Water Heater Flushing

[cougartrace]

I have a gas water heater.

I've heard that it is not necessary to shut gas off to flush a tank. You would just attach a water house to flush valve and turn on and let it clear out while water and gas still on?

What do you think?

[LazyPup]

Most of the new water heaters have a sealed burner and push button ignition system so relighting the pilot is not a problem, but for some of the older tanks where you have to depress the gas valve while manually lighting the pilot, turning the gas off can be a real hassle.

If you have the older style manual pilot you may not want to turn the gas off, but it would be best to turn the thermostat down to low while flushing the tank.

If you discover you have to perform some maintenance on the tank that would require draining it, then you must turn the gas off.

For those who have electric water heaters it is a good practice to turn the breaker off before performing any maintenance or service on the tank.

When flushing a water heater many people make the mistake of turning the water heater cold water supply valve off and draining the tank by gravity. That will not effect a good flush of the tank. The preferred mathod is to leave the water supply valve open, attach a hose to the drain cock and open the drain cock to get a good power flush from the water pressure.

A word of caution here. Most water heaters come with a cheap plastic drain cock. In many cases once that valve has been opened they do not reset well, which results in a minor leak.

I prefer to remove the plastic valves and replace them with a brass boiler cock, which is a full bore valve that will last the lifetime of the tank.

Most water heaters have a 3/4" NPT thread mount and you can buy a 3/4" brass boiler cock valve at any local hardware or home supply center for about $5.

To replace the valve, turn the gas off, close the cold water supply line and drain the tank.

Unscrew and remove the existing valve.

Apply a bit of pipe dope to the threads of the new valve and screw it in tight, then open the cold water line and open a hot water faucett to bleed the air our of the tank as the tank refills.

Once you have a full steady flow of water at the faucett, close the faucett and relight the gas pilot.