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Using Monnit Wireless Sensors to Remotely Monitor HVAC Systems

Keywords: sensor installation, AC system, air conditioning, heating systems


How to install Monnit wireless sensors for tracking and monitoring air conditioning and HVAC systems.

To get started, we suggest purchasing a Monnit HVAC Monitoring starter bundle as it will include all the devices needed to remotely monitor one HVAC or boiler system. Bundles can be purchased here. Alternately you can purchase the devices separately if you wish to use a different gateway or coin cell version of some sensors for the indoor portion of the installation.

The devices we recommend are:
    1 - Wireless Gateway
    1 - Industrial Wireless Quad Temperature Sensor
    1 - Industrial Wireless AC Current Meter (150 Amp)
    1 - Wireless Duct Temperature Sensor
    1 - Wireless Temperature Sensor

AC System Installation

Before starting any part of this installation process, shut the power off to both the condenser unit and the inside air handler unit. For the indoor portion of the HVAC monitoring system, start by installing a Monnit wireless gateway. The gateway can be located anywhere in the building where it has access to power and a decent cellular signal (for Cellular gateways) or access to an internet router (Ethernet gateways) or PC (USB gateways). For indoor sensors, we recommend using a wireless duct temperature sensor to monitor the output ventilation air that is being sent from the air handling unit back to the building and a wireless temperature sensor that can be installed near the thermostat or air return, to track ambient room temperature.

Overview of Monnit remote monitoring solutions for HVAC systems

For the outside condenser unit, we recommend using a Monnit industrial wireless quad temperature sensor as it comes in a weatherproof enclosure suitable for outdoor use. The quad temperature sensor has 4 independent temperature probes that can monitor and collect temperature readings for the key areas of the condenser unit. Each temperature probe is labeled 1 through 4.

Start by connecting one of the temperature probes to the suction line, one to the liquid line and another one to the discharge line making note of which probe you are connecting to each. When connecting a temperature probe to any of these refrigerant lines, we recommend using a zip tie to securely fasten the probe tight against the bare metal tube. After securing the temperature probe use thermal tape to completely wrap the probe to the refrigerant line, this provides a thermal barrier allowing the sensor to get a more accurate reading of the refrigerant line temperature. For the remaining probe, we recommend fastening one to the fan grate to capture the discharge air temperature. Alternately you can use any of the probes to capture ambient outdoor temperature if you prefer.

Installing Monnit sensors on an AC condenser unit

We also suggest using a Monnit industrial wireless AC meter (150 Amp) to track the current draw of the compressor. The AC meter uses a clip-on current transformer that should be clipped around the "hot" power wire feeding the compressor.

With the sensors installed, you can restore power to the condenser and air handling units. The system will begin tracking data for you. If your AC system is cooling efficiently you should see an average difference of 16-19°F (in humid areas) and 19-22°F (in dry areas) between the intake air and outgoing air returning to the building. When monitoring the current consumption of the compressor, an increase in the amount of current being used signifies that the compressor may need to be serviced or replaced.