Control Selection Guide - Carrier 42 SERIES Application Data

Use this guide to make sure that all necessary components are provided for and that the components are compatible
with the required control system.
NOTE: When thermostatic fan control is selected or when unit outside air dampers are used, unit-mounted thermostats
are not recommended as their use will result in poor room temperature sensing.
SYSTEM DESCRIPTION
Fan Fan manually cycled
Control
(2-Pipe)
Thermostat cycles fan on-off
from speed set with
fan switch.
Thermostat cycles fan on-off
from fan speed set
with switch. Mode
automatically switched
by changeover
sensing water temp.
Thermostat cycles fan from
high to low on cooling
and low to off on heating.
Two- Thermostat cycles valve
position open or closed.
electric
valves
Thermostat cycles valve
(2-pipe)
open or closed.
Mode automatically
switched by changeover
sensing water temp.
Pneumatic Thermostat modulates
modulating pneumatic control valve.
valves
(2-pipe)
Two- Thermostat cycles valve
position open or closed. 2° F after
electric valve closes, thermostat
valve with activates electric heater.
Auxiliary Heater can't turn on
Electric if hot water is in coil.
Heat
Thermostat cycles valve
(2-pipe)
open or closed. Manual
changeover switch
changes thermostat to
heat to activate electric
heater.
Two- Thermostat cycles valve
position open or closed.
electric Manual changeover switch
valve with changes thermostat to heat
total to activate electric heater.
electric
Thermostat cycles valve
heat
open or closed.
(2-pipe)
2° F after valve closes,
thermostat activates
electric heater.
Pneumatic Thermostat modulates
modulating pneumatic control valve.
valves After changeover,
(2-pipe) thermostat
activates electric heater.
Two- Thermostat cycles
position cooling and heating
electric valves open or closed.
valves
(4-pipe)
Thermostat cycles cooling
valve open or closed. 2° F
after valve closes,
thermostat cycles
heating valve open or closed.
Pneumatic Thermostat modulates
modulating cooling valve.
valves After changeover,
(4-pipe) thermostat modulates
heating valve.
*If system is HEATING-ONLY or COOLING-ONLY, no changeover or bypass is required.
NOTE: Unit-mounted thermostats are not recommended with either fan-cycle control or applications with outside air dampers.

CONTROL SELECTION GUIDE

CHANGEOVER
THERMOSTAT ON
SUPPLY PIPE
None None
Wall mounted None
includes heat-cool
switch.
Wall mounted. Yes
Heating/cooling
Thermostat
Wall or unit Yes
mounted
Wall mounted None
includes heat-cool
switch.
Wall or unit Yes
mounted.
Heating/cooling
Thermostat
By others. By others.
Wall or unit Yes.
mounted. Sequenced Two Required.
heating and cooling.
Wall mounted None
includes heat-cool
switch.
Wall mounted None
includes heat-cool
switch.
Wall or unit None
mounted.
Sequenced heating
and cooling
By others. By others.
Wall mounted None
includes subbase
with heat-cool
switch.
Wall or unit None
mounted.
Sequenced heating
and cooling.
By others. By others.
3
FAN
VALVE
SWITCH (SW)
None Standard
3-Speed SW
None Thermostat has
integral
3-Speed SW
None Standard
3-Speed SW
None No Standard
3-Speed Switch,
ON-OFF toggle SW
only
Motorized (N.C.) Thermostat
3-way or 2-way, has integral
no bypass required. 3-Speed SW
Motorized (N.C.) Standard
3-way or 2-way 3-Speed SW.
Others have
thermostats with
integral 3-Speed SW
2- and 3-way Standard
furnished by others. 3-Speed SW
Can be equipped
with factory
assembled
valve package.
Motorized Standard
3-way or 2-way 3-Speed SW
Others have
thermostats with
integral 3-Speed SW
Motorized Thermostat
3-way or 2-way, has integral
no bypass required 3-Speed SW
Motorized (N.C.) Thermostat
3-way or 2-way, has integral
no bypass required 3-Speed SW
Motorized (N.C.) Standard
3-way or 2-way, 3-Speed SW
no bypass required
2- and 3-way Standard
furnished by others. 3-Speed SW
Can be equipped
with factory
assembled
valve package.
Motorized (N.C.) Thermostat
3-way or 2-way has integral
(requires 2 valves) 3-Speed SW
Motorized (N.C.) Standard
3-way or 2-way 3-Speed SW.
(requires 2 valves) Others have
thermostats
with integral
3-Speed SW
2- or 3-way Standard
furnished by others. 3-Speed SW
Can be equipped
with factory
assembled
valve package.
NOTES
Not recommended
for high humidity
application
Unit mounted
thermostats provide
very poor room
temperature control
Best fan cycle
control for
high humidity
applications
Valve packages
with belled end(s)
for field soldering
to coil.
Factory assembled
in valve package
w/flare nuts.
Valve packages
with belled end(s)
for field soldering
to coil.
Valve packages
with belled end(s)
for field soldering
to coil.
Valve packages
with belled end(s)
for field soldering
to coil.
Valve packages
with belled end(s)
for field soldering
to coil.
Factory assembled
in valve package
w/flare nuts.
Valve packages
with belled end(s)
for field soldering
to coil.
Valve packages
with belled end(s)
for field soldering
to coil.
Factory assembled
in valve package
w/flare nuts.
Valve packages
include unions for
for field assembly
to coil.