Leak Alarm Relay

Leak Alarm Relay OJ Electronics is a global supplier of thermostats, power controls, HVAC supplies and much more

Leak and Humidity Alarm Relay

NVP is an electronic unit capable of detecting moisture and water leakage, and is designed to protect installations and materials against condensation and bursting water pipes.
NVP is a safe and reliable alarm system, developed for use in both large and small installations where there is a need for early warning of condensation or pipe bursts. NVP has proved a success in many homes and offices. It is used in the building trade to monitor attics and roof voids in order to keep roof leak damage to a minimum. It is also fitted in HVAC installations to monitor condensation in cooled ceilings as well as pipe bursts.

NVP was designed to provide customers with an advantageous combination of high quality, reliability and low life cycle costs.

  • For use in both large and small installations
  • Can also be used to monitor attics and roof voids
  • Can be fitted to HVAC installations to monitor condensation





  • Why does the red LED light up the NVP, when there is no moisture on the sensor?


    The alarm is activated in two ways:

    • Sensor resistance to high - <900 kOhm (sensor loop interrupted)
    • Sensor resistance to low (Max: <570 kOhm Min: <50 kOhm)
  • Why is the alarm still activated on my NVP, when the sensor isn't wet any more?


    Contents of electrically conductive materials ( eg. rust, minerals, glycol) could be left behind on the sensor as it drys. Please change sensor.

  • I need an open circuit in case of leak or power outage. Which terminals do I use?


    Connection between terminal 5 and 7 is opened in case of an alarm.

  • What is the maximum sensor length?


    Sensor + wire combined can be >50 m. Please do not install near high power cables!

  • There is no interuption in the NVPF, cables or junctions, but the alarm is on. What causes the problem?


    If the resistance in the sensor loop is to high (>900 kOhm), please check if termination resistor (680 kOhm) is connected correctly. Please see "How do I connect sensor to relay"

  • How connect a sensor to a relay?


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