What is the tapping sound when my water heat on?

As the water inside your water heater heats up, it expands and causes a slight increase in pressure. This pressure can result in a tapping or knocking sound as the expanding water moves through the pipes. When the water cools down, it contracts and the sound usually goes away.

2. Loose Parts:

The tapping sound could be caused by loose or vibrating components inside the water heater, such as the heating element, thermostat, or pressure relief valve. Over time, these parts can become loose and create a tapping noise as they move or vibrate when the water heater is in operation.

3. Sediment Buildup:

If your water contains a significant amount of sediment or minerals, it can accumulate inside the water heater tank or pipes, causing a tapping or gurgling sound. As water flows through the sediment buildup, it can create turbulence and generate the tapping noise.

4. Water Pressure Issues:

High or fluctuating water pressure can also cause tapping sounds in your water heater. Sudden changes in pressure can cause the pipes to expand or contract, resulting in a tapping noise. This is more likely to occur if your water heater is connected to a municipal water supply that experiences pressure fluctuations.

5. Faulty Thermostat:

A faulty or malfunctioning thermostat can cause the water in the heater to overheat, which can lead to excessive steam production. This steam can create pressure and cause the tapping sound.

If you are concerned about the tapping sound coming from your water heater, it's a good idea to contact a qualified plumber to inspect the unit and determine the exact source of the noise. They can diagnose the problem accurately and recommend appropriate solutions to resolve the issue.