DIY Network

How to Install a Pressure Reducing Valve

Ed the Plumber explains how to install a pressure reducing valve with these step-by-step instructions.

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Step 1: Install the Pressure Reducer Valve

Install the pressure reducer valve as close to the main water shut off as possible to protect the entire house.

Double check to make sure the home has high water pressure. Put the gauge on an outside sillcock or on the water heater. Because of the amount of water in the water heater, the gauge may read a little bit higher than normal, but not enough to throw the reading off.

installing the pressure reducer valve

Step 2: Shut Off the Water and Water Heater; Drain the System

Shut off the water at the main valve and to the water heater.

Turn off your water heater at the breaker if electric, or if gas, turn the switch to the pilot position.

Drain the home's plumbing system by opening the highest and lowest faucets.

Step 3: Perform a Loop Back Installation

Pressure reducer valves are usually installed in an in-line application; the line goes in one side and out the other. If there isn't enough room for the fittings and the valve is in a small space, a loop back installation will have to be performed.

Start by using a pipe cutter to remove a section of pipe from the main water line. Be sure to have a bucket close by to catch any water in the line.

remove a section of pipe from main water line

Step 4: Remove and Clean the Pipe

Remove the pipe and make sure all the water is out of the line.

Clean both ends with a plumber's sand cloth.

Clean the inside and outside of a 90-degree elbow, coupling and male adaptor.

Use a deburring tool to remove any burrs on the inside of the fittings.

Step 5: Apply Flux, and Attach the Elbow

Apply flux to the fittings as well as to each end of the cut section of the main water line.

Attach the elbow, the coupling and the adaptor.

apply flux and attach elbow

Step 6: Solder an Extension Piece

Heat the fittings with a torch, and then add solder to each joint.

Apply Teflon paste to the mounted fitting. Unscrew the union from the reducing valve, mount to the fitting, and then screw into place. Use plumber's wrenches to tighten.

With the union in place, it's time to mount the pressure reducer valve. One end of the valve will have a threaded connection. Put an extension piece on, solder the whole assembly away from the valve, and then screw it back into place.

Step 7: Attach the Reducing Valve and the Union

Clean, flux and attach the adaptor to the extension piece.
Heat the fittings and apply solder. Make sure the fitting is cool before picking up.

Apply Teflon paste, and then screw the pressure reducing valve into the union, making sure the fitting marked "in" is attached to the main water line. Tighten with plumbers wrenches.

Step 8: Attach Elbows and a Coupling to the Extension

Clean and flux three 90-degree elbows and a coupling. Attach one elbow to the extension piece from the reducing valve, and then a coupling followed by the second elbow.

Clean and flux a measured section of copper pipe, and then attach the prepared elbow to the copper pipe.

Mount the fitting to finish the loop to the water line.

clean and flux measured section of copper pipe

Step 9: Solder the Joints, and Turn on the Water

Make sure the assembly is securely fastened, and then solder all the joints to complete the installation of the water pressure reducing valve.

Once the joints have cooled, it's time to turn the water back on. Start by turning on the water heater again, and then slowly opening up the main valve. Be sure to check for leaks.

solder all joints to complete installation

Step 10: Install the Water Hammer Arrestors

Now that the water pressure reducer is finished, go over to your washing machine, faucet or dishwasher and install the water hammer arrestors. Isolation valves make the job of installing the water hammer arrestors very simple.

Turn off the hot and cold water lines.

Unscrew the hoses attached to the hot and cold water lines and at the washing machine, faucet or dishwasher.

Step 11: Attach Hammer Arrestors

Screw a water hammer arrestor to the valve of the hot water line and do the same for the cold water line. Use a wrench to securely tighten.

Screw a braided stainless steel hose to both the hot water line at the dishwasher and faucet. Again, use a wrench to tighten if necessary.

Turn the water back on to complete the project.

attach water hammer arrestors