Technical Guide: Resetting Your Pressure Relief Valve

The Pressure Relief Valve (PRV) is a vital safety mechanism designed to protect your watermaker from over-pressurisation. While the nominal operating pressure of the system is 800 psi, the high-pressure pump is capable of building more than twice that amount.
​
To safeguard your components, the PRV is factory-set to open and dump pressure if it ever climbs above a safety threshold of 1050 psi.

Step-by-Step Reset Procedure

Tip: This procedure is best done with two people—one to adjust the valve at the pump, and one to operate the control panel.
​
  1. Plug the discharge line: Remove the hose from the PRV (located on the high-pressure pump) and plug the end of the hose. Because this hose is T’d into the discharge circuit, plugging it is necessary to prevent water from spilling out.​​                             
  2. Set up a temporary line: Run a temporary 1/2” hose from the hose-tail on the PRV into a bucket. Do not fit a hose clamp.
  3. Bottom out the valve: Loosen the locking nut on the PRV, and wind the cap-nut (with the hose-tail attached) all the way in until it bottoms out.
  4. Bring system to threshold: Run the watermaker following your standard quick-start guide. Slowly bring the system pressure up to 1050 psi. Be incredibly careful not to allow it to climb any higher than this.
  5. Set the relief point: Slowly unwind the cap-nut on the PRV until the valve opens. This will likely happen suddenly. As soon as it does, quickly wind down the pressure on your main control valve.
    • Note: When the pressure drops to around 200 psi, the internal poppet in the PRV will re-seat. Continue unwinding the main control valve until the system is at zero pressure, then shut off the high-pressure pump.
  6. Lock it down: Tighten the lock-nut on the pressure relief valve to lock in the new setting, then re-connect your original discharge hose.
  7. Test run: Start the watermaker up normally to confirm the system functions correctly and holds pressure at 800 psi.

Why does it need to be reset?

The PRV is regulated by a stainless steel spring. Because stainless steel springs do not have the same "memory" as standard high-carbon steel springs, the valve may require resetting once or twice over the lifetime of your watermaker.

How to tell if your valve needs resetting

You will know the PRV needs adjustment if the system suddenly drops in pressure to around 200 psi. This typically happens while you are actively dialing in the pressure on your way up to 800 psi.
  •