Bard GV27S1-A Installation Instructions Manual - page 24
Manual 2100-510E
Page
24 of 38
SEQUENCE OF OPERATION
BLOWER
Blower functions are all automatic through the thermostat
control. (See Table 1 for the specific airflows on each
speed.) Motor control inputs are all 24 VAC with line
power to motor being continuous.
On a call for “G” from the thermostat (
call for manual fan
),
speed tap #1 on the blower motor is energized.
On a call for “Y1” from the thermostat (heating or
cooling), speed tap #2 of the blower motor is energized
immediately. Simultaneously, the “Y1” tap of the blower
control board is also energized, and following 5 minutes,
the blower control will power speed tap #3 of the blower
motor.
On a call for “Y2” operation from the thermostat (heating
or cooling), speed tap #5 will be energized through the
blower control board.
The exception is a jumper pin
connection on the blower control board. It comes from the
factory by default jumpering Pins #4 and #5 together to
run the blower at nominal rated full load airflow. If this is
too noisey, this jumper can be removed from Pins #4/#5 to
allow the full load airflow to be reduced by 10% (see Unit
Wiring Diagram).
On any call for “W” (electric heat operation), from the
thermostat, speed tap #5 is always energized. (It is not
affected by the #4/#5 jumper on the blower control board.)
PART LOAD COOLING
When thermostat system switch is placed in COOL, it
completes a circuit from “R” to “O”, energizing the
reversing valve solenoid. On a call for cooling, the
thermostat completes a circuit from “R” to “Y1”, which
energizes the compressor contactor and blower motor on
speed tap #2 initially, then speed tap #3 after 5 minutes
(see BLOWER above).
FULL LOAD COOLING
The system should already be in Part Load Cooling
operation prior to Full Load Cooling being energized.
Additionally what happens, the thermostat completes a
circuit from “R” to “Y2”. This sends a signal to both the
staging solenoid on the side of the compressor and
energizes either tap #5 (or tap #4) of the blower motor (see
BLOWER above).
PART LOAD HEATING (No Electric Heat)
When thermostat system switch is placed in HEAT, the
reversing valve solenoid is no longer energized. On a call
for part load heating, the thermostat completes a circuit
from “R” to “Y1”, which energizes the compressor
contactor and blower motor on speed tap #2 initially, then
speed tap #3 after 5 minutes (see BLOWER above).
FULL LOAD HEATING (No Electric Heat)
The system should already be in Part Load Heating
operation prior to Full Load Heating being energized.
Additionally what happens, the thermostat completes a
circuit from “R” to “Y2”. This sends a signal to both the
staging solenoid on the side of the compressor and
energizes either tap #5 or tap #4 of the blower motor (see
BLOWER above).
SUPPLEMENTARY ELECTRIC HEAT
The system should already be in FULL LOAD HEATING
operation (above). The thermostat completes a circuit from
“R” to “W2”, which energizes up to 9 KW of electric heat
(depends on heater package installed). 9 KW of electric
heat is the limit when operating with the heat pump and is
controlled through the emergency heat relay.
EMERGENCY HEAT MODE
When thermostat system switch is placed in EMERGENCY
HEAT MODE and the thermostat calls for heat, it
completes a circuit from “R” to “E” and from “R” to “W2”.
This will energize the heater package for all available KW
per the installed heater package. (
The call from “R” to
“E” locks out compressor operation.
) The blower motor is
automatically energized with this function and will run on
speed #5 (see BLOWER above).