Heat Controller MGD-B Series, Руководство пользователя

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Owner’s Manual
MGD-B SERIES GAS FURNACE
Heat Controller, Inc.
G18D Series Gas Furnace OWNER’S MANUAL
Mortex Products Inc. / Fort Worth, TX 76106
G18D Owner’s Manual
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12. After three (3) trials for ignition, if the furnace will
not operate, follow the instructions, “TO TURN OFF
GAS TO APPLIANCE” and call your service
technician or gas supplier.
13. Replace control access panels.
AUTO IGNITION GAS VALVE
TO TURN OFF GAS TO FURNACE
Automatic Ignition Models
1. Set thermostat to the lowest setting.
2. Turn off all electric power to the appliance if service
is to be performed.
3. Remove control access panels.
4. Push the switch on the gas valve to the “OFF”
position. DO NOT FORCE.
5.
Replace control access panels.
SEQUENCE OF OPERATION
Continuous Blower
On cooling / heating thermostats with a AUTO / ON fan
switch, when the fan switch is set to the ON position, 24 VAC
is sent from the red thermostat wire to the green thermostat
wire energizing the blower motor cooling fan terminal (“
G ”
Terminal) on the control board. The control board switches
115 VAC to the
COOL terminal on the control board and the
motor runs on the selected blower motor speed tap.
Intermittent Blower - Cooling
On cooling / heating thermostats with a AUTO / ON fan
switch, when the fan switch is set to the AUTO position and
the thermostat calls for cooling, 24 VAC is sent from the red
thermostat wire to the green thermostat wire and the yellow
thermostat wire. The green thermostat wire will energize the
blower motor cooling fan terminal (“
G” Terminal) on the
control board. The control board switches 115 VAC to the
COOL terminal on the control board and the motor runs on
the selected blower motor speed tap. The yellow thermostat
wire
(“Y”) will send 24 VAC to the contactor on the outdoor
unit causing the contactor to close, energizing the
compressor and the outdoor fan motor.
Intermittent Blower - Heating
On cooling / heating thermostats with an AUTO / ON fan
switch, when the fan switch is set to the AUTO position and
the thermostat calls for heating, 24 VAC is switched from the
red thermostat wire to the white thermostat wire. The
control board has a programmed time delay period that will
place 115 VAC on the
HEAT terminal on the control board at
the completion of the time delay and allow the blower motor
run on the selected blower motor speed tap.
Power ON
When the line power (115 VAC) is turned on to the furnace
the 115 VAC is applied between the
L1 terminal and the
neutral terminal on the control board. The step down
transformer applies 24 VAC to the “
24 VAC ” and the “ COM ”
terminals on the control board. The control board places 24
VAC from the grey wire
on the 9 pin plug, thru the upper limit
control (Manual Reset), thru the blue wire to the main limit
(Auto Reset) and returns 24 VAC signal thru the orange wire
back to the 9 pin plug on the control board. This signal
indicates to the control board software that the limit circuit is
closed. The control board software then checks for a 24 VAC
signal from the pressure switch. If the pressure switch is open
the software checks the flame sensor to determine if a flame
is present. If no flame is present then the software places the
control board into the ready mode which is indicated by a
steady green diagnostic indicator light.
NOTE:
If a limit is open when the line power (115 VAC) is turned on;
the control board software switches 115 VAC to the
HEAT
terminal on the control board sending 115 VAC to the indoor
fan motor energizing the indoor fan on the selected speed
tap and the diagnostic led will flash four flashes.
NOTE:
If the pressure switch electrical contacts are stuck closed
nothing will happen until there is a call for heat. Upon a call
for heat the control board software will wait 30 seconds for
the pressure switch electrical contacts to open. During this
time, none of the components will operate. After 30 seconds
the diagnostic indicator led will flash two flashes and none of
the components will operate.
Heating Cycle
When the thermostat switch is set to the HEAT position, the
thermostat fan switch is set to the AUTO position and the
thermostat calls for heat; 24 VAC is switched from the red
thermostat wire to the white thermostat wire sending a 24
VAC signal to the
“W” terminal on the control board. This
signal tells the control board software there is a call for heat.
The control board switches 115 VAC to the black wires on the
6 pin plug located at the bottom right side of the control
board, energizing the combustion air booster motor.
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