Hot Water Heater Maintenance

Anaheim’s water, as is the case with most of the water delivered throughout Southern California, has a high mineral content. Therefore, homeowners should remember that periodic inspection and maintenance of their hot water heaters is important for keeping the units operating at top efficiency.

Partial draining and/or flushing of the tank will help prevent the buildup of scale and help extend the life of the tank. Draining the tank is a fairly simple procedure that a competent do-it-yourselfer should be able to handle. In fact, several excellent how-to videos on various home maintenance topics are available on YouTube.

However, you may want to consider having an experienced plumber assist you with this project.
Technical drawing of hot water heater with parts labeled
Hot Water Heater Tips
  • Check the temperature and pressure relief valve on your hot water heater annually to be sure the valve is functioning. Consult the operating manual for the procedure. If the valve does not work, have it replaced.
  • Check the temperature gauge on the boiler of your tankless water heater system every 6 months. Consult the operating instructions to determine the correct temperature setting.
  • Check the temperature setting on the hot water heater. If it is above 120°F or 140°F, or if your dishwasher does not have its own heating element, then you are wasting energy and increasing the risk of you or a family member being scalded by hot water.
  • Every 6 months, open the drain valve near the hot water heater tank bottom and drain 1 or 2 gallons of water from the hot water heater into a bucket or through a garden hose to remove any sediment that may have accumulated in the tank bottom Note: If this procedure is not done regularly, residual sediment particles may prevent the drain valve from reseating properly upon closing and the valve washer may have to be replaced.
  • If you have installed an insulation blanket around the tank of your hot water heater, about every 3 months you should check to ensure that the insulation stays in the proper position, noting particularly that it is not blocking the combustion air inlet or the exhaust vent of gas fired units.
  • Important Safety Note: Hot water will drain from the line connected to the relief valve when you open it. Have a bucket handy to catch the water. According to the Uniform Plumbing Code, a pipe should be connected to the pressure relief valve, extending down along the side of the tank to within 6 inches of the floor. This extension pipe prevents the spraying of hot water when the valve is released or if a malfunction occurs.
  • Inspect the exhaust stack on gas fired hot water heaters annually to ensure that all pipe connections are secure and free of rust, corrosion and obstructions. Note: It is essential that fuel fired hot water heaters vent their gasses to the outside; escape of gasses inside the home could be lethal and pose a fire hazard.
How to Flush Your Water Heater
Water heater manufacturers recommend flushing periodically. How often depends upon the quality of the water served to your home or business. Areas with high mineral content, such as we all have here in Anaheim and most of Southern California, should be flushed more often.

Over time, your heater can accumulate sediment consisting of a collection of very fine sand and various mineral deposits. The resulting buildup of sediment can harden, resulting in a variety of interesting noises coming from your tank, reduction of the efficiency of your unit and sometimes even clogging the drain valve.

Steps for Flushing Your Water Heater
  1. Turn off the heater. If your unit is gas, set the gas valve to "pilot" to prevent the burners from coming on while you are flushing it. If your heater is electric be sure to turn off the circuit breakers. If the water level drops below the heating elements and the thermostat turns the elements on, the heating elements will probably burn out quite rapidly.
  2. Connect a garden hose to the drain valve at the bottom of the tank. Make sure the outlet of the hose is in a safe area away from pets and children. It can be very hot can scald quickly
  3. Close the shut-off valve on the cold inlet to the unit.
  4. Carefully open the temperature/pressure relief valve at the top of the tank by lifting the lever. Leave the valve open.
  5. Open the drain valve at the bottom of the heater allowing the water to flow out through the garden hose.
    • If the sediment is clogging the drain valve then try closing the temperature/pressure relief valve and turn the cold inlet valve back on to "power flush" the sediment out.
    • In instances where sediment may have hardened into chunks that can block the drain valve, you may have to run the hot water out of the tank by opening a hot water faucet and let the water flow until it is cool. Then you can remove the garden hose and use a long screwdriver break to break up the clog. This is likely to be a very messy procedure.
  6. When the garden hose runs clear you are finished.
  7. Close the drain valve at the bottom of the tank and remove the garden hose.
  8. Close the pressure relief valve at the top of the tank and turn the cold inlet valve back on.
  9. Open a hot faucet in your house, and let it run until no air comes out.
  10. Turn the heater back on.
How to Flush Your Tankless Water Heater (from Demand Media)
Demonstrations of Procedure Available on YouTube
  1. Turn off the electrical circuit for the water heater at the breaker panel. If the water heater uses a gas heater, rotate the gas cutoff counterclockwise to turn off the gas to the unit.
  2. Remove the cover plate of the water heater unit with a screwdriver to access the unit's wiring. Hold the tip of a non-contact electrical tester against the wiring leading into the terminals. If the tester light turns on, continue turning off breakers or the main circuit breaker to the house until testing all wires shows that no power is accessing the system. Replace the cover plate.
  3. Turn off the water supply valve that feeds cold water to the water heater. Turn off the main hot water valve that sends hot water to the local fixture or multiple fixtures in the house.
  4. Connect one end of a 6-foot garden hose to the outlet of a pond pump or sump pump, then connect the other end of the hose to the cold-water isolation valve. Connect a second garden hose to the hot water isolation valve. Tighten the garden hose couplers with an adjustable wrench.
  5. Place the pump and the open end of the second hose into a 5-gallon bucket. Fill the bucket with 5 gallons of fresh, clean white vinegar.
  6. Open the hot and cold isolation valves on the water heater and turn on the pump in the 5-gallon bucket to circulate the vinegar through the heater.
  7. Let the pump circulate for 45 minutes, then turn off the pump and let the vinegar drain from the water heater through the hoses into the bucket. Close the cold water isolation valve.
  8. Dump the vinegar out of the bucket, then place the open-ended hose back into the bucket. Turn on the cold water supply valve and let the water flow into the bucket for 5 minutes. Close the cold water supply valve and disconnect the garden hoses from the inlet valves.
  9. Turn off the hot water isolation valve. Remove the inlet filter screen per the owner's manual for the water heater and rinse the screen to remove any sediment. Reinstall the screen.
  10. Turn on the hot water supply valve, followed by the cold water supply valve. Open a couple of hot water faucets in the house to bleed any air from the hot water lines. Close the faucets once no more air is in the lines.
  11. Look over the water heater's connections to make sure there are no leaks. Turn on the gas supply valve, if so equipped, and the circuit breaker for the water heater. Test for hot water at the faucets.
Updated November 17, 2014