For this sequence the thermostat must be configured for two (2) stages of cooling.
Note: When a thermostat is configured for (2) stages of cooling, (Y) enables the first stage of cooling and (Y2) enables the second stage of cooling.
High Cooling Demand - the room temperature starts 1.1°F or more above its thermostats cool set point:
- At the beginning of the cooling cycle the thermostat will start the supply fan.
- If the thermostat has high cooling demand (the room temperature is 1.1°F or more above the cool set point), it will start its first stage of cooling and then, one minute later, it will start its second stage of cooling.
- Both stages of cooling will remain active until the room’s temperature drops to 1°F above its thermostats cool set point, at which point the thermostat will then turn Off the second stage of cooling and keep the first stage of cooling enabled until the room reaches its cool set-point.
- If the room’s temperature raises back to 1.1°F or more above the cool set point, while the first stage of cooling is running, the thermostat will re-enable the second stage of cooling and use both the first and second stages of cooling to bring the room to its cool set-point.
Note: There is a built-in 4 minute short cycle delay between when a cool stage last turned off and when it will be re-enabled to allow the oil pressure to rebalance at the compressor.
Low Cooling Demand - the room temperature starts 1.0°F or less above its thermostats cool set point:
- At the beginning of the cooling cycle the thermostat will start the supply fan.
- If the thermostat has low cooling demand (the room temperature is 1°F or less above the thermostats cool set point), it will start its first stage of cooling and give the first stage the opportunity to provide all the necessary cooling to condition the room.
- The first stage of cooling will remain active until the room reaches its thermostats cool set-point.
- If while the first stage of cooling is active, the room’s temperature goes 1.1°F or more above the thermostat’s cool set point, the thermostat will start the second stage of cooling and used both the first and second stages to bring the room to its cool set-point.
Note: There is a built-in 4 minute short cycle delay between when a cool stage last turned off and when it will be re-enabled to allow the oil pressure to rebalance at the compressor.
Why this staging sequence?
This staging sequence accomplishes two goals:
- It quickly cools the room in high cooling demand situations, and then relaxes the number of stages to provide a more comfortable supply temperature and cooling rate when the room is just being maintained.
- It allows for the greatest efficiency value to comfort ratio.
What will you see on a thermostat's history graph?
On the thermostat’s history graph you will see the following:
- The dark blue line shows the room temperature.
- The light blue horizontal line shows the thermostats cool set-point.
- A light blue shaded area indicates the thermostat has started a cooling cycle.
- If one stage of cooling is/are active, there will be a single grey bar at the bottom of the blue shaded area.
- If two stages of cooling is/are active, there will be two grey bars (one stacked on top of the other) at the bottom of the blue shaded area.
