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Home > Support > Troubleshooting your HVO System
Troubleshooting your HVO System
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Diagnostic Procedure

Please go through each of the following steps BEFORE you request support:


  1. Check for tripped circuit breakers. Check that every outlet that you are using works properly. To test, plug a working tool like a hand drill or a lamp into each outlet. If you have a voltmeter, you can use that.
  2. Check the INTERNAL compressor breaker switch (see photo). If the logic board is on but the compressor isn’t running, you may have experienced a power surge that tripped the internal breaker switch. Press the breaker button to reset.

  3. Check the connections to all your coaxial cables. If the cables seem worn or have an intermittent connection, replace with new coax cables. When the system is running use a voltmeter to see if 24v DC power is running through the cable. If you don’t have a voltmeter, you may want to visit the hardware store and get a cheap one. It’s important to have one for quick problem solving, and it can be difficult to solve tricky problems without one.
  4. Check the oxygen concentrators. Unplug the concentrator from the relay box and unscrew the brass fitting to the manifold. One at a time, plug the concentrator directly into a working wall outlet (you can use an extension cord for this).
  5. Check oxygen flow using the flow meter on the oxygen concentrator. This assumes that you have a flow meter. If you don’t, you may want to invest in one. Verify that each of the concentrators is producing an adequate flow of oxygen. Does the liter-per-minute flow rate rise or fall as you turn the knob on the flowmeter?
  6. Check the oxygen percentage of every oxygen concentrator. If you have an oxygen analyzer, measure the output of each oxygen concentrator. HVO sells a Handheld Ultrasonic Oxygen Analyzer, if you would like to purchase one.
  7. Verify relay box power. One at a time, test each relay box separately by running a (tested, known-to-be-working) coax cable directly from the Main to one relay box at a time and turn on the Main. Note that the tank pressure must be below the low setpoint for this to work. If necessary, release some oxygen from the tank so that the Main turns on.
  8. Check the dump valve assembly. If the compressor is running and you can feel air coming out of the clear line under the headbox, this means that the dump valve isn’t closing. A new dump valve may be needed.
  9. Test the Drone. Run a working coax cable directly from the Main to the Drone. Make sure the Drone power switch is in the “on” position, the cable is fully tightened, and the cord is snug in the back. Plug the Drone directly into a free outlet separate from the Main. Disconnect the oxygen inlet hose on the back of the Drone and check for a vacuum. Listen to determine if the Drone compressor is coming on. If it’s humming but not coming on (no vacuum) turn it off immediately and call service.
  10. When you reconnect the system, check all cords, cables, and connections. Power cords and cables can come loose over time from vibration. Coax cables can jam and seem fully tightened when they’re still loose. Wiggle the screw connector and keep trying to move the nut until it is tight (tighten only by hand).
  11. Eliminate non-functional components. Pull out any non-functional concentrators and/or relay boxes. You can often assemble a temporary system with the working components while others are being serviced.

WARNING: Never operate the HVO system with the oxygen concentrators powered off but still connected to the manifold unless the flow valves are turned all the way to zero. Running atmospheric air through concentrators that are powered off could cause permanent damage to the sieve beds. The best practice is to disconnect the oxygen line from each non-functional concentrator and plug the hole in the manifold where they were removed.

Possible installation issues:

  1. Building wiring problems:
    • Power fluctuations or shared circuits with insufficient power
    • Sometimes a lightning strike can cause blown circuits. The HVO circuits should reset but some concentrators have external pop off fuses that need to be reset.
    • Trying to run your system off of a generator that doesn’t produce enough power
  2. Insufficient ventilation. In an airtight space, nitrogen build-up / oxygen depletion can occur. Ensure that you have adequate ventilation that pulls in outside air. A rule-of-thumb is to plan for 100 CFM per 10 LPM oxygen concentrator. Thus, a system with six oxygen concentrators would require 600 CFM of air flow.
  3. Ambient temperature is above or below what is recommended for PSA oxygen concentrators. Practically all models operate best between 45 – 90℉, with humidity below 85%, although humidity of less than 50% is optimal.

Low oxygen percentage can be caused by:

  1. Concentrator flow rate dialed too high
    • Flow meters should be dialed to just below the top flow rate. For example, a 10 LPM oxygen concentrator should be dialed back to 9-9.5 lpm.
  2. Power isn’t reaching oxygen concentrators:
    • Not all concentrators are plugged in
    • Relay box or circuit-breaker tripped
  3. Leak in the manifold. Check all the oxygen lines.
    • Check that the brass fitting is securely seated on the barb of the oxygen concentrator. Hand tighten fittings. Do not use tools on the brass fittings that connect the oxygen lines to the oxygen concentrators.
    • Check the manifold (clear plastic oxygen) lines at the push-to-connect fittings. If necessary, cut off the ends of the lines to make a flush cut, and re-insert into push to connect manifold or connection.
  4. Concentrators that use a mechanical power switch work best with the HVO system. Some concentrators (e.g. Sequal Integra) use an electronic power switch that doesn’t turn back on even though the relay box is calling for power.
    • Plug your concentrator directly into the wall and turn it on. Disconnect power cord, wait 10 seconds and plug it back in. If the concentrator does not power back on, it may not work with the HVO system.

NOTE: If you have an issue with a Drone, there’s a simple temporary fix: Disconnect the oxygen input hose in the back of the Drone and reconfigure the manifold so that all of the oxygen that was going to the Drone is redirected to the Main or other working Drones. The system will run at reduced efficiency, but may be a useful short-term alternative.

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