Table of Contents
Advertisement
D
C
EFROST
YCLE
NOTE: The defrost board is equipped with a jumper for SmartShift™ defrost technology operation. This operation turns the
compressor off for 30 seconds at defrost initiation and termination. The unit is factory shipped for SmartShift™ defrost technology
operation. To operate unit at rated efficiencies, move the jumper on the defrost board from "DLY" to "NORM".
During operation the power to the circuit board is controlled by a temperature sensor, which is clamped to a feeder tube entering
the outdoor coil. Defrost timing periods of 30, 60 and 90 minutes may be selected by setting the circuit board jumper to 30, 60 and
90 respectively.
Accumulation of time for the timing period selected starts when the sensor closes (approximately 34°F), and when the wall
thermostat calls for heat. At the end of the timing period, the unit's defrost cycle will be initiated provided the sensor remains
closed.
Upon a call for defrost, the blower will continue to run and the defrost board will send a W1 signal to the ignition control. At the
same time the compressor will stop for 30 seconds, if the SmartShift™ defrost technology delay feature is selected on the defrost
board. At this time, the reversing valve shifts from heat to cool position and condenser fans shut off. The inducer motor will
immediately energize for a 15 second prepurge.
A 7-second trial for ignition begins by energizing the low and high stages of the gas valve along with this spark ignition. Main burners
light and control detects presence of flame. The compressor (after its 30/OFF second delay) restarts in cooling mode to defrost the
condensor coil.
When the sensor opens (approximately 60°F), the defrost cycle is terminated and the timing period is reset. If the defrost cycle is
not terminated due to the sensor temperature, a twelve minute override interrupts the unit's defrost period. At this time the W1
signal is removed from the ignition control board, the compressor will stop for a 30 second SmartShift™ defrost technology delay (if
selected) and the reversing valve slides back to its normal heat position.
C
OOLING
1. Thermostat calls for cooling.
2. When the thermostat call is for cooling, the compressor and outdoor fan are energized .
3. The indoor blower will energize approximately 6 seconds later.
4. The unit delivers cooling to the conditioned space until the thermostat is satisfied.
5. The compressor and outdoor fan will be de-energized when the thermostat opens.
6. The indoor blower continues to run at low cool speed for approximately 60 seconds after the thermostat is satisfied. This
allows additional cooling from the indoor coil to be transferred to the conditioned space. Then, the indoor blower is de-
energized.
NOTE: A 180-second anti-short cycle is integral to the control and prevents recycling of the compressor.
Cooling Operation
NOTE: Mechanical cooling cannot be reliably provided at ambient temperatures below 50° F.
1. Turn on the electrical power supply to the unit.
2. Place the room thermostat selector switch in the COOL position (or AUTO if available, and if automatic changeover from
cooling to heating is desired).
3. Set the room thermostat to the desired temperature.
F
O
AN
NLY
1. Thermostat calls for FAN ONLY by energizing "G".
2. The indoor blower is immediately energized at the low heat speed.
3. The indoor blower is immediately de-energized once thermostat call for FAN is removed.
A
M
IR FLOW
EASUREMENT AND
Please review the Duct Work section before proceeding with the airflow measurements and adjustments in this section.
Unit blower curves (see Specification Sheets) are based on external static pressure (ESP per in/W.C.). The duct openings on the
unit are considered internal static pressure. As long as ESP is maintained, the unit will deliver the proper air up to the maximum
static pressure listed for the CFM required by the application (i.e. home, building, etc.)
In general, 400 CFM per ton of cooling capacity is a rule of thumb. Some applications depending on the sensible and latent capacity
requirements may need only 350 CFM or up to 425 CFM per ton. Check condition space load requirements (from load calculations)
and equipment expanded ratings data to match CFM and capacity.
After unit is set and duct work completed, verify the ESP with a 1-inch inclined manometer with pilot tubes or a Magnahelic gauge
and confirm CFM to blower curves in the Specification Sheets.
NOTE: Never run CFM below 350 CFM per ton, evaporator freezing or poor unit performance is possible.
A
F
A
F
IR
LOW
DJUSTMENTS
OR
EEM Motor
Adjust the CFM by changing the 24V low voltage lead at the speed terminal block on the motor. (T1, T2, T3, T4, T5). See Blower
Performance Data in the appendix for airflow delivered at each speed tap.
NOTE: Factory set T1 (G, fan and low stage gas heat), T2 (high stage gas heat, T4 (nominal heat pump / cooling).
T3 is for optional low speed cooling and heat pump. T5 is for optional high speed cooling and heat pump.
A
DJUSTMENT
I
B
M
NDOOR
LOWER
OTOR
15
Advertisement
Table of Contents
