Pressure Problems
Isolating a loss of pressure can be a challenge. Assuming you have verified there is adequate, unrestricted water flow to
the high-pressure pump, any pressure-building issues will be caused by one of three components:
Here is how to systematically troubleshoot and resolve issues with each component.
1. The Pressure Control Valve (Needle Valve)
If mineral scale builds up on the valve's needle and seat, it prevents the valve from creating the precise restriction needed to build system pressure.
How to Inspect the Needle:
How to Clean Scale from the Valve Body:
Important: Never stick hard objects, metal tools, or wire into the valve body. Even a tiny scratch risks permanently ruining the valve seat.
2. The Pressure Relief Valve (PRV)
The PRV is a safety device that dumps water overboard if the system over-pressurises. It relies on a stainless steel spring which, unlike high-carbon steel, relaxes over time and loses its "memory". Eventually, it may start dumping water well below your 800 psi operating threshold.
The Symptom: The system suddenly drops to around 200 psi while you are dialing in pressure. Winding the control valve further does nothing, but unwinding it fully and starting again allows pressure to build briefly before dropping again.
How to Reset and Calibrate the PRV:
Tip: This works best as a two-person job—one to monitor the pressure gauge and control panel, and one to adjust the valve.
3. The High-Pressure Pump
The high-pressure pump is the least likely culprit in a low-pressure scenario, but when failures do occur, they break down into two possibilities:
Issue A: Plunger Seals
Plunger seals prevent high-pressure water from leaking past the ceramic plungers. While they generally last for years, running the pump dry or without enough water flow causes extreme heat build-up that destroys the seals.
Issue B: Debris in the Check Valves
The pump contains 6 check valves (an inlet and an outlet valve for each of the 3 plungers) located behind the 6 cylindrical hex-socket caps on the pump head. If marine debris or scale gets trapped between a valve's internal poppet and seat, it won't seal properly, causing a massive drop in pressure efficiency.
How to Clean the Check Valves:
the high-pressure pump, any pressure-building issues will be caused by one of three components:
- The Pressure Control Valve (Needle Valve)
- The Pressure Relief Valve (Safety PRV)
- The High-Pressure Pump
Here is how to systematically troubleshoot and resolve issues with each component.
1. The Pressure Control Valve (Needle Valve)
If mineral scale builds up on the valve's needle and seat, it prevents the valve from creating the precise restriction needed to build system pressure.
How to Inspect the Needle:
- Loosen the cap-nut located directly behind the control knob.
- Wind the knob all the way out until the needle assembly comes completely out of the valve body.
- The needle should be clean and shiny. If it is coated in scale or debris, wipe it completely clean with a soft rag.
How to Clean Scale from the Valve Body:
Important: Never stick hard objects, metal tools, or wire into the valve body. Even a tiny scratch risks permanently ruining the valve seat.
- Reinsert the needle assembly and tighten the cap-nut until the turning resistance on the knob feels familiar.
- Wind the stem all the way in, then gently over-tighten the needle to crush and break apart the scale built up on the seat. To do this securely, wrap the knob in a rag and use large pliers to tighten it just a fraction further (about 5 to 10 degrees).
- Next, wind the knob all the way back out to the fully open position.
- Run your boost pump for 5 minutes to flush the shattered scale out of the system. While the pump is running, wind the valve in and out a few times to ensure the seat clears completely.
2. The Pressure Relief Valve (PRV)
The PRV is a safety device that dumps water overboard if the system over-pressurises. It relies on a stainless steel spring which, unlike high-carbon steel, relaxes over time and loses its "memory". Eventually, it may start dumping water well below your 800 psi operating threshold.
The Symptom: The system suddenly drops to around 200 psi while you are dialing in pressure. Winding the control valve further does nothing, but unwinding it fully and starting again allows pressure to build briefly before dropping again.
How to Reset and Calibrate the PRV:
Tip: This works best as a two-person job—one to monitor the pressure gauge and control panel, and one to adjust the valve.
- Plumb a temporary drain: Loosen the hose clamp on the PRV fitting. Disconnect the discharge line and plug it so water doesn't spill back out of the system. Run a temporary 1/2” hose from the PRV hose-tail directly into a bucket. Do not clamp this temporary hose.
- Loosen the thin locking nut on the PRV, then wind the large cap-nut all the way in until it bottoms out in the valve body.
- Start up the watermaker normally with the product water valve set to Sample.
- Have your helper monitor the gauge while you slowly bring the system pressure up to 1050 psi.
- Slowly loosen off the cap-nut on the PRV. Keep winding it out until the valve opens and the pressure drops (the gauge needle may flicker before dropping sharply to under 200 psi).
- With the system still running (and dumping safely into your bucket), drop the pressure using the main control valve, then bring it back up. The PRV should now dump pressure consistently somewhere between 950 psi and 1050 psi. Fine-tune the cap-nut until it hits this target window.
- Turn off the high-pressure pump, tighten the thin lock-nut securely, remove your temporary line, and reconnect and tighten your original discharge hose.
3. The High-Pressure Pump
The high-pressure pump is the least likely culprit in a low-pressure scenario, but when failures do occur, they break down into two possibilities:
Issue A: Plunger Seals
Plunger seals prevent high-pressure water from leaking past the ceramic plungers. While they generally last for years, running the pump dry or without enough water flow causes extreme heat build-up that destroys the seals.
- The Symptom: Water will actively leak or drip from the weep holes/vents located on the bottom of the pump, right where the brass manifold meets the crankcase. If this is happening, the plunger seals must be replaced.
Issue B: Debris in the Check Valves
The pump contains 6 check valves (an inlet and an outlet valve for each of the 3 plungers) located behind the 6 cylindrical hex-socket caps on the pump head. If marine debris or scale gets trapped between a valve's internal poppet and seat, it won't seal properly, causing a massive drop in pressure efficiency.
How to Clean the Check Valves:
- Remove a valve cap using a 3/8 inch Allen key.
- Using a pair of pliers, gently grasp the small plastic protrusion on top of the valve cage and rock it upward to lift it out of the chamber.
- Inspect the valve assembly. It should be clean and shiny. The internal poppet should lift off its seat easily, and the spring should snap it back into place smoothly.
- If you notice any salt, discolouration, or debris on the mating surfaces, clean it thoroughly in fresh water. An old toothbrush is perfect for scrubbing the poppet and seat. (Note: While replacement valve kits are available, a good clean solves the issue most of the time).
- Peer inside the pump's valve chamber. Clean out any salt crust or scale, and ensure the rubber O-ring at the very bottom of the chamber is clean and undamaged.
- Press the clean check valve firmly back into place, and securely torque the valve cap back down.
- Repeat this exact process for the remaining 5 valves.
