How to Silence Your Noisy Hot Water Heater: Home Clinic

• water
• heating
• homeowners clinic

Q: Our two-year-old gas-fired water heater knocks and rumbles while we use the hot water, and just afterward. Should we buy a new one?

A: Don't give up so easily — this problem is simple to fix. Sediment has built up at the bottom of your tank. When it is heated by the gas burner below, moisture in the gunk flashes into steam that bursts into the water. That's causing the rumbling. Flushing the heater should remove the deposits and quiet things down.

The first step is to turn the heater's gas control to the Pilot setting. Then, shut off the cold-water supply to the heater and attach a hose to the tank's drain valve. Open a hot-water faucet on a nearby sink to prevent a vacuum from forming in the heater, and open the heater's drain valve. The water flowing out of the hose will be murky at first. When it runs clear, shut the valve.

When the job is done, you'll probably find that the water heater's drain valve will not shut completely because it's partially blocked by corrosion and sediment. Be prepared. Buy a hose cap and tighten it onto the valve. If you can't find a cap with an internal gasket, buy Teflon plumbing tape and apply it to the valve threads before tightening the cap.

To refill the heater, open the cold-water supply while leaving the hot-water faucet open. When water flows freely from the faucet, close it and return the gas control to the On setting.

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