How to Check the Mixing Valve on a Tub

Checking Temperatures

• 1

  Look at the mixing valve, focusing on the hot and cold indicators. Hot water should be indicated on the left, cold water should be on the right. If they're reversed, the valve was installed upside down.

• 2

  Turn on the water in the tub. Turn the mixing valve to the right and let it run for 10 to 15 seconds. Test the water with your hand; it should be cold.

• 3

  Turn the mixing valve to the left. After the water runs for another 20 seconds, carefully test the temperature with your hand. The water should be hot. If you don’t get hot water from the tap, try the hot water in the bathroom sink. If there is hot water there, but not in the tub, then the mixing valve may need replacement.

Checking for Leaks

• 4

  Towel dry the tile around the mixing valve, as well as all the tile leading down to the tub.

• 5

  Turn on the water in the tub. Let it run for 20 seconds, then turn the mixing valve to hot. Wait another 20 seconds and turn it to cold. Examine the tile around and below the mixing valve for water. If you see water dripping down, that indicates a leak from the valve itself.

• 6

  Turn off the water. Tap the tiles around the mixing valve with the handle of the screwdriver. Listen for any that sound hollow when you tap them; this indicates a leak causing damage behind the tile.