How hot water heaters work, common problems with water heaters, and how to repair, fix, and maintain a water heater complete with diagrams

Gas Water Heaters - A Detailed Look At How They Work Including TP Valves, Pilot Lights, Flues, Gas Burners, Thermostats,  Sediment Buildup, Anode Rods, Dip Tubes and More.

Water heaters - Water heater problems, maintenance, and repair.
 

Sediment buildup

The heating of water in your water heater causes calcium carbonate to precipitate out and settle to the bottom of the tank. Also contributing to sediment buildup are any particulates that may be in your water supply like sand. Sediment is usually more of a problem in areas with very hard water.

Sediment buildup depends upon what kind of water you have.  In some areas there is virtually no sediment and in other areas sediment buildup can be significant. Regular flushing of your hot water heater helps prevent sediment build up. More about sediment
 

The water heater runs out quickly, or only produces warm water

Check for a broken dip tube, wrong setting on a thermostat, a defective thermostat, burned out heating elements (electric), or a heavy build up of sediment.
 

Dip tube problems

The dip tube is a plastic pipe that fits down into the water heater inlet, and usually has a small hole about 6 inches from the top of the pipe. The dip tube directs the incoming cold liquid down to the bottom of the tank.  If the dip tube is broken, the incoming cold liquid can mix with the out going hot liquid and cause it to seem as though you are running out. The small hole is t prevent the dip tube from collapsing if for some reason the water must leave the heater through the inlet. More about Dip Tubes
 

Noise coming from the water heater tank

Noise coming from gas models can often be caused by the sediment build up in the bottom of the water heater tank. Steam bubbles form under the sediment. The thumping and popping noises are created by the bubbles escaping from under the sediment. 

Sizzling noises can be caused by condensation dripping onto the hot burner.
 

Thermal expansion

When water is heated it expands. If the inlet is not blocked by a check valve, pressure reducing valve, or other device, the increase in volume simply travels back into the source. If the inlet is blocked, this increase in volume will cause an increase in pressure, sometimes to dangerous levels.

The TPR (Temperature-pressure) valve relieves this pressure by discharging some liquid. A thermal expansion tank can be installed in the line that will absorb the increase in volume, preventing the relief valve from discharging unnecessarily.

TP valves are strictly an emergency measure and should be replaced every 2 years.  At 180 degrees , the temperature that the T&P valve opens, damage can occur to your system and you may have voided the warranty on your water heater.

The improper installation of backflow preventers can block the thermal expansion leading to operation of the TPR Valve.
 

Water Hammer

When water is traveling in the pipes it has kinetic energy (energy of motion).  When a valve shuts off suddenly a shock wave results.

Water hammer most often occurs when a valve shuts off suddenly.  Commercial arrestors are available to combat this problem.  They consist of a small air bladder within a cylinder plumbed to the piping system near the valve causing the problem. Some hardware stores carry them.

Sometimes if the piping is sagging then supporting the pipe solves the problem.
 

Milky color

Water contains dissolved oxygen and other gases. When it's heated it has less ability to hold these gases and when the pressure is lowered  as the liquid comes out of the tap these gasses can form tiny bubbles giving the liquid a milky appearance.  Letting it stand for a few minutes will allow these bubbles to rise out of the liquid and it resumes its clear appearance. If you live in an earthquake prone area then be sure to strap the water heater tank to the wall to prevent damage and possible injury during an earthquake.