Carrier 42 SERIES - Manual (Page 3)

CONTROL SELECTION GUIDE
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 THERMOSTAT
CHANGEOVER
ON
SUPPLY PIPE
VALVE
FAN
SWITCH (SW)
NOTES
2-PIPE
HEA
TING-COOLING*
Fan
Control
(2-Pipe) Fan manually cycled None None None Standard
3-Speed SW Not recommended
for high humidity
application
Thermostat cycles fan on-off
from speed set with
fan switch. Wall mounted
includes heat-cool
switch. None None Thermostat has
integral
3-Speed SW
Thermostat cycles fan on-off
from fan speed set
with switch. Mode
automatically switched
by changeover
sensing water temp. Wall mounted.
Heating/cooling
Thermostat Yes None Standard
3-Speed SW Unit mounted
thermostats provide
very poor room
temperature control
Thermostat cycles fan from
high to low on cooling
and low to off on heating. Wall or unit
mounted Yes None No Standard
3-Speed Switch,
ON-OFF toggle SW
only Best fan cycle
control for
high humidity
applications
Two-
position
electric
valves
(2-pipe) Thermostat cycles valve
open or closed. Wall mounted
includes heat-cool
switch. None Motorized (N.C.)
3-way or 2-way,
no bypass required. Thermostat
has integral
3-Speed SW Valve packages
with belled end(s)
for field soldering
to coil.
Thermostat cycles valve
open or closed.
Mode automatically
switched by changeover
sensing water temp. Wall or unit
mounted.
Heating/cooling
Thermostat Yes Motorized (N.C.)
3-way or 2-way Standard
3-Speed SW.
Others have
thermostats with
integral 3-Speed SW
Pneumatic
modulating
valves
(2-pipe) Thermostat modulates
pneumatic control valve. By others. By others. 2- and 3-way
furnished by others.
Can be equipped
with factory
assembled
valve package. Standard
3-Speed SW Factory assembled
in valve package
w/flare nuts.
Valve packages
with belled end(s)
for field soldering
to coil.
ELECTRIC
HEA
T
Two-
position
electric
valve with
Auxiliary
Electric
Heat
(2-pipe) Thermostat cycles valve
open or closed. 2° F after
valve closes, thermostat
activates electric heater.
Heater can’t turn on
if hot water is in coil. Wall or unit
mounted. Sequenced
heating and cooling. Yes.
Two Required. Motorized
3-way or 2-way Standard
3-Speed SW
Others have
thermostats with
integral 3-Speed SW Valve packages
with belled end(s)
for field soldering
to coil.
Thermostat cycles valve
open or closed. Manual
changeover switch
changes thermostat to
heat to activate electric
heater. Wall mounted
includes heat-cool
switch. None Motorized
3-way or 2-way,
no bypass required Thermostat
has integral
3-Speed SW Valve packages
with belled end(s)
for field soldering
to coil.
Two-
position
electric
valve with
total
electric
heat
(2-pipe) Thermostat cycles valve
open or closed.
Manual changeover switch
changes thermostat to heat
to activate electric heater. Wall mounted
includes heat-cool
switch. None Motorized (N.C.)
3-way or 2-way,
no bypass required Thermostat
has integral
3-Speed SW Valve packages
with belled end(s)
for field soldering
to coil.
Thermostat cycles valve
open or closed.
2° F after valve closes,
thermostat activates
electric heater. Wall or unit
mounted.
Sequenced heating
and cooling None Motorized (N.C.)
3-way or 2-way,
no bypass required Standard
3-Speed SW
Pneumatic
modulating
valves
(2-pipe) Thermostat modulates
pneumatic control valve.
After changeover,
thermostat
activates electric heater. By others. By others. 2- and 3-way
furnished by others.
Can be equipped
with factory
assembled
valve package. Standard
3-Speed SW Factory assembled
in valve package
w/flare nuts.
Valve packages
with belled end(s)
for field soldering
to coil.
4-PIPE
Two-
position
electric
valves
(4-pipe) Thermostat cycles
cooling and heating
valves open or closed. Wall mounted
includes subbase
with heat-cool
switch. None Motorized (N.C.)
3-way or 2-way
(requires 2 valves) Thermostat
has integral
3-Speed SW Valve packages
with belled end(s)
for field soldering
to coil.
Thermostat cycles cooling
valve open or closed. 2° F
after valve closes,
thermostat cycles
heating valve open or closed. Wall or unit
mounted.
Sequenced heating
and cooling. None Motorized (N.C.)
3-way or 2-way
(requires 2 valves) Standard
3-Speed SW.
Others have
thermostats
with integral
3-Speed SW
Pneumatic
modulating
valves
(4-pipe) Thermostat modulates
cooling valve.
After changeover,
thermostat modulates
heating valve. By others. By others. 2- or 3-way
furnished by others.
Can be equipped
with factory
assembled
valve package. Standard
3-Speed SW Factory assembled
in valve package
w/flare nuts.
Valve packages
include unions for
for field assembly
to coil.
*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.
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