Trane Foundation EBC180, Инструкция по установке, эксплуатации и обслуживанию

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26 RT-SVX50J-EN
Start Up
Electromechanical Controls -
Sequence Of Operation
These units are offered with electromechanical
controls.
N No otte e:: The Condensate Overflow Switch (COF)
(optional) will shut the unit down if the float is
raised and the switch is closed.
Cooling without an Economizer
When the thermostat switch is set to the "Cool"
position and the zone temperature rises above the
cooling setpoint, the thermostat Y contacts close. The
compressor contactor (CC1) coil is energized provided
the low pressure control (LPC1), high pressure control
(HPC1) and discharge line thermostat (DLT 1) are
closed. When the (CC1) contacts close, compressor
(CPR1) and both outdoor fan motors (ODM1 and
ODM2) start. If the first stage of cooling cannot satisfy
the cooling requirement, the thermostat closes Y2. The
compressor contactor (CC2) coil is energized provided
the low pressure control (LPC2), high pressure control
(HPC2) and discharge line thermostat (DLT 2) are
closed.
When the (CC2) contacts close, compressor (CPR2)
starts.
Evaporator Fan Operation (for Cooling
Only Units) - Standard Economizer
When the thermostat fan selection switch is set to the
"Auto" position, the thermostat energizes the indoor
fan relay coil (F) to start the indoor fan motor (IDM).The
fan relay (F) de-energizes after the cooling requirement
has been satisfied. When the heating cycle is
terminated, the indoor fan relay (F) coil is de-energized
with heater contactors.
When the thermostat fan selection switch is set to the
"On" position, the thermostat keeps the indoor fan
relay coil (F) energized for continuous fan motor
operation.
Economizer Set-Up - Standard
Economizer
Adjusting the minimum position potentiometer located
on the unit economizer module (RTEM-EM) sets the
required amount of ventilation air.
Ambient temperature is controlling the economizing
cycle by sensing the outside air dry bulb temperature.
Table 3, p. 26 lists the selectable dry bulb values by
potentiometer setting.
Table 3. Potentiometer settings
Potentiometer
Setting
Dry Bulb Enthalpy
A
27 Btu/lb (63 kJ/kg) 73°F (22.8°C)
B
25 Btu/lb (58 kJ/kg) 70°F (21.1°C)
C (a) 23 Btu/lb (53 kJ/kg) 67°F (19.4°C)
D
22 Btu/lb (51 kJ/kg) 63°F (17.2°C)
E
19 Btu/lb (44 kJ/kg) 55°F (12.8°C)
(a) Factory setting
Cooling with an Economizer - Standard
Economizer
The economizer is utilized to control the zone
temperature providing the outside air conditions are
suitable. Outside air is drawn into the unit through
modulating dampers.
When cooling is required and economizing is possible,
the unit economizer module (RTEM-EM) opens the
economizer damper. The RTEM-EM continues to
modulate the economizer damper open/closed to keep
the mixed air temperature in the 50°F to 55°F range.
The thermostat will close the Y2 contacts to turn on
contactor (CC1) if mechanical cooling is required.
If economizing is not possible, the RTEM-EM drives the
damper to the minimum position setpoint when the
indoor fan relay (F) is energized and allows mechanical
cooling operation.
Heating Operation (Units with Electric
Heat) - Standard Economizer
When the system switch is set to the "Heat" position
and the zone temperature falls below the heating
setpoint, the thermostat closesW1 contacts the first
stage electric heat contactor (AH or AH and CH) is
energized. If the first stage of electric heat cannot
satisfy the heating requirement, the thermostat closes
W2.
When the W2 contacts close, the second stage electric
heat contactor (BH or BH and DH) is energized, if
applicable. The thermostat cycles both the first and
second stages of heat "On" and "Off" as required to
maintain the zone temperature setpoint.
Ignition Module Low, Medium and High
Heat
Two-stage (IGN) runs self-check (including verification
that the gas valve is de-energized). (IGN) checks the
high-limit switches (TC01 and TC01) for normally
closed contacts, the pressure switch (PS) for normally
open contacts, and the flame rollout (FR) switch for