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 Wednesday, May 23, 2018
Q & A Categories » Cleaning

Water Heaters


I heard you mention using Draino drain cleaner on your radio program for cleaning water heaters. I didn't get the formula written down and would like to have it so that I can clean mine.



We did mention the use of Draino for the purpose of dissolving mineral salts that build up at the base of most water heaters. However, we are informed by a professor of chemistry at Stanford that this could be dangerous if proper precautions are not taken. Before we relate our findings we'd like to share his letter:

"I am writing with regard to some advise broadcast on your radio program involving removing mineral salts from a hot water heater that involved adding a whole can of Draino drain cleaner to the water heater.

Draino is lye (sodium hydroxide) plus aluminum metal chips. In the presence of water these chemicals react to create hydrogen gas. The gas evolution is the reason that Draino makes a boiling sound when used in a drain. It is possible that a whole can of Draino would be enough to form an explosive mixture with the oxygen of the air in the partially empty heater tank. A spark could initiate a terrible explosion. Please warn your listeners of this."

Professor Richard E., Stanford

We really appreciate your input, and know that our readers will too.

One of the countries foremost authorities on water heater maintenance, Larry Weingarten, whose research in water heater maintenance and energy efficiency is currently being studied by PG&E, has been testing various dilution's of the Draino for us at his lab in Monterey. Larry has gotten fantastic results, but agrees that we should go to pure lye as found in Red Devil drain cleaner (no aluminum) instead of the Draino.

Larry recommends one cup of Red Devil drain cleaner to three or four gallons of water, and here's how he recommends that we do the job:

  1. Turn off the gas and drain the water heater.

  2. Remove the cathodic anode (the hex nut at the top of the heater). This provides an opening at the top of the tank and allows you to check the anode all at the same time. The anode should be about 5 feet long and about 1/2" in diameter and should not look deteriorated. If it is replace it (about $9.00).

  3. Pour in one cup of Red Devil crystals (don't premix with water the lye in solution is highly caustic and very dangerous).

  4. Add 3 to 4 gallons of cold water to the tank and let it sit for about 3 hours.

  5. After 3 hours has passed add a quart of vinegar (any kind) to the tank and turn the water supply on again.

  6. When the tank is about 1/3 full begin draining the solution out of the tank.

  7. Fill and flush the tank two more times adding a quart of vinegar at the beginning of each filling (the vinegar will help to neutralize the lye and clean it from the tank).

Weingarten tells us that a clean water heater means a minimum of 5% savings in water heating costs, cleaner hot water, less noise and no rotten egg smell.

You may not realize it, but if you have never cleaned your tank the mineral salts we refer to probably exist in your water heater.

See more Q&A in the Cleaning category!

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