5.2-Stage Compressor Units with Newer ECONWMT Economizers (See Note A)
1st stage cooling set point is the setting (SP) input into the controller. Factory default is 77F (25C). On a call for cooling the blower of the lead unit will come on immediately (if not already on – See Blower Operation), and the Stage 1 LED will blink for 10-seconds before going solid, at which time the lead unit Y1 cooling output turns on. If the outdoor temperature and humidity conditions are below the set point of the economizer control the lead unit economizer will operate instead of the compressor. If outdoor conditions are not acceptable for free cooling the compressor will automatically operate on compressor Stage 1 partial capacity instead of the economizer.
2nd cooling set point is 4F (default setting, user selectable 2-6F) warmer than Stage 1. On a call for 2nd stage cooling the lead unit Y2 cooling output turns on. If the outdoor temperature and humidity conditions are below the set point of the economizer control the lead unit economizer will continue to operate, and the compressor will operate on compressor Stage 1 partial capacity. If the compressor is already operating on Stage 1 partial capacity because outside free cooling range the compressor will switch to compressor Stage 2 full capacity.
3rd cooling set point is 2F (default setting, user selectable 2-3F) warmer than Stage 2. On a call for 3rd Stage cooling the blower of the lag unit will come on immediately (if not already on – See Blower Operation), and the Stage 3 LED will blink for 10-seconds before going solid, at which time the lag unit Y1 cooling output turns on. The lag unit economizer will operate if the outdoor temperature and humidity conditions are below the set point of the economizer control. If outdoor conditions are not acceptable for free cooling the compressor will automatically operate on compressor Stage 1 partial capacity instead of the economizer.
4th cooling set point is 2F (default setting, user selectable 2-3F) warmer than Stage 3. On a call for 4th Stage cooling the lag unit Y2 cooling output turns on activating the compressor. If the outdoor temperature and humidity conditions are below the set point of the economizer control the lag unit economizer will continue to operate, and the compressor will operate on compressor Stage 2 full capacity. If the compressor is already operating on Stage 1 partial capacity because outside free cooling range the compressor will switch to compressor Stage 2 full capacity.
Note A: Economizers in ECONWMT-Series are available with either “T” temperature only outdoor sensor or “E” enthalpy (temperature and humidity) outdoor sensor. The “T” versions will have a fixed (but selectable) outdoor temperature decision whereas on the “E” versions the outdoor temperature decision will float based on outdoor humidity and the selected Enthalpy curve in the economizer control module.
HEATING SEQUENCE OF OPERATION
Note: All heating sequences for air conditioners with electric heat or heat pumps will automatically operate in Alternating Lead/Lag/Lead/Lag sequence even if controller is set to Non-Alternating for cooling with or without economizers.
1.Air Conditioners with Electric Heat
1st stage heating set point is the dead-band (db) below the 1st stage cooling set point (the SP entered into the program). The dead-band is adjustable from 2-40F, and factory default is 17F.
2nd stage heating set point will operate at same inter- stage differential as set for cooling mode.
2.Heat Pumps with Electric Heat
When the MC4000 controller is configured for heat pump installations the 2nd-stage (Y2) outputs for both units 1 and 2 are redefined and used to control the reversing valves, and which are energized in heating mode.
1st stage heating set point is the dead-band (db) below the 1st stage cooling set point (the SP entered into the program). The dead-band is adjustable from 2-40F, and factory default is 17F.
1st-stage heating consists of lead unit blower coming on (if not already on – See Blower Operation), and reversing valve being energized. The Stage 1 heating LED will blink for 10-seconds, at which time the compressor turns on.
2nd heating set point is 4F (default setting, user selectable 2-6F) cooler than Stage 1. On a call for 2nd Stage heating the blower of the lag unit is turned on (if not already on
–See Blower Operation), the reversing valve is energized, and the Stage 2 LED will blink for 10- seconds before going solid, at which time the compressor will start.
3rd-stage heating will be the electric heater, if so equipped, in the lead unit. Stage 3 heating LED comes on solid with no blinking.
4th-stage heating will be the electric heater, if so equipped, in the lag unit. Stage 4 heating LED comes on solid with no blinking.
