26 506 01 2303 01
Specifications are subject to change without notice.
OPERATING SEQUENCE
Base Unit Controls
Indoor (Supply) Fan —
The i ndoor fan contactor (IFC) is remotely loca ted at the
fan coil or fan section. If the thermostat fan operation is
selec ted as Continuous, the IFC is energize d and the
indoor (supply) fan motor runs continuously. If t he
thermostat fan operation is selected as Automatic, the IFC
will be energized on a call for Cooling or Heating; indoor
(supply) fan motor runs. When t hermostat is sati sfied, the
IFC is de-energized a nd indoor (supply) fan motor stops.
Cooling, Unit Without Economizer --
Single Stage Units—
When thermostat calls fo r Cooling, terminal Y 1 is energized.
The CHS’s Defrost Board (DF B) receives this input at P 2-5.
DFB iss ues 24-v outputs at OF, P3-7 (RVS1) and P3-10
(COMP 1). The OF output energizes outdoor fan relay
(OFR); both outdoor fan motors start and run. The output
RVS1 energizes the revers ing valv e solen oid (RVS);
Reversing valve switches to Cooling position.
Output PL3-10 (COMP1, 24-v) is received at CADM
terminal Y. If anti-recycle time delay period has not
expired, safe ty pressure switches are open, and/or lockout
alarms are active, CADM relay will remain open,
preventing compressor start. When safety pressure
switches are closed and CADM time delay expires, the
CADM relay closes, energizing Solenoid Valve Relay
SVR and compressor contactor C. SVR contacts close,
energizing the external liquid line solenoid valve.
Solenoid va lve LLSV opens. Compressor contactor C
closes, energizing the compressor motor. Compressor
starts and system runs in Cooling mode .
When space cooling load is satisfied, terminal Y1 is
de-ene rgize d. Compressor and outdoor fan motors stop.
Liquid line solenoid valve LLSV is de-energized and
valve closes. CADM begins its three-minute anti-recycle
time delay.
If either the Loss of Charge (LOC) Switch or High
Pressure Switch (HPS) opens while Y1 remains energized,
the compressor contactor C and relay SVR are
de-ene rgized; compressor stops and liquid line solenoid is
de-energized (valve closes). CADM initiates a TRIP event
(cooling demand sensed at CADM terminal Y but no
current is measured at T1, T2, T3 motor sensors); CADM
relay opens and RED LED is illuminated. TRIP condition
maintains lockout of compressor operation until CADM is
manua lly reset . Reset CADM by cycling unit main power.
Reversing valve solenoid (RVS) is energized in Cooling
modes. This solenoid will remain energized until the next
Heating mode is initiated.
Cooling, Unit Without Economizer --
Two--Stage Units—
For two stage units, the CHS072*G/H uses a two--stage
Copeland Ultratech Scroll compressor in conjunction with
a two--stage Comfort Alert Module (CADM). The
CHS121*G/H uses two compressors i n tandem on a single
circuit in conj unction with two single--stage Comfort Alert
Modules (CADM).
CHS072*G/H
When thermostat calls for Stage 1 Cooling, terminal Y1 is
energized. The CHS’s Defrost Board (DFB) receives this
input at P2--5. DFB issues 24--v outputs at OF, P3--7
(RVS1) and P3--10 (COMP1). The OF output e nergizes
outdoor fan relay (OFR); both out door fan motors start
and run. The output RVS1 energizes the re versing valve
solenoid (RVS); Reversing valve switches to Cooling
position. Output PL3--10 (COMP1, 24-- v) is received at
CADM terminal Y. If anti --recycle time delay period has
not expired, safety pressure switches are open, and/or
lockout alarms are active, CADM relay will remain open,
preventing compressor start. When safety pressure
switches are closed and CADM time delay expires, the
CADM relay closes, energizing Solenoid Valve Relay
SVR and compressor contactor C. SVR contacts close,
energizing the external liquid line solenoid valve.
Solenoid va lve LLSV opens. Compressor contactor C
closes, energizing the compressor motor. Compressor
starts and system runs in Stage 1 Cooli ng mode.
When thermostat calls for Stage 2 Cooling, terminal Y2 is
energized. The CHS’s Defrost Board (DFB) receives this
input at P2--4. DFB issues 24--v outputs at OF, P3--8
(COMP2). Output PL3-- 8 (COMP2, 24--v) is received at
CADM terminal Y2. CADM DC SOL terminal outputs
24--vdc to the compressor loader plug (LDR) and the
compressor opera tes at full load capacity.
As space cooling l oad is satisfied, thermostat outputs Y2
and Y1 are sequentially de--energized, removing 24--v a t
terminals Y2 and Y1. Compressor Loader plug is
de--energized on Y2 opening. On Y1 opening, the
Compressor stops, al l outdoor fan motors stop and SVR
rela y is de--energized. Liquid line solenoid val ve is
de--energized and valve closes. CADM begins its
three-- minute anti--recycle time delay.
If either the Loss of Charge (LOC) Switch or High
Pressure Switch (HPS) opens while Y1 remains
energized,the compressor contactor C and relay SVR are
de--energized; compressor stops and liquid line solenoid i s
de--energized (valve closes). CADM initiates a TRIP
event (cooling demand sensed at CADM terminal Y but
no current is measured at T1, T2, T3 motor sensors);
CADM relay opens and RED LED is illuminated. TRIP
condition maintains lockout of compressor operation until
CADM is manually reset. Reset CADM by cycling unit
main power. Reversing valve solenoid (RVS) is energized
in Cooling modes. This solenoid will remain energized
until the next Heating mode is initiated.
CHS121*G/H
When thermostat calls for Stage 1 Cooling, terminal Y1 is
energized. The CHS’s Defrost Board (DFB) receives this
input at P2--5. DFB issues 24--v outputs at OF, P3--7
(RVS1) and P3--10 (COMP1). The OF output e nergizes
outdoor fan relay (OFR); both out door fan motors start
and run. The output RVS1 energizes the re versing valve
solenoid (RVS); Reversing valve switches to Cooling
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