Weekends settings and setback functions for vacations.Programmable day and night settings of the set temperature.Short cycling of compressor will shorten its lifetime.
Some thermostat may have a feature called Emergency Heat where when set, it will shut off the heat pump. In this case the terminal W2 will be present. This is usually installed in regions where extreme winter occurred. Sometimes, there is a 2nd stage heating where additional heating is provided to supplement the primary heating system. In this case the terminal Y2 is usually used. In some equipment, there is a 2nd stage cooling that helps to increase the cooling capacity of the room. Only one connection is active at any one time, that is either O or B terminal is used but not both. If the reversing valve is turned on when running heat mode, you will need to connect the reversing valve to B terminal. The O terminal is used when the system that you are using has a reversing valve (or four way valve) which is turned on when running cooling mode. Therefore, it is important the check the manufacturer's specifications of the heat pump system that you are using before you can do a proper connection to the thermostat. However, there are instances where the reversing valve is off when running cool mode. In most cases, the reversing valve is energized when running cool mode.
The reversing valve is a device that reverses the flow of the refrigerant in the piping system. The G terminal is connected to the indoor fan which circulates the air in the room. This terminal will call for the need to cool the room when the set temperature is lower than the room temperature. The Y terminal is where the signal to the cooling air conditioner signal is connected. These two connections will ensure that there is power to the thermostat that you are operating. The color of wire R is usually RED and C is BLACK. Rectangular Air Ducts - Velocity Diagram - Velocity diagram for rectangular air ducts - metric units.Heat pump thermostat wiring - A typical wire color and terminal diagramĪs shown in the diagram, you will need to power up the thermostat and the 24V AC power is connected to the R and C terminals.HVAC Ducts - Air Velocities - Recommended air velocities in HVAC ducts.Ducts Sizing - the Velocity Reduction Method - The velocity reduction method can be used when sizing air ducts.Duct Velocity - Calculate velocities in circular and rectangular ducts - imperial and SI-units - online calculator.Circular Ducts - Dimensions - Standard size of circular ventilation air ducts.Air Ducts - Sizing - Required duct area vs.Air Ducts - Major Friction Head Loss, Online Calculator - Head loss or major loss in air ducts - equations and online calculator for rectangular and circular ducts - Imperial and SI units.