Layered monitoring
Instead of relying on one measurement, monitor ambient temperature, the air-conditioner alarm contact, and network availability of critical devices as separate signals. NetRelay digital inputs can read dry contacts, while a compatible external analog module can support suitable temperature sensors.
Threshold and delay design
Add delay or hysteresis to the threshold to avoid alarms from brief temperature fluctuations. Separate warning and critical levels. Do not treat this arrangement as a life-safety or certified fire-detection system; it is intended for operational monitoring.
Network health and controlled action
Ping Watchdog can monitor up to four targets. When a device becomes unreachable, creating an alert or log entry first is usually safer; use an automatic power cycle only when the equipment manufacturer's operating procedure permits it.
Logging and testing
Send measurements to a central system over MQTT or HTTP, or plan local logging with a MicroSD module. Test sensor disconnection, network loss, and high-temperature conditions separately, and document who receives each alarm, through which channel, and within what response time.