26
Completing Heater Installation
FIELD POWER CONNECTIONS
Tap conductors must be installed between the base unit’s field
power connection lugs and the single point box (with or without
fuses). See Fig. 32. Refer to unit wiring schematic. Use copper
wire only. For connection using the single point box without fuses,
connect the field power supply conductors to the heater power
leads and the field-supplied tap conductors inside the single point
box. Use UL approved pressure connectors (field-supplied) for
these splice joints.
LOW-VOLTAGE CONTROL CONNECTIONS
Pull the low-voltage control leads from the heater module(s) -
VIO and BRN (two of each if two modules are installed; identify
for Module #1) - to the 4-pole terminal board TB4 located on the
heater bulkhead to the left of Heater #1. Connect the VIO lead
from Heater #1 to terminal TB4-1. Connect the VIO lead from
Heater #2 to terminal TB4-2. Connect both BRN leads to terminal
TB4-3. See Fig. 35.
SMOKE DETECTORS
Smoke detectors are available as factory-installed options on
50TCQ models. Smoke detectors can be specified for supply air
only, for return air with or without economizer, or in combination
of supply air and return air. Return-air smoke detectors are ar
-
ranged for vertical return configurations only. All components
necessary for operation are factory-provided and mounted. The
unit is factory-configured for immediate smoke detector shutdown
operation; additional wiring or modifications to unit terminal
board can be necessary to complete the unit and smoke detector
configuration to meet project requirements.
System
The smoke detector system consists of a four-wire controller and
one or two sensors. Its primary function is to shut down the roof
-
top unit in order to prevent smoke from circulating throughout the
building. It is not to be used as a life saving device.
Controller
The controller (see Fig. 39) includes a controller housing, a print
-
ed circuit board, and a clear plastic cover. The controller can be
connected to one or two compatible duct smoke sensors. The clear
plastic cover is secured to the housing with a single captive screw
for easy access to the wiring terminals. The controller has three
LEDs (for Power, Trouble and Alarm) and a manual test/reset but
-
ton (on the cover face).
Fig. 39 —
Controller Assembly
Sensor
The sensor (see Fig. 40) includes a plastic housing, a printed cir
-
cuit board, a clear plastic cover, a sampling tube inlet and an ex
-
haust tube. The sampling tube (when used) and exhaust tube are
attached during installation. The sampling tube varies in length de
-
pending on the size of the rooftop unit. The clear plastic cover per
-
mits visual inspections without having to disassemble the sensor.
The cover attaches to the sensor housing using four captive screws
and forms an airtight chamber around the sensing electronics.
Each sensor includes a harness with an RJ45 terminal for connect
-
ing to the controller. Each sensor has four LEDs (for Power, Trou
-
ble, Alarm, and Dirty) and a manual test/reset button (on the left-
side of the housing).
Air is introduced to the duct smoke detector sensor’s sensing
chamber through a sampling tube that extends into the HVAC duct
and is directed back into the ventilation system through a (shorter)
exhaust tube. The difference in air pressure between the two tubes
pulls the sampled air through the sensing chamber. When a suffi
-
cient amount of smoke is detected in the sensing chamber, the sen
-
sor signals an alarm state and the controller automatically takes
the appropriate action to shut down fans and blowers, change over
air handling systems, notify the fire alarm control panel, etc.
The sensor uses a process called differential sensing to prevent
gradual environmental changes from triggering false alarms. A
rapid change in environmental conditions, such as smoke from a
fire, causes the sensor to signal an alarm state but dust and debris
accumulated over time does not.
For installations using two sensors, the duct smoke detector
does not differentiate which sensor signals an alarm or trouble
condition.
Duct smoke sensor
controller
Fastener
(2X)
Controller cover
Conduit nuts
(supplied by installer)
Conduit support plate
Cover gasket
(ordering option)
Conduit couplings
(supplied by installer)
Terminal block cover
Controller housing
and electronics
Alarm
Power
Test/reset
switch
Trouble
Summary of Contents for WeatherMaker 50TCQ 17-24 Series
Page 35: ...35 Fig 53 RTU Open Overlay for Economizer Wiring ...
Page 36: ...36 Fig 54 VFD Overlay for W2770 Controller Wiring ...
Page 68: ...68 Fig B 50TCQD17 24 Control Wiring Diagram APPENDIX D WIRING DIAGRAMS ...
Page 69: ...69 Fig C 50TCQD17 24 Power Wiring Diagram 208 230 3 60 Units APPENDIX D WIRING DIAGRAMS ...
Page 70: ...70 Fig D 50TCQD17 24 Power Wiring Diagram 460 3 60 575 3 60 Units APPENDIX D WIRING DIAGRAMS ...
Page 71: ...71 Fig E RTU Open Overlay APPENDIX D WIRING DIAGRAMS ...
Page 72: ...72 Fig F PremierLink Overlay APPENDIX D WIRING DIAGRAMS ...