47
N.C.
N.O.
M
M
AO - Mixed air dampers
(optional)
OA
DA
M
BO - Fan start/stop
AI - Discharge air temp
(optional)
HP
BO - Compressor stage 1
BO - Compressor stage 2
Elec
BO - Heating stage 1
(optional)
BO - Heating stage 2
(optional)
BO - Reversing valve
T
T
AI - Zone temp
AI - Zone setpoint adjust
BI - Zone override
TT
BI - Freezestat
(optional)
AI - Outside air temp
(optional)
Zone temp X Internal
Zone setpoint
adjust
X Internal
Zone override X Internal
Outdoor air temp X UI-1 Optional – Requires sensor
(Type II thermistor)
Short input to ground if
not used.
Discharge air temp X UI-2 Optional – Requires sensor
(Type II thermistor)
Freezestat X UI-3 Optional – Requires sensor
(dry contact)
Compressor stage 1 X DO-1 (Y1) Relay output
Compressor stage 2 X DO-2 (Y2) Relay output
#2: Air source heat pump - reverse to heat
Control schematic
Point list