53
Operation
Unit operations must be controlled with a unit
controller, never at the main power supply,
except for emergency or complete shutdown
of the unit.
Packaged DX Cooling Operation
When a call for cooling (G and Y1, Y2, etc.)
is made the supply fan motors and
compressors will energize.
Note:
When using field controls any variable
capacity compressors must run at 100% for 1
minute when starting.
Indirect Gas Heater Operation
When heat (G and W1, W2, etc.) is called for
the combustion motor starts and the ignition
control is energized. The control sends 24
VAC to the gas valve and high voltage to the
igniter. If a burner flame has been detected
within 10 seconds, the spark is extinguished
and the flame continues. If a flame has not
been detected after 10 seconds, the gas valve
closes, the spark ceases and the induced draft
blower
continues
to purge the heat
exchanger. After 45 seconds of purge, the
ignition system will attempt to light the
burners again. Should no flame be detected
after 3 tries, the ignition control will lock out
the system. Power to the ignition control
must be cycled to reset the heater control.
On a fault the gas train is shut down by a main
limit located in the heat exchanger area or by
an auxiliary limit mounted in the supply fan
compartment.
Electric Heating Operation
When a call for heating (G and W1, W2, etc.)
is made the supply fan motors and electric
resistance heaters will energize. Heating is
accomplished by passing electrical current
through a specified amount of resistance
heaters which will produce the required heat.
On a fault condition the main limit located in
the supply air or the auxiliary limit located
downstream of the supply fan will remove
power from all contactors.
Steam or Hot Water Preheating and
Heating Operation
Valve control for steam and hot water heating
coils are by others. Heating is accomplished
by passing steam or hot water through the
steam or hot water coil assembly.
Chilled Water or Non-Compressorized
DX Cooling Operation
Controls for chilled water cooling coils and
non-compressorized DX coil are by others.
COMPRESSOR CYCLING
3 MINUTE MINIMUM OFF TIME
To
prevent
motor
overheating
compressors must cycle off for a
minimum of 3 minutes.
5 MINUTE MINIMUM ON TIME
To maintain the proper oil level
compressors must cycle on for a
minimum of 5 minutes.
The cycle rate must not exceed 7
starts per hour.
WARNING
Summary of Contents for RZ Series
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Page 31: ...31 Figure 4 4 Point Lift RZ Series Air Cooled Condenser Unit ...
Page 90: ...90 Gas Heater Operating Instructions ...
Page 108: ...108 Maintenance Log E Coated Coil ...
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