A low UV output alarm can only be displayed if a UV sensor is installed in a UV system. Many different factors can cause the UV intensity reading to be low when a UV sensor is installed. If low UV intensity is detected, the low UV alarm will be lit, and the system alarm will sound.

When determining the cause of a UV alarm, the first step is to perform a water quality test. It is important that water quality parameters fall within the specifications below.

Hardness:                        < 7 gpg (120 mg/L)

Iron (Fe):                          < 0.3 ppm (0.3 mg/L)

Manganese (Mn):       < 0.05 ppm (0.05 mg/L)

Turbidity:                   < 1 NTU

Tannins (organics):       < 0.1 ppm (0.1 mg/L)

UVT (transmittance):   > 85%

If the water quality falls outside the requirements, pre-filtration must be installed to resolve the issue. If the water quality falls within the requirements above, a dry test should be performed following the directions below.

Dry Test Procedure

• Shut off the water source.
• Unplug the controller from the power source.
• De-pressurize the chamber and drain water.
• Clean and dry the sensor and reinstall.  Reference article
• Clean and dry the quartz sleeve and reinstall. Reference article
• With the water still shut-off, plug the controller into the power source.
• Check the UV intensity. If 100%, the UV sensor is operating normally.

If the dry test shows a good result, other possible causes of low UV alarms are:

• Air bubbles in water.
  • This can be tested by taking a water sample after the UV system in a clear glass. Look to see if bubbles form. If they do, there are air bubbles in the water. This must be purged from the water supply before the UV system.
• Water temperatures outside of the operating range.

If the UV sensor is displaying a low UV intensity during a dry test, or if the cause for the alarm is undetermined after troubleshooting, please submit a ticket for support. New Ticket