Smart thermostat
Another major feature of smart thermostats is their ability to connect to the internet. Smart thermostats are designed with a WiFi module that allows the thermostat to connect to the users home or office network and interface with a web portal or smartphone application, allowing users to control the unit remotely. The WiFi feature also has the ability to send reports on energy usage and HVAC system performance via the web portal, informing the user on their energy efficiency and how it compares to other smart thermostat users. It also alerts users when a problem arises with their HVAC system or when it is time for equipment maintenance. The thermostat also uses the WiFi connection to display current weather conditions and the weather forecast.
Thermostat
Electromechanical thermostats use resistance elements as anticipators. Most electronic thermostats use either thermistor devices or integrated logic elements for the anticipation function. In some electronic thermostats, the thermistor anticipator may be located outdoors, providing a variable anticipation depending on the outdoor temperature. Thermostat enhancements include outdoor temperature display, programmability, and system fault indication. While such 24 volt thermostats are incapable of operating a furnace when the mains power fails, most such furnaces require mains power for heated air fans (and often also hot-surface or electronic spark ignition) rendering moot the functionality of the thermostat. In other circumstances such as piloted wall and "gravity" (fanless) floor and central heaters the low voltage system described previously may be capable of remaining functional when electrical power is unavailable.