qualified water heater repairperson.
Water Heater Does Not Produce Enough Hot Water
If your water heater suddenly seems to supply less hot water and you’ve made sure it isn’t leaking, flush the water heater tank to be sure mineral deposits are not reducing the heater’s efficiency. To do this:
1) Turn off the water heater’s gas valve or electrical power, depending on whether it is a gas or electric heater.
2) Let the water cool.
3) Turn off the water inlet valve and attach a hose to the drain valve to run the water into a large bucket, to a drain, or to the outdoors.
4) Open the drain valve at the base of the tank, and open one hot water faucet somewhere in the house to let in air. When all water has drained from the water heater, turn the cold water valve on and off until the water from the drain runs clear.
5) Close the drain valve, turn the water back on to fill the tank, and turn the gas valve or electricity back on (relight the pilot if applicable).
This is also a good time to test that the temperature-pressure relief valve, which keeps pressure from building up too much in the boiler, is in proper working order. Lift or lower its handle. Water should drain from the overflow pipe.
If these measures don’t do the job, the dip tube that supplies cold water to the tank may be broken or cracked. This plastic tube is supposed to direct cold water to the bottom of the water heater tank, but, if it breaks or splits, cold water pours in at the top of the tank and mixes with the hot water that is on its way to the hot water pipes.
Either have the dip tube replaced, or, if the water heater is out of warranty and showing other signs of age, consider replacing it.
Water Heater Leaks
Water that drips or pools at the base of a water heater can be caused by any of several issues. See How to Repair Water Heater Leaks for complete coverage of this topic.
Hot Water Is Too Hot
If steam or excessively hot water shoots out of faucets, or you hear boiling sounds inside the hot water heater, the appliance may not be shutting off at its set temperature.
The job of the temperature-pressure (TP) relief valve is to release excessive pressure from steam buildup, but this valve may have been improperly installed, or it may be faulty. Either way, this condition can be dangerous, both because hot water and steam can scald people and because the water heater could rupture.
4) Turn the water heater's temperature back to normal and wait about an hour. If the problem recurs, call awater heater repairperson.
Water Heater Makes Noises
Noises coming from a water heater can be caused by expanding and contracting metal parts; drips; or, more likely, minerals and hard water scale accumulations inside the tank or on an electric water heater’s heating elements. When heated, dissolved hard water minerals recrystallize and form scale that cakes onto interior surfaces of water heaters, making them less efficient and more likely to fail.
To minimize corrosive minerals through ionization, water heaters have a magnesium or aluminum anode rod, inserted through the top of the tank. To avoid scale in the first place, every few months flush out the tank. See “Water Heater Does Not Produce Enough Hot Water” above for complete instructions.
Here are some common water heater sounds you might hear:
Banging, gurgling, or popping. These sounds are caused by the buildup of hard water sediment heating up and exploding inside the tank. You can flush out the tank yourself, although by the time you’re hearing this sound the sediment chunks may be too large to pass through the drain valve. If you have an electric water heater, these sounds could indicate a buildup of scale on your heating elements; it may be time to replace these.
Boiling sound. If water sounds like it is boiling inside the tank, this could indicate overheating and a dangerous pressure buildup. Call a service professional immediately.
Water Is Discolored or Smells Bad
If your water has a strange odor, first determine whether the problem is with the source water or the water heater. If you smell gas near the water heater, shut off the pilot light, close the gas shutoff valve, and call your gas utility company for assistance.
In most cases, an odor is caused by a reaction between the hot water heater’s anode rod and water that has a high concentration of sulfate. Let the hot water run for two or three minutes. If it smells a bit like rotten eggs, the anode rod may need replacement. Call in a plumber.
If the cold water smells, the problem is more likely with your source water.
Iron, copper, and other minerals can cause discoloration in water. If the problem is with both the hot and the cold water, consider installing a whole house water filter and/or water softener. If the problem is only with the hot water, flush the water heater tank as instructed in the “Water Heater Does Not Produce Enough Hot Water“ section above.
General Water Heater Tips
Set the temperature control to about 150 degrees F. or lower if you have no dishwasher or if you have small children or elderly people in the home who might scald themselves.
To minimize the energy it takes to heat the water, insulate your water pipes if they run a long way from your heater to your faucets. Also consider installing a point-of-use water heater.
Periodically check the temperature-pressure relief valve, which keeps pressure in the boiler from building up too much. Lift or lower the lever on this valve. Water should drain from the overflow pipe.
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