How to Replace a Shower Mixing Valve

In this video, This Old House plumbing and heating expert Richard Trethewey fixes a faulty valve.

Steps:

1. Use a utility knife to remove the protective cap from the shower-valve handle.

2. Unscrew and remove the handle.

3. Unscrew and remove the plate from the shower wall.

4. Turn the screws on the shut-off valves to the right to stop the flow of water.

5. Remove the cap from the valve by unscrewing the brass screw from each side of the valve. Pull the cap from the valve. 6. Use pliers to pull the pressure-balancing unit from the valve.

7. Flush out debris from the pipes by holding a paper plate under the valve and opening each shut-off valve for just a few seconds.

8. Press the rubber O-rings into the rear of the new pressure-balancing unit.

9. Insert the pressure-balancing unit into the valve, aligning its notch with the key inside the valve.

10. Use plumber’s grease to lubricate the large O-ring on the new shower valve.

11. Insert the new valve into the wall, slip the stainless-steel mounting plate over the valve, then secure both pieces with two brass screws.

12. Open both water shut-off valves with a screwdriver.

13. Screw the sub-base to the stainless-steel mounting plate.

14. Attach the chrome cover plate to the valve by tightening its mounting nut with the chrome sleeve. Then, slide the chrome sleeve over the valve.

15. Next, fasten the handle base to the valve, tightening it with a hex-key wrench.

16. Press the handle onto the stem protruding from the handle base. Be sure to align the handle to the “off” position. Secure the handle with a single screw.

17. Snap the small index cover over the handle screw.