How To Install a Pressure Balance Shower Valve

Installing a pressure balance shower valve can help homeowners prevent sudden temperature changes in their showers and avoid potential scalding. This makes showers safer and more comfortable, and the installation process can be a snap for do-it-yourself enthusiasts. Read how to install a pressure balance shower valve in less than 2 hours below, and watch the video above for plumbing tips from This Old House’s Richard Trethewey.

Understanding Pressure Balance Shower Valves

Pressure balance shower valves keep water at a consistent temperature even when fluctuations occur elsewhere in your home’s plumbing system. These valves automatically adjust the mix of hot and cold water to compensate for sudden changes in water pressure.

Inside the valve body, a stainless steel balancing piston does the heavy lifting. Its shoulders move across the hot- and cold-water inlet and outlet ports, increasing or decreasing the water supply to maintain a stable temperature. The valve also includes a stop spindle that shuts off the water supply for easy maintenance — a critical feature that allows you to service the cartridge without turning off water to the entire house.

How Pressure Balance Valves Work

A pressure balance valve contains an internal mechanism that responds to changes in water pressure. When the cold water pressure drops because of a flushing toilet, for example, the valve automatically reduces the hot water flow by the same amount. This keeps the shower temperature stable, and prevents unexpected bursts of hot water that can cause scalding.

Benefits of Installing a Pressure Balance Valve

Installing a pressure balance affords you the advantages below.

• Compliance with modern plumbing codes in many areas
• Consistent shower temperature
• Enhanced comfort during showering
• Improved safety 
• Potential water savings by reducing the need to readjust the temperature

Preparing for Pressure Balance Shower Valve Installation

You’ll need to gather the tools and materials you need for installation before you begin the project. 

Tools and Materials Needed

You’ll need the tools and materials below to install a pressure balance shower valve: 

• Adjustable wrench
• Cold chisel (1/2-inch)
• Copper pipe and fittings
• Drill/driver with 3/16-inch masonry bit
• Flux and solder
• Hammer
• Level (2-foot)
• Pliers
• Pressure balance shower valve kit
• Propane torch
• Reciprocating saw with metal-cutting blade
• Teflon tape
• Tubing cutter

Pro Tip: Richard Trethewey, This Old House plumbing and heating expert, advises: “The cardinal rule before starting any plumbing project: Turn off the water.” He also recommends never using a hacksaw to cut tubing, as it may leave the tube’s end rough or crooked and unsuitable for soldering. Use a tubing cutter instead, and take it slow on the first revolution to make sure the cutting wheel stays in its groove.

Don’t be daunted by the many tools listed. As noted in This Old House Magazine, several are included just in case: You can’t know exactly what you’ll need until you can see inside the wall. Consider keeping a small “imp” tubing cutter on hand for working in tight spaces, along with a fireproof plumber’s cloth to protect surrounding surfaces when soldering. You should also have a bucket of water and/or a small fire extinguisher nearby as a safety precaution, plus emery cloth for cleaning copper fittings before soldering.

Pro Tip: Richard Trethewey also warns that when soldering an angle stop, make sure it’s open: “If it’s not, the torch will heat up the air in the tube and cause it to pop right off.” Additionally, always thread nuts by hand before tightening with a wrench or pliers — copper and brass are soft metals, so it’s easy to cross or strip threads and ruin fittings.

Installing the New Pressure Balance Valve

Once you remove the old valve, you can begin installation. You must take precise measurements and solder carefully to achieve proper fit and function. 

1. Turn off the water that leads to the bathroom. Use pliers and a manual handle puller to remove the faucet handles and escutcheons from the hot- and cold-water faucets.
2. Unthread the faucet stems from the shower wall using an adjustable wrench.
3. Mark level and plumb lines onto the shower wall with a level. Indicate the horizontal and vertical centers of the existing shower valve.
4. Take the paper template that came with the new shower valve and hold it against the shower wall.
5. Align the template with the centerlines that you marked in Step 3, then trace the outline of the template onto the shower wall.
6. Use a drill/driver and 3/16-inch-diameter masonry bit to drill a series of close holes through the tiled wall. Be sure to drill the holes just inside the template outline.
7. Connect the holes by cutting through the tile using a hammer and 1/2-inch-wide cold chisel.
8. After chiseling through the tile, pull away the tiled wall section to expose the old shower valve. Use a drywall saw to trim away any ragged edges of drywall.
9. Use pliers to carefully twist off the tub spout. If there’s a setscrew beneath the spout, loosen it first before you try to remove the spout.
10. Remove the access panel from the rear of the shower wall. Use a reciprocating saw that’s fitted with a metal-cutting blade to cut through the pipe that connects the old valve to the shower head.
11. Loosen the threaded unions that secure the shower valve to the water-supply pipes with pliers. Remove and discard the old valve.
12. Cut short lengths of copper pipe and use them to join the new shower valve to the existing water-supply pipes, tub faucet and shower riser.
13. Brush flux onto the pipes and fittings, then solder the new valve into place.
14. Once you’ve installed the pressure-balance valve, move around to the tub side and screw on the finished escutcheon plate.
15. Wrap Teflon tape around the tub-spout stub-out, then thread on the new tub spout. Tighten the spout by hand. Don’t use pliers.
16. Screw the handle onto the center of the new shower valve.
17. Snap the index onto the handle to conceal the screw head.

Testing the Pressure Balance Valve for Leaks

Turn on the water supply gradually and check for leaks. Insufficient soldering or loose connections may cause leaks. Turn off the water supply and address any issues before you continue testing.

Adjusting Shower Water Temperature

Make sure the water temperature is consistent and does not fluctuate. Make minor adjustments until your shower is safe and comfortable.

Our Conclusion

Installing a pressure balance shower valve is a worthwhile upgrade for any bathroom. It enhances safety, improves shower comfort, and can potentially save water. The installation process requires some plumbing skills, but many homeowners with basic DIY experience can complete this project in a day, and make the shower experience safer and more enjoyable. 

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