How To Install A Posi-temp Shower Valve

Installing a Posi-temp shower valve is a plumbing project that, while manageable for experienced DIYers, requires meticulous attention to detail and a solid understanding of plumbing principles. This article provides a step-by-step guide to installing a Posi-temp shower valve. Safety precautions and local plumbing codes should always be considered before beginning the installation.

Preparation and Safety

Before starting any plumbing work, gather all necessary tools and materials. This includes the new Posi-temp valve, pipe cutter or tubing cutter, pipe wrench, adjustable wrench, Teflon tape, pipe joint compound (pipe dope), a level, a measuring tape, a screwdriver set, a soldering torch (if working with copper pipes), and safety glasses. Turning off the water supply to the bathroom at the main shut-off valve is essential. Open the existing faucet to relieve any residual pressure in the lines. Place a bucket beneath the work area to catch any remaining water.

Removing the Old Valve

With the water supply shut off, the old shower valve can be removed. The method for doing so will depend on the type of pipes and fittings used.

Copper Pipe Removal

If the existing pipes are copper, the connections will likely be soldered. Use a pipe cutter to cut the copper pipes a few inches away from the old valve body. Remove any remaining solder from the pipes using a torch and fitting brush to create a clean surface for soldering the new valve. Take care to avoid overheating the pipes, which could damage the surrounding wall structure.

Threaded Pipe Removal

If the existing pipes are threaded, use two pipe wrenches—one to hold the valve body and the other to loosen the pipe connections. Turning the pipes counterclockwise will disconnect them from the valve. Clean the threads of the existing pipes with a wire brush and apply new Teflon tape to ensure a watertight seal.

PEX Pipe Removal

If the existing pipes are PEX, use a PEX pipe cutter to cut the PEX pipes. Use the appropriate PEX fitting removal tool to remove the PEX fittings from the old valve.

After disconnecting all the pipes, detach the old valve from the shower wall. This may involve removing screws or clips. Once the old valve is completely detached, thoroughly clean the area behind the shower wall to prepare for installing the new Posi-temp valve.

Installing the New Posi-temp Valve

The Posi-temp valve should be installed according to the manufacturer’s instructions. These instructions contain critical information specific to the model being installed. Ignoring these instructions could lead to installation errors and leaks.

Positioning the Valve

The Posi-temp valve typically has three ports: one for hot water inlet, one for cold water inlet, and one for the showerhead outlet. Identify each port clearly before making any connections. The hot and cold water inlets are usually marked on the valve body. The valve must be positioned correctly to ensure proper water temperature control and to prevent scalding.

Use a level to ensure the valve is installed horizontally and vertically plumb. This is critical for the shower trim plate to sit flush against the finished wall. Secure the valve to the shower wall framing using mounting brackets or straps provided with the valve. If no mounting hardware is provided, use appropriate screws or fasteners that are compatible with the wall framing material.

Making Pipe Connections

With the valve securely mounted, it is time to connect the water supply lines and the showerhead outlet.

Copper Pipe Connections

If using copper pipes, use flux to clean the outside of the pipe and the inside of the fitting. Slide the copper pipes into the valve fittings. Use a soldering torch to heat the fittings until the solder melts and flows into the joint. Remove the torch and allow the joint to cool naturally. Avoid using excessive solder, which can create drips or weaken the connection. After soldering, inspect each joint for leaks and make any necessary repairs.

Threaded Pipe Connections

If using threaded pipes, apply Teflon tape to the threads of each pipe. Tighten the pipe into the valve fittings using two pipe wrenches. Do not overtighten the connections, which can damage the valve body or the pipe threads. Ensure a tight, leak-proof seal.

PEX Pipe Connections

If using PEX pipes, slide a crimp ring or expansion ring over the end of the PEX pipe. Insert the PEX pipe into the valve fitting. Use a PEX crimping tool or PEX expansion tool to secure the connection. Ensure the crimp ring or expansion ring is properly positioned and tightened according to the tool manufacturer's instructions.

Testing for Leaks

Before closing up the wall, test all connections for leaks. Turn the water supply back on slowly and inspect each joint for any signs of water leakage. If a leak is detected, turn off the water supply immediately and tighten the connection or re-solder the joint. Once all leaks have been resolved, run the shower to test the water temperature and pressure.

Installing the Shower Trim

Once you have confirmed there are no leaks and that the valve is working properly, install the shower trim. The trim typically includes a handle, a escutcheon (the decorative plate that covers the valve), and sometimes a showerhead. Follow the manufacturer's instructions for installing the trim, as different models may have different installation requirements.

First, install the valve cartridge, if it is not already installed. This is the part that controls the water flow and temperature. Then, slide the escutcheon over the valve stem and secure it to the wall. Finally, attach the handle to the valve stem and tighten the set screw.

After the trim is installed, install the showerhead. Use Teflon tape to seal the threads of the shower arm, and then screw the showerhead onto the arm. Tighten the showerhead with a wrench, but be careful not to overtighten it, which could damage the threads.

Final Inspection

After installing the shower trim and showerhead, conduct a final inspection. Turn on the water and check for leaks around the trim and showerhead. Adjust the handle to ensure that the water temperature is comfortable and that the water pressure is adequate. Look to make sure the hot and cold water are not reversed. Make any necessary adjustments before closing up the wall.

Sealing and Finishing

Before finishing the wall, apply a bead of caulk around the escutcheon where it meets the shower wall. This will prevent water from seeping behind the wall and causing damage. Allow the caulk to dry completely before using the shower.

Repair the shower wall and install new tile or other wall covering. This step will vary depending on the type of wall covering and the extent of the damage. Ensure that the wall covering is properly sealed to prevent water damage.

Once the wall is repaired and finished, clean up the work area and dispose of any debris. The new Posi-temp shower valve is now installed and ready for use.

Installing a shower valve is a complex project that might require professional assistance to ensure proper installation and prevent future plumbing issues.