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
Newer digital thermostats have no moving parts to measure temperature and instead rely on thermistors or other semiconductor devices such as a resistance thermometer (resistance temperature detector). Typically one or more regular batteries must be installed to operate it, although some so-called "power stealing" digital thermostats use the common 24 volt AC circuits as a power source, but will not operate on thermopile powered "millivolt" circuits used in some furnaces. Each has an LCD screen showing the current temperature, and the current setting. Most also have a clock, and time-of-day and even day-of-week settings for the temperature, used for comfort and energy conservation. Some advanced models have touch screens, or the ability to work with home automation or building automation systems.