Carrier 42 SERIES - Manual (Page 6)

STANDARD WIRING PACKAGES (cont)
Thermostatic 2-Pipe Auxiliary Electric Heat
with Valve Control —
This system, also called Twi-
light or Intermediate Season electric heat, goes a long way
towards solving the spring and fall control problems of 2-pipe
systems.
You can run chilled water late into the fall, turn it on early
in the spring and still have heat available to all units when-
ever required.
In winter the system is switched over to hot water. Two
changeover devices are required for this. One device switches
the action of the thermostat and the other locks out the elec-
tric heat when hot water is in the coil.
With this system, the fan runs continuously unless manu-
ally switched to OFF position. Fan must be on before ther-
mostat can send signal to open chilled water valve or turn on
electric heater.
Two control methods are available:
1. Use the standard automatic changeover thermostat with a
dead band between heating and cooling, or —
2. Use a manual changeover thermostat. With this method
only one changeover is required.
Be sure to include a 2-way or 3-way electric valve with
this system.
NOTE: Wiring diagrams are for 120-v power supply. If other
voltages for heaters or controls are specified,wiring may dif-
fer from that shown.
For control package descriptions, see control components
sections entitled Remote-Mounted Controls and Unit-
Mounted Controls.
UNIT
TYPE
LOCATION
WIRING PACKAGE* ELECTRIC
VALVE Automatic System Manual System
Vertical
Unit
Mounted
24-Q Available on Special Order.
Any 2- or 3-way,
2-position valve
Package.
Vertical
or
Horizontal
Wall Mounted
22-J, 22-K,
23-09, 23-10
23-15, 23-16
*Packages on current price pages.
NOTES:
1. Motors are thermally protected.
2. Use copper conductors only.
3. See unit nameplate for power supply. Provide disconnect means
and overload protection as required.
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