A hot water heater drain or flush is one of the most important, and often times overlooked, maintenance procedures. Periodically draining or flushing the storage tank removes harmful minerals and sediments that if unchecked, will compromise the energy efficiency, performance and life expectancy of the entire system.
Most manufacturers and water heating professionals recommend draining about a quart, or up to a gallon, of water every three to five months. In regions with hard water, storage tank sediment build up is likely to occur even quicker, so in these regions a hot water heater drain or flush should be more frequently performed.
Please be advised that when servicing a water heater there's always the risk of scalding, and scalding is a serious health hazard even for healthy adults.
It's always a good idea to have additional towels and/or rags available when performing water heater maintenance tasks.
If you're uncomfortable or uncertain about performing such tasks on your own, there's no shame in consulting with a local water heating professional. After all it's always better to be safe than sorry.
The water heater drain valve is located near the bottom of the tank. Before draining, it's always wise to reference the manufacturers' owners manual.
Open the water heater drain valve and allow a reasonable amount of hot water to drain from the tank. A good rule of thumb is to drain the hot water until it is relatively clear and sediment free.
The water flowing from the drain valve initially may be dark, rusty or even sandy, this is perfectly normal.
Some water heater manufacturers and industry professionals recommend annually flushing the entire storage tank.
Remember to periodically flush or drain the tank in the future, again this hot water heater maintenance task is essential.
When flushing the entire storage tank, both the power supply as well as the water supply must be turned off. The hot water tap should also be left on while flushing the storage tank. This assists with the flushing process as well as the removal of unwanted air within the tank and plumbing pipes.
The hot water tap should be closed when all the water from the tank is flushed. The power supply can be turned back on only when the water supply has been reopened and the tank is refilled.
Most water heater drain valves can be fitted to a standard garden hose, which can be ran to a sink (or outdoors) to assist with the flushing process.
How to flush or drain a hot water heater with a clogged valve
If the storage tank has not been properly maintained and if you reside in an area that has acidic or hard water, the sediment build up can clog the drain valve. In most cases, the mineral build up has hardened around and even within the water heater drain valve.
Turn of the power supply, if this hasn't been done already. Place a bucket underneath the water heater drain valve or fit a garden hose around it, if this hasn't been done already.
Then close the temperature pressure relief valve and reopen the water supply if previously shut off. In most instances reopening the water supply and closing the temperature pressure relief valve while the water heater drain valve is open is enough to break up the sediment build up.
If after a few minutes the drain valve remains clogged, then shut off the water supply and reopen the temperature pressure relief valve. Carefully use a foreign object, such as a short coiled wire, and attempt to break up the build up around the drain valve.