Carrier 48VL-E Installation Instructions Manual page 20

48VL-(E, F): Installation Instructions
Normal Operation
An LED (light-emitting diode) indicator is provided on the integrated
gas unit controller (IGC) to monitor operation. The IGC is located by
removing the control access panel (see
operation, the LED is continuously on (See
Airflow and Temperature Rise
The heating section for each size unit is designed and approved for
heating operation within the temperature-rise range stamped on the unit
rating plate.
Table 9 shows the approved temperature rise range for each heating
input, and the air delivery cfm at various temperature rises for a given
external static pressure. The heating operation airflow must produce a
temperature rise that falls within the approved range.
Refer to Indoor Airflow and Airflow Adjustments section to adjust
heating airflow when required.
Heating Sequence of Operation (Ultra Low NOx Single
and Three Phase Models)
(See Fig. 14 - Fig. 17 and unit wiring label)
On a call for heating, terminal W of the thermostat is energized, starting
the induced-draft motor for a 30 second pre-purge at normal ignition
speed. When the pressure switch senses that the induced-draft motor is
moving sufficient combustion air, the burner sequence begins. This
function is controlled by the integrated gas unit controller (IGC).
After 30 sec of pre purge is complete, the pressure switch checks for
sufficient combustion. Then, the gas valve energizes and the system
attempts to ignite with igniter being energized. The igniter energizes for
5 sec and integrated gas controller (IGC) allows system to sense flame
for 2 sec at the end of 5 sec of ignition trial. On first successful ignition,
system stays at the ignittion speed for 10 sec and ramps up to an
intermediate speed for approximately 10 sec and gradually ramps up to
the steady state speed. The system uses the same logic for 2nd and 3rd
ignition trials. In case the 4th attempt fails, the system will lock out for 1
hr. After 1 hr. lock out period, the system starts with normal operating
sequence. Once flame is established and proven successfully, indoor
(evaporator) fan motor is energized after 30 seconds. When the
thermostat is satisfied and W is de-energized, the pre-mix burner will
stop firing and the indoor (evaporator) fan motor shuts off after a 90
second time-off delay. Please note that the IGC has the capability to
automatically decrease the indoor (evaporator) fan motor "ON" delay
and increase the indoor (evaporator) fan motor "OFF" delay in the event
of high duct static and/or partially-clogged filter.
Limit Switches
Normally closed limit switch (LS) completes the control circuit. Should
the leaving-air temperature rise above the maximum allowable
temperature, the limit switch opens and the control circuit "breaks." Any
interruption in the control circuit instantly closes the gas valve and stops
gas flow to the burners. The blower motor continues to run until LS
resets.
When the air temperature at the limit switch drops to the
low-temperature setting of the limit switch, the switch closes and
completes the control circuit. The direct-spark ignition system cycles
and the unit returns to normal heating operation.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Fig. 21). During normal
Table 6 for error codes).
20
Table 6 – LED Indications
Status Code
*
Normal Operation 2
No Power or Hardware Failure
Check fuse, low voltage circuit
Limit Switch Fault
Flame Sense Fault
Four Consecutive Limit Switch Faults
Ignition Lockout Fault
Pressure Switch Fault
Burner Thermal Switch Fault
(Ultra Low NOx models)
Internal Control Fault
Temporary 1 hr auto reset
*. LED indicates acceptable operation. Do not change ignition control board.
†. This code indicates an internal processor fault that will reset itself in one hr.
Fault can be caused by stray RF signals in the structure or nearby. This is a
UL requirement.
NOTES:
1. When W is energized the burners will remain on for a minimum of 60 sec.
2. If more than one error code exists they will be displayed on the LED in
sequence.
Burner Thermal Switch (Ultra Low NOx)
The Burner Thermal Switch (BTS) is used on Ultra Low NOx units and
is located on top of the burner box. (See
functions similar to a rollout switch but also provides protection against
a blocked burner. The BTS switch has the same FAULT CODE (7
flashes) on the ignition board as a rollout switch found on standard Low
NOx units.
Step 3 – Start-up Cooling and Make Adjustments
Complete the required procedures given in the Pre-Start-Up section
before starting the unit. Do not jumper any safety devices when
operating the unit. Do not operate the compressor when the outdoor
temperature is below 40°F (4.4°C) (unless accessory low-ambient kit is
installed). Do not rapid-cycle the compressor. Allow 5 minutes between
on cycles to prevent compressor damage.
Checking Cooling Control Operation
Start and check the unit for proper cooling control operation as follows:
1. Place room thermostat SYSTEM switch in OFF position. Observe
that blower motor starts when FAN switch is placed in ON position
and shuts down when FAN switch is placed in AUTO position.
2. Place SYSTEM switch in COOL position and FAN switch in
AUTO position. Set cooling control below room temperature.
Observe that compressor, condenser fan, and evaporator blower
motors start. Observe that cooling cycle shuts down when control
setting is satisfied. The evaporator fan will continue to run for 60
sec.
3. When using an auto-changeover room thermostat, place both
SYSTEM and FAN switches in AUTO positions. Observe that unit
operates in Heating mode when temperature control is set to call for
heating (above room temperature) and operates in Cooling mode
when temperature control is set to call for cooling (below room
temperature).
IMPORTANT: Three-phase, scroll compressors are direction oriented.
Unit must be checked to ensure proper compressor 3-phase power lead
orientation. If not corrected within 5 minutes, the internal protector will
shut off the compressor. The 3-phase power leads to the unit must be
reversed to correct rotation. When turning backwards, the difference
between compressor suction and discharge pressures will be minimal.
Checking and Adjusting Refrigerant Charge
The refrigerant system is fully charged with Puron (R-410A) refrigerant
and is tested and factory sealed. Allow system to operate a minimum of
15 minutes before checking or adjusting charge.
LED Indication
On
Off
1 Flash
2 Flashes
3 Flashes
4 Flashes
5 Flashes
6 Flashes
7 Flashes
8 Flashes
†
9 Flashes
Fig. 19.) The BTS switch