Step 6 · Secure the Adjustment
Once the water pressure is consistently holding within your target range, you must lock the adjustment in place to prevent it from changing over time due to vibrations. Use one wrench to hold the adjustment bolt head firmly in its final position. With your other wrench, turn the locknut clockwise until it is snug against the body of the PRV. It should be firm, but do not overtighten, as this can strip the threads or damage the valve.