Carrier P374-1500 Owner's Manual page 19

About Advanced Features & Operation
MULTI-STAGE OPERATION - Control up to 3 Heat, 2 Cool Stages.
The 2nd Stage of heat or cool is
(A) the 1st Stage has been on meeting time required page13
(adjustable from 0-60 minutes, the default is 2) and
(B) the temperature spread
greater than: the setpoint
deadband, (this 2nd deadband is adjustable from 0-10 degrees,
the default is 2).
The 3rd Stage of Heat is turned on when:
The thermostat must be configured as a Advanced Heat Pump Thermostat,
Advanced Setup Step #4, off, page 12.
(A) the 2nd stage has been on meeting time required, page 13,
step #11, (also adjustable from 0-60 minutes, default = 2),
(B) the temperature from 2nd stage turn on plus the 3rd
deadband, (this 3rd deadband is adjustable from 0-10
degrees, the default is 2).
(C) the outside temperature is at or below the changeover
balance point, Advanced Setup Step #6, page 12.
Heating
Deadband Deadband
db 3 db 2
(adj. 0-10) (adj. 0-10)
3rd Stage 2nd Stage 1st Stage
turn on turn on turn on
The above figure assumes the minimum on time for the prior
stage has been met to allow the next stage to turn on,
once the deadbands have been exceeded and outside
temperature is below the changeover balance point.
turned on when:
from the setpoint is equal to or
plus the deadband, plus the 2nd
and
Cooling
Deadband Deadband Deadband
db 1 db 1
(adj. 1-6) (adj. 1-6) (adj. 0-10)
Heat Cool
Setpoint Setpoint
Page 18
,#10
db 2
1st Stage 2nd Stage
turn on turn on