Computer room server racks with temperature sensors

Choosing a wireless temperature monitoring system for your space

A wireless temperature monitoring system is one of many critical tools in a server room environment.  Wireless temperature monitoring can be deployed in data closets, server rooms, or data center applications. Over the years, wireless sensor monitoring has become a much more viable option. Whether using Temperature, Temperature/Humidity, Differential Pressure, Leak Detection, or other models, wireless could be a great option for your application needs. In overview, battery life and sensor transmission distance are two of the big factors. Furthermore, being able to easily add and replace sensors makes maintaining a system much easier, without having to contact your vendor all the time. Then looking at system integration, open protocols are key to be in the selection. Open protocols such as Modbus, BACnet, and SNMP open up the flexibility of your wireless system to communicate to multiple platforms. With this in mind, some systems that require a server-based solution may cost extra for drivers that support open protocols. Protocols such as OPC or XML may be available, but do not work with all remote monitoring platforms. We cover some key pieces using a wireless temperature monitoring system.

Wireless sensor battery life

Battery life can be a big cost if the battery needs to be replaced frequently. In this case, the gateway should alarm on a low-level or depleted battery. The larger the server room means more cost to maintain the battery style used.

  • Wi-Fi: These sensors run the battery down the fastest (4 – 12 months on average life)
  • 400 MHz: 2 – 4 year span with a single battery
  • 900 MHz: 2 – 10 year span with a single battery
  • 1.5V Lithium ION Battery – AA cell size ($2.75/Battery Avg Cost)
  • 3.6V Lithium ION Battery – AA cell size ($9.75/Battery Avg Cost)
  • 3.0V Lithium ION Battery – 2032 Coin cell size ($0.95/Battery Avg Cost)

Wireless sensor frequency

In general, sensors that use a higher frequency get less distance overall.

  • Wi-Fi 2.4 GHz – 5 GHz: Up to 100ft (30.48m) line of sight transmission
  • Wi-Fi 2.4 GHz – 5 GHz: Poor transmission through obstructions (crowded network)
  • 400 MHz: Up to 100ft (30.48m) line-of-sight transmission
  • 400 MHz: Poor transmission through/around obstructions
  • 900 MHz: Low wattage (0.1w) up to 600ft (182.88m) line-of-sight transmission
  • 900 MHz: Good transmission through/around obstructions

Sensor data sent to the wireless temperature monitoring system

Equally important, is how the sensor data is being sent to the base unit.

  • WiFi 2.4 GHz – 5 GHz: To point out, you are a node on the network
  • This means you are probably using a network maintained by IT
  • The network could be scanned for threats or cyber security concerns  
  • 400 MHz – 900 MHz: In general, use a proprietary broadcast signal
  • Segregated wireless network traffic is not part of the main IT network

The time between transmissions from temperature sensors

How often does the sensor send data? In general, this point does not come up till later in system design conversations. When data is required every 60 seconds, and the system does not update sensor values for every 5 minutes, that might be a deal-breaker.

  • Sensors can vary from every 10 seconds to once every 5 minutes

Wireless temperature monitoring system to be Standalone, Integrated or both

Nonetheless, no one wants a wireless temperature monitoring system with limited capability. When starting off, a system that can send email notifications gives you initial alarm updates while planning to integrate to another platform. In the event you want redundancy, you can leave the email notification enabled, while your other system also handles alerts.

  • Wireless temperature monitor that supports trending of data
  • Easy to add sensors to an existing system
  • Email notification
  • System integration such as Modbus, BACnet, and SNMP
  • In addition, supports multiple sensor types
  • Temperature
  • Temperature/Humidity
  • Differential Pressure
  • Leak Detection


Given these points, what data points do you want to collect? 10+ years ago, distance and battery life were not ideal. Today, generally speaking, users have options on sensor types with wireless sensors and how to integrate that data into other systems. It is important to realize, Line-of-sight from the sensor to the receiver is key to avoiding dead spots. WiFi 2.4 GHz – 5 GHz commonly use your companies network.  With this in mind, your device is potentially therefore seen as a cyber threat To repeat, having a system that can provide a web interface and send email notifications is key. Furthermore, having open protocols allows your system to expand. In conclusion, we understand not all applications are the same. If you would like to discuss an application, please feel free to contact us at FMS Integration LLC.