Sequence Of Operation; Cooling Mode; Heating Mode; Refrigerant Lines - Bosch Greensource SM024 Installation, Operation And Maintenance Manual

SM AH Series Heat Pump
Just above and to the right of the thermostat
connection block are four sets of jumper pins
labeled ADJ, DELAY, HEAT and COOL. The ADJ set
of pins are labeled NORM, (+), (-) and TEST. AP
units will all be set on the NORM position from the
factory, however, airflow can be increased (+) or
decreased (-) by 15% from the pre-programmed
setting by relocating the jumper in this section.
The TEST position is used to verify proper motor
operation. If a motor problem is suspected, move
the ADJ jumper to the TEST position and energize
G on the thermostat connection block. If the motor
ramps up to 100% power, then the motor itself is
functioning normally. Always remember to replace
the jumper to NORM, (+) or (-) after testing and
reset the unit thermostat to restore normal
operation.
Do not set the ADJ jumper to the (-) setting when
electric heaters are installed. Doing so may cause
the heaters to cycle on their thermal overload
switches, potentially shortening the life of the
switches.
The other three sets of jumper pins are used to
select the proper program in the ECM motor for
the unit. Refer to Figure #7 for the proper jumper
placement.
To the left of the red and green status LED's is a
row of 1/4" male quick connects. These are used
to pass thermostat inputs on to the rest of the
control circuit. Remember to always turn off unit
power at the circuit breaker before attaching or
disconnecting any wiring from these connections
to avoid accidental short circuits that can damage
unit control components.

SEQUENCE OF OPERATION

Cooling Mode

See Typical Wiring Diagram at the end of the
manual. Energizing the "O" terminal energizes the
unit reversing valve in the cooling mode. The fan
motor starts when the "G" terminal is energized.
When the thermostat calls for cooling (Y), the loop
pump or solenoid valve if present is energized and
compressor will start.
Once the thermostat is satisfied, the compressor
shuts down accordingly and the fan ramps down to
either fan only mode or off over a span of 30 seconds
(ECM Motors).
Note that a fault condition initiating a lockout will
de-energize the compressor.

Heating Mode

Heating operates in the same manner as cooling,
but with the reversing valve de-energized. The
compressor will run until the desired setpoint
temperature on the thermostat is achieved.
Once the thermostat is satisfied, the compressor
shuts down and the fan ramps down in either fan
only mode or turns off over a span of 30 seconds.
Auxiliary electric heating coils are not available on
the EP product line.

REFRIGERANT LINES

The installation of the copper refrigerant tubing
must be done with care to obtain reliable, trouble-
free operation. This installation should only be
performed by qualified refrigeration service and
installation personnel.
Refrigerant lines generally can and should be
routed and supported so as to prevent the
transmission of vibrations into the building
structure. Experience and good design practice
dictate 75 feet as the maximum practical length for
interconnecting refrigerant lines in split system
heat pumps without special considerations.
Beyond 75 feet, system losses become substantial
and the total refrigerant charge required can
compromise the reliability and design life of the
equipment.
Refrigerant lines should be sized in accordance
with Figure #13 in the following instructions.
Copper tubing should be clean and free of
moisture and dirt or debris. The suction and liquid
lines MUST be insulated with at least 3/8" wall,
closed-cell foam rubber insulation or the
equivalent.
Some points to consider are:
• Pressure drop (friction losses) in refrigerant
suction lines reduces system capacity and
increases power consumption by as much as
2% or more, depending on the line length,
number of bends, etc. Pressure drop in liquid
lines affects system performance to a lesser
degree, provided that a solid column of liquid
(no flash gas) is being delivered to the
refrigerant metering device, and that the liquid
pressure at the refrigerant metering device is
sufficient to produce the required refrigerant
flow.
Sequence of operation | 11
8733920846 (2014/01)