Jackson Systems Comfort System T-21-P User Manual page 4

Mode selection
The T-21-P can control both heating and cooling. Touch the Mode box to cycle through and select
available modes. Based on equipment and thermostat configuration, mode selection can be as
follows:
PM
Fan selection
Touch the Fan box to select
operates with a heating or cooling call. If set to Always On, the fan will run continuously. If the
thermostat is turned Off while the fan is set to Always On, the fan will switch to Automatic mode but
can be set back to Always On for constant ventilation when the thermostat is Off.
Heat Set
Heat
Day
Automatic or Always On
PM
Off - Thermostat will not call for heating or
cooling.
Heat - Thermostat only controls heating.
When heating system is running,
flashes.
Cool - Thermostat only controls cooling.
When cooling system is running,
flashes.
Auto - Thermostat controls both heating and
cooling. Heat
equipment is running.
E. Heat - Emergency heat for heat pump
systems should the compressor fail.
fan mode. In Automatic mode, the fan
Heat Set
Heat
Day
3
Heat
Cool
or Cool will flash when