Ceiling fan
A ceiling fan is a mechanical fan mounted on the ceiling of a room or space, usually electrically powered, suspended from the ceiling of a room, that uses hub-mounted rotating blades to circulate air. Ceiling fans typically rotate more slowly than other types of circulating fans, such as electric desk fans. They cool people effectively by introducing slow movement into the otherwise still, hot air of a room. Fans never actually cool air, unlike air-conditioning equipment, they in fact heat the air due to the waste heat from the motor and friction, but use significantly less power (cooling air is thermodynamically expensive). Conversely, a ceiling fan can also be used to reduce the stratification of warm air in a room by forcing it down to affect both occupants' sensations and thermostat readings, thereby improving climate control energy efficiency.
Ceiling protection switch
Ceiling protection switches are installed in secondary condensate drain pans in split system HVAC applications. The switch has a buoyant component that floats when the secondary condensate drain pan fills with water from the primary drain pan and shuts down the HVAC system to avoid overflowing. The ceiling protection switch is mainly used in applications where a piece of HVAC equipment is located in an attic or interior space where water damage is likely to occur. The switch does not guarantee the prevention of overflow, but may reduce the amount. Overflow water occurs when the condensate drain line becomes clogged restricting the flow of condensation from the interior to the exterior of the space. Overflow also occurs when an indoor HVAC coil becomes frozen, which when thaws creates excess water.