Electric Water Heater

TPR Valve
Electric water heaters have a TPR valve (Temperature Pressure Relief) or T&P valve, which is a safety device that releases pressure if the pressure or the temperature reach an unsafe level. All tank type units must have a TPR valve, otherwise they could blow up.

There is a manual release lever located on the valve. According to most water heater manufacturers, TPR valves should be periodically tested by lifting the manual release lever at least once a year.

Sometimes the TPR valve is mounted on the top of the tank, and sometimes it is mounted on the side of the tank.

Due to the scalding potential of the discharge from the TPR valve, the outlet from the valve should be piped to a safe area. Typically TPR valve discharges are piped down to within 6 inches of the floor or even outside of the dwelling at near ground level. Check with your local building department for local building code requirements.

View the video to see what happens when the TPR valve fails: Water Heater Blast

Anode
The sacrificial anode is a metal rod usually magnesium or aluminum which helps prevent corrosion of the electric water heaters tank. Electrolysis eats away the anode instead of the tank.

Once the anode is completely gone the tank itself begins to corrode, so you should check your anode and replace it if needed. The anode is screwed into the top of the tank and can in theory be easily replaced. In real life, getting any fitting unscrewed after many years can be quite challenging.

Sometimes the anode is built into a special outlet fitting.

Dip Tube
A dip tube is a long slender plastic tube that drops down into the inlet fitting, usually with a small hole (about 1/" dia.) near the top of the tube.

The dip tube directs incoming cold liquid to the bottom of the tank, preventing pre-mature mixing of incoming cold liquid with the out going hot. If your dip tube is broken, it will seem as though you run out much too quickly.

Thermostat
The thermostat senses when the temperature in the tank drops below a certain set temperature and causes the electric heating elements to come on. When the heater reaches the desired temperature the thermostat shuts off the elements.

Usually the top and bottom elements each have their own thermostat and are wired so that only one element comes on at a time. Normally the upper thermostat comes on first, and then when the top is hot, the upper thermostat re-directs the electricity to the lower thermostat and element.

High limit switch
When the tank gets too hot it trips the high limit switch, (a circuit breaker). The high limit switch is in the top thermostat and usually has a red button. In order to get it working again the high limit switch must be manually reset by pushing in the red button.

Drain Valve
A drain valve allows draining periodically for removal of sediment, or for replacement. In areas with high mineral content it is recommended to drain at least 5 gallons from the drain valve every six months or so to prevent sediment build up. Plastic drain valves are common. Be careful not to break it. I'd recommend replacing it with a brass ball valve. A ball valve has a bigger opening through it making draining sediment clumps much easier.

Water heater problems

Sediment buildup

Water heaters heating of water causes calcium carbonate to precipitate out and settle to the bottom of the tank. Steam bubbles form under the sediment when the burners come on causing popping and other noises.

Regular flushing helps prevent sediment build up.

Not producing enough hot 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

The dip tube is a long slender tube that fits down into the water heaters inlet, and usually has a small hole about 6 inches from the top. 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.

 

Noisy tank

Noise coming from gas models can often be caused by the sediment build up in the bottom of the 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 T&P (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.

T&P valves are strictly an emergency measure and should be replaced every 2 years. At 10 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 T&P Valve.

Water Hammer

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

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 tank to the wall to prevent damage and possible injury during an earthquake.

 

Martin County: (772) 214-9929 Broward/Palm Beach Counties: (954) 340-6615

Email me at: ev@magnuminspections.com

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