115/230VAC or Line Voltage
The control voltage for line voltage systems (like baseboard heat) takes a special line voltage thermostat.
The control voltage for low voltage systems (gas, elec, oil, etc).
How close the thermostat reads the actual room temperature.
The circulating fan inside the house.
A device in mechanical thermostats to heat the thermostat when the heat is running to shut the thermostat off early.
A thermostat mode that automatically switches to the HEAT or COOL program as needed.
Separate 2nd source of heat, generally electric strips.
The back part of some thermostats that mounts to the wall and also where the HVAC system wires connect.
Lights up the thermostat display for use in the dark. Electro luminescent panel behind the LCD display that glows a gentle blue white when the backlight button is pressed.
The Common side of a 24VAC system often used to run the thermostat instead of or with batteries.
Allows the changing of the room temperature reading on most digital thermostats.
A pump that moves the refrigerant in an A/C or heat pump.
The minimum time the thermostat allows a compressor to cycle off and back on to prevent compressor stall.
A compressor must be off for a few minutes (approx. 5) before it can be turned back on or the compressor might not start.
A device that removes moisture from the air. An air conditioner naturally removes moisture from the air during normal operation.
See Also: humidifier
Two stages of heat and/or two stages of cool, LOW and HIGH.
See Also: multi stage
Heats and Cools using a single heat exchanger.
A device on the furnace that adds moisture to the air.
The volume of water vapor is in the air.
Heating, Ventillation, Air Conditioning.
The small plastic devices that connect pins on the back of the thermostat circuit board for making various selections shown in the manuals.
The wire connecting the RC and the RH terminals.
The HVAC system is not cycling on and off enough.
See Also: short cycling
The control voltage for some gas fireplaces, heaters, etc.
A multi stage thermostat can control multiple sources of heating and/or cooling.
Standards for wiring thermostats.
The requested temperature set on the thermostat.
The HVAC system is cycling on and off too often.
See Also: long cycling
A device which cools by adding moisture to the air via evaporation.
Sets the temperature spread between the heat or cool on and off temperatures.
Swing is the temperature difference between where a system comes on and then goes off. EXAMPLE: The thermostat is set at HEAT, a target temperature set at 70F, and the swing number set at 3 (+/-1F). The heat would typically come on at 69 and go off at 71. Most thermostats have the ability to set swing.
See Also: set point
A thermostat controls one or more of the HVAC functions.
A Time Slot is one of the four parts the thermostat divides the progam day into: Morning(MORN), Day(DAY), Evening (EVEN), and Night (NITE). All 4 time slots must reside in the same 24 hour day.
A unit with a display screen that can be changed and programmed by touching the displayed icons on the screen.
A piece of plastic that mounts at the wall in back of the thermostat to help cover a whole in the wall.
Connecting thermostats to HVAC systems.
See Also: Thermostat Wiring Chart
A zoned HVAC system uses a series of dampers to selectively heat/cool different areas (zones) when necessary.
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