Step 7 · Test for Leaks
Once the solder joints have completely cooled, reinstall the valve cartridge according to the manufacturer's directions. Place a rag or small bucket inside the wall under the valve. Go to the main water shutoff and turn it on SLOWLY. Listen for the sound of pipes filling. Return to the access panel and meticulously inspect every solder joint for any drips or beads of water. If you find a leak, you will need to shut off the water, drain the system, and re-solder the faulty joint. Also, test the valve function by turning the handle to run water to the tub spout and shower head.