Page 86
C1 DIAGRAM CONNECTED TO B35 or B36 DIAGRAM
Electromechanical Thermostat with ThreePhase Commercial Units
2-C1 Section Connected to B35 Section
OPERATION SEQUENCE: 208/230V THREEPHASE UNITS (TOP)
All units equipped with Crankcase Heater, High Pressure Switch, Loss of Charge
Switch and low voltage terminal strip.
1- Line voltage energizes transformer T1. Transformer T1 provides 24VAC power to all unit con
trols, economizer (if used) and thermostat.
2- Compressor crankcase heater is self-regulating and is powered at all times.
3- Cooling demand energizes Y1 and G in the thermostat. Y1 passes through pressure switches
S4 and S24 to energize compressor contactor K1. G energizes relay K3.
4- K1-1 closes to energize compressor and condenser fan. Both immediately begin operating.
5- K3 contacts 7-4 close to energize the indoor blower on cooling speed. Contacts 6-9 close to
energize the economizer.
6- Heating demand energizes W1 in the thermostat. Heating demand energizes relay K13.
Heating demand also passes through (secondary high temperature limit S21 -
GCS16(R)-413-100 only) and high temperature limit S10 to combustion air prove switch S18.
7- Relay K13 terminals 4-7 close to energize combustion air blower B6. Terminals 6-9 close to
energize the economizer. When the combustion air blower nears full speed, prove switch S18
closes. Heating demand passes through S18 and through flame rollout switch S47 to energize
ignition control (A3) terminal 1.
8- Ignition control A3 then waits 30 to 40 seconds to allow combustion air blower B6 time to draw
exhaust gas from combustion chamber and to introduce fresh air. Combustion air blower B6
operates throughout the heating cycle.
9- After ignition control delay, A3 activates gas valve GV1, time delay K25 and the spark elec
trode. When flame is sensed by the flame sensor (minimum 5 microamps) the spark electrode
stops. If flame is not sensed after the first trial for ignition, controller A3 repeats steps 8 through
9 up to two more times (depending on controller make) before locking out. Delay relay K25
delays 60 seconds before closing.
If the control locks out, it can be reset by breaking and remaking thermostat demand.
10- After the 60 second delay, relay K25 closes to energize the indoor blower on heating speed.
3-C1 Section Connected to B36 Section
460V and 575V units are equipped with a unique blower motor. The blue motor lead is not a
speed tap. It is used only to complete an internal circuit when the motor is operating at low or
medium speed. Refer to unit components section of this manual for more information.
OPERATION SEQUENCE: 460/575V THREEPHASE UNITS (ABOVE)
All units equipped with Crankcase Heater, High Pressure Switch, Loss of Charge
Switch and Low Voltage Terminal Strip.
1- Line voltage energizes transformer T1. Transformer T1 provides 24VAC power to all unit con
trols, economizer (if used) and thermostat.
2- Transformer T3 is used in all 460V and 575V units. T3 provides 230VAC to combustion air
blower B6. The transformer is powered at all times.
3- Transformer T4 is used in 575V units only. T4 provides 460VAC to indoor blower B3. Re
duced voltage is provided to the common leg of the blower. It is powered at all times.
4- Compressor crankcase heater is self-regulating and is powered at all times.
5- Cooling demand energizes Y1 and G in the thermostat. Y1 energizes compressor contactor
K1. G energizes relay K3.
6- K1-1 closes to energize compressor and condenser fan. Both immediately begin operating.
7- K3 contacts 7-1 open to disconnect heating speed. K3 contacts 8-2 open to disconnect the
internal circuit (blue leg) and contacts 5-8 close to energize blower B3 on cooling speed.
8- K3 Contacts 6-9 close to energize the economizer.
9- Heating demand energizes W1 in the thermostat. Heating demand energizes relay K13.
Heating demand also passes through (secondary high temperature limit S21 -
GCS16(R)-413-100 only) and high temperature limit S10 to combustion air prove switch S18.
10- Relay K13 terminals 4-7 close to energize combustion air blower B6. Terminals 6-9 close to
energize the economizer. When the combustion air blower nears full speed, prove switch S18
closes. Heating demand passes through S18 and through flame rollout switch S47 to energize
ignition control terminal 1.
11- Ignition control A3 then waits 30 to 40 seconds to allow combustion air blower B6 time to draw
exhaust gas from combustion chamber and to introduce fresh air. Combustion air blower B6
operates throughout the heating cycle.
12- After the ignition control delay, A3 activates gas valve GV1, time delay K25 and the spark elec
trode. When flame is sensed by the flame sensor (minimum 5 microamps) the spark electrode
stops. If flame is not sensed after the first trial for ignition, controller A3 repeats steps 11
through 12 up to two more times (depending on controller make) before locking out. Delay
relay K25 delays 60 seconds before closing.
If the control locks out, it can be reset by breaking and remaking thermostat demand.
13- After the 60 second delay, relay K25 closes to energize relay K20.
14- K20 terminals 4-7 close to energize the indoor blower on heating speed. K3 terminals 8-2 re
main closed to complete an internal circuit.
To Next Page
Loading...