York D2CG300 User Manual
switch is in the “AUTO” position, the blower will operate only
when there is a call for heating by the thermostat.
when there is a call for heating by the thermostat.
b) Upon a call for first-stage heat by the thermostat, the heater
contactor (6M) (6M & 7M on 72 KW, 240V) will be
energized.
If the second stage of heat is required, heater contactor
(7M) will be energized. Note that on the 54 KW, 240V
heater, heater contactors (7M & 8M) will be energized and
on the 72 KW, 240V heater, heater contactors (8M & 9M)
energized.
If the second stage of heat is required, heater contactor
(7M) will be energized. Note that on the 54 KW, 240V
heater, heater contactors (7M & 8M) will be energized and
on the 72 KW, 240V heater, heater contactors (8M & 9M)
will be energized.
c) The thermostat will cycle the electric heat to satisfy the
heating requirements of the conditioned space.
HEAT ANTICIPATOR SETPOINTS
It is important that the anticipator setpoint be correct. Too high of
a setting will result in longer heat cycles and a greater temperature
swing in the conditioned space. Reducing the value below the
correct setpoint will give shorter “ON” cycles and may result in the
lowering of the temperture within the conditioned space. Refer to
the Heat Anticipator Setpoints table for the required .
a setting will result in longer heat cycles and a greater temperature
swing in the conditioned space. Reducing the value below the
correct setpoint will give shorter “ON” cycles and may result in the
lowering of the temperture within the conditioned space. Refer to
the Heat Anticipator Setpoints table for the required .
GAS HEATING SEQUENCE OF OPERATION
The following sequence describes the operation of the gas heat
section.
CONTINUOUS BLOWER
With the room thermostat switch set to “ON”, the supply air
blower will operate continuously. The normally closed contact
“K5-1" provides 24 volt power to the “3M” contactor. The “3M-1,
2 & 3" power contacts close and the blower motor operates.
INTERMITTENT BLOWER
With the room thermostat system switch set to the “AUTO” or “HEAT”
position and the fan switch set to “AUTO”, the supply air blower will
operate after the room thermostat calls for heat and the time delay
relay closes.
The “TH1" closes, the heat relay ”RW1" is energized. The “RW1-1”
power contact closes energizing the line voltage draft motor. The
“RW1-2" contact is also closed. As the speed of the draft motor
reaches approximately 2500 RPM, the centrifugal switch contact
located on the end of the draft motor shaft closes to power the first
stage ignition module “IC1”.
After a brief pre-purge time, ignition module “IC1" will start the first
stage ignitor sparking and will open the redundant valve located
inside the first stage main gas valve “GV1” to allow a flow of gas to
only the first stage carryover tube. Only after the pilot flame has
been ignited and the presence of pilot flame detected at the “IC1”
by a signal sent back through the flame sensor is sparking
terminated and the first stage main gas valve opened.
Gas flows into each of the main burners and is ignited from
the carryover tube flame.
If “IC1” fails to detect a pilot flame, it will continue to try for a maximum
of 85 seconds to ignite the pilot tube. If the pilot flame is not detected,
then “IC1" will lock out furnace operation for 5 minutes, then retry
ignition sequence.
section.
CONTINUOUS BLOWER
With the room thermostat switch set to “ON”, the supply air
blower will operate continuously. The normally closed contact
“K5-1" provides 24 volt power to the “3M” contactor. The “3M-1,
2 & 3" power contacts close and the blower motor operates.
INTERMITTENT BLOWER
With the room thermostat system switch set to the “AUTO” or “HEAT”
position and the fan switch set to “AUTO”, the supply air blower will
operate after the room thermostat calls for heat and the time delay
relay closes.
The “TH1" closes, the heat relay ”RW1" is energized. The “RW1-1”
power contact closes energizing the line voltage draft motor. The
“RW1-2" contact is also closed. As the speed of the draft motor
reaches approximately 2500 RPM, the centrifugal switch contact
located on the end of the draft motor shaft closes to power the first
stage ignition module “IC1”.
After a brief pre-purge time, ignition module “IC1" will start the first
stage ignitor sparking and will open the redundant valve located
inside the first stage main gas valve “GV1” to allow a flow of gas to
only the first stage carryover tube. Only after the pilot flame has
been ignited and the presence of pilot flame detected at the “IC1”
by a signal sent back through the flame sensor is sparking
terminated and the first stage main gas valve opened.
Gas flows into each of the main burners and is ignited from
the carryover tube flame.
If “IC1” fails to detect a pilot flame, it will continue to try for a maximum
of 85 seconds to ignite the pilot tube. If the pilot flame is not detected,
then “IC1" will lock out furnace operation for 5 minutes, then retry
ignition sequence.
At the same time power was supplied to the “RW1”, a parallel
circuit activates “ETD” which closes the “ETD” contact after
approximately 35 seconds and energizes “K5" which closes
”K5-2" and starts the blower by energizing “3M”.
When “TH2" closes, heat relay ”RW2" is energized. The
“RW2-1" contact is closed energizing the second stage ignition
module ”IC2". “IC2" will immediately start the second stage
ignitor sparking and will open the redundant valve located
inside the second stage main gas valve ”GV2" to allow a flow
of gas to the second stage carryover tube. Only after the pilot
flame has been ignited and the presence of pilot flame detected
at “IC2" by a signal sent back through the flame sensor is
sparking terminated and the main gas valve opened.
Gas flows into each of the second stage main burners and is
ignited from the carryover tube flame.
If “IC2" fails to detect a pilot flame, it will continue to try for a
maximum of 85 seconds to ignite the pilot tube. If the pilot flame
is not detected, then ”IC2" will lock out furnace operation for 5
minutes, then retry ignition sequence. Note that the second
stage furnace can operate even if first stage has locked out.
When the heating cycle is complete, “TH2" opens de-energizing
the ”RW2" then “TH1" opens de-energizing ”RW1" and “ETD”,
circuit activates “ETD” which closes the “ETD” contact after
approximately 35 seconds and energizes “K5" which closes
”K5-2" and starts the blower by energizing “3M”.
When “TH2" closes, heat relay ”RW2" is energized. The
“RW2-1" contact is closed energizing the second stage ignition
module ”IC2". “IC2" will immediately start the second stage
ignitor sparking and will open the redundant valve located
inside the second stage main gas valve ”GV2" to allow a flow
of gas to the second stage carryover tube. Only after the pilot
flame has been ignited and the presence of pilot flame detected
at “IC2" by a signal sent back through the flame sensor is
sparking terminated and the main gas valve opened.
Gas flows into each of the second stage main burners and is
ignited from the carryover tube flame.
If “IC2" fails to detect a pilot flame, it will continue to try for a
maximum of 85 seconds to ignite the pilot tube. If the pilot flame
is not detected, then ”IC2" will lock out furnace operation for 5
minutes, then retry ignition sequence. Note that the second
stage furnace can operate even if first stage has locked out.
When the heating cycle is complete, “TH2" opens de-energizing
the ”RW2" then “TH1" opens de-energizing ”RW1" and “ETD”,
thus closing all gas valves. The blower motor will continue to
run (approximately 45 seconds after the furnace is shut down)
until “ETD” opens, de-energizing the “K5" relay and ”3M"
contactor. The draft motor will continue to run for a brief
post-purge cycle.
run (approximately 45 seconds after the furnace is shut down)
until “ETD” opens, de-energizing the “K5" relay and ”3M"
contactor. The draft motor will continue to run for a brief
post-purge cycle.
SAFETY CONTROLS
The control circuit includes the following safety controls:
1. Limit Control (LS). This control is located inside the heat exchanger
compartment and is set to open at the temperature indicated in
the Limit Control Setting Table. It resets automatically. The limit
switch operates when a high temperature condition, caused by
inadequate supply air flow occurs, thus shutting down the ignition
control and closing the main gas valves and energizing the blower.
the Limit Control Setting Table. It resets automatically. The limit
switch operates when a high temperature condition, caused by
inadequate supply air flow occurs, thus shutting down the ignition
control and closing the main gas valves and energizing the blower.
2. Centrifugal Switch (CS). If the draft motor should fail, the
centrifugal switch attached to the shaft of the motor prevents
the ignition controls and gas valves from being energized.
the ignition controls and gas valves from being energized.
3. Redundant Gas Valve. There are two separate gas valves
in the furnace. Each valve contains a main and a redundant
valve. The redundant valves are located upstream of the
main gas valves. Should either or both of the main gas
valves fail in the open position the redundant valves serve
as back-ups and shuts off the flow of gas.
valve. The redundant valves are located upstream of the
main gas valves. Should either or both of the main gas
valves fail in the open position the redundant valves serve
as back-ups and shuts off the flow of gas.
4. Flame Sensor Rod / 100% Ignition Control Lock-Out. If an
ignition control fails to detect a signal from the flame sensor
indicating the pilot flame is properly ignited, then the main
gas valve will not open. It will continue to try and ignite the
pilot for a maximum of 85 seconds, then if the pilot flame is
not detected, the ignition control will lock out furnace
operation until 24V power is removed from the module
either at the unit or by resetting the room thermostat.
indicating the pilot flame is properly ignited, then the main
gas valve will not open. It will continue to try and ignite the
pilot for a maximum of 85 seconds, then if the pilot flame is
not detected, the ignition control will lock out furnace
operation until 24V power is removed from the module
either at the unit or by resetting the room thermostat.
5. Rollout Switch. This switch is located above the main burn-
ers in the control compartment which in the event of a
sustained main burner rollout shuts off and locks out both
ignition controls closing both gas valves. The ignition con-
trols lock out furnace operation until 24V power is removed
from the controls either at the unit or by resetting the room
thermostat. Note the auto reset rollout switch must reset
before allowing furnace operation.
sustained main burner rollout shuts off and locks out both
ignition controls closing both gas valves. The ignition con-
trols lock out furnace operation until 24V power is removed
from the controls either at the unit or by resetting the room
thermostat. Note the auto reset rollout switch must reset
before allowing furnace operation.
GAS
VALVE
VALVE
GAS MAIN
MAIN VALVE
TO MAIN
BURNER
BURNER
REDUNDANT
VALVE
VALVE
TO PILOT BURNER
FIG. 12 - GAS VALVE PIPING
HEATER
KW
VOLTAGE
SETTING, AMPS
TH1
TH2
18
208/230-3-60
0.29
-
36
0.29
0.29
54
0.29
0.58
72
0.58
0.58
18
460-3-60
0.29
-
36
0.29
0.29
54
0.29
0.29
72
0.29
0.29
18
575-3-60
0.29
-
36
0.29
0.29
54
0.29
0.29
72
0.29
0.29
TABLE 9 - HEAT ANTICIPATOR SETTING
530.18-N11Y
16
Unitary Products Group