Carrier 48VT(N) Start-Up, Check for Refrigerant Leaks, Unit Sequence of Operation, 48VT--A

Page 13
FIRE, EXPLOSION HAZARD

e.Ensure wires do not touch refrigerant tubing or sharp sheet metal edges.

f.Inspect coil fins. If damaged during shipping and handling, carefully straighten fins with a fin comb.

!WARNING

FIRE, EXPLOSION HAZARD

Failure to follow this warning could result in personal injury, death or property damage.

Do not purge gas supply into the combustion chamber. Do not use a match or other open flame to check for gas leaks. Use a commercially available soap solution made specifically for the detection of leaks to check all connections.

4. Verify the following conditions:

a.Make sure gas line is free of air. Before lighting the unit for the first time, perform the following with the gas valve in the “OFF” position:

NOTE: If the gas supply pipe was not purged before connecting the unit, it will be full of air. It is recommended that the ground joint union be loosened, and the supply line be allowed to purge until the odor of gas is detected. Never purge gas lines into a combustion chamber. Immediately upon detection of gas odor, retighten the union. Allow 5 minutes to elapse, then light unit.

b.Make sure that condenser-fan blade is correctly positioned in fan orifice. Leading edge of condenser-fan blade should be 1/2 in. (12 mm) maximum from fan orifice.

c.Make sure that air filter(s) is in place.

d.Make sure that condensate drain trap is filled with water to ensure proper drainage.

e.Make sure that all tools and miscellaneous loose parts have been removed.

START-UP

Step 1 — Check for Refrigerant Leaks

Proceed as follows to locate and repair a refrigerant leak and to charge the unit:

1.Locate leak and make sure that refrigerant system pressure has been relieved and reclaimed from both high- and low-pressure ports.

2.Repair leak following Refrigerant Service procedures.

NOTE: Install a bi-flow filter drier whenever the system has been opened for repair.

3.Add a small charge of R-410A refrigerant vapor to system and leak-test unit.

4.Recover refrigerant from refrigerant system and evacuate to 500 microns if no additional leaks are not found.

5.Charge unit with Puron (R-410A) refrigerant, using an electronic scale. Refer to unit rating plate for required charge.

Step 2 — Unit Sequence of Operation

48VT-A Sequence of Operation

a. CONTINUOUS FAN

(1.) Thermostat closes circuit R to G energizing the blower motor for continuous fan.

b. COOLING MODE

(1.) If indoor temperature is above temperature set point thermostat closes circuits R to G, R to Y and R to O-The unit delivers cooling airflow.

c.HEAT PUMP HEATING MODE

Outdoor temperature above balance point setpoint of thermostat.

(1.) On a call for heating, terminals “Y” and “G“ of the Hybrid thermostat are energized. The “Y“ signal is sent to the Defrost Board (DB) terminal “Y”. The DB has a built in five minute anti-short cycle timer which will not allow the compressor to restart before the time delay has expired.

(2.) “T2” energizes the compressor contactor via the High Pressure Switch (HPS) and Low Pressure Switch (LPS). The compressor and outdoor fan start. Thermostat “G” energizes the Interface Fan Board terminal “G”. The blower motor is energized through contacts of the IFB.

(3.) When the thermostat removes the “Y” and “G” calls, the compressor contactor and outdoor fan are de-energized. The evaporator motor is de-ener- gized after a 90 sec. delay.

d.GAS HEATING MODE

Outdoor temperature below balance point setpoint of thermostat.

Heating Sequence of Operation

(See Fig. 15 and 16 and unit wiring label.)

On a call for heating, terminal W of the thermostat is energized, starting the induced-draft motor. When the pressure switch senses that the induced-draft motor is moving sufficient combustion air, the burner sequence begins. This function is performed by the integrated gas unit controller (IGC). The indoor (evaporator)-fan motor is energized 45 sec after flame is established. When the thermostat is satisfied and W is de-energized, the burners stop firing and the indoor (evaporator) fan motor shuts off after a 45-sec time-off delay. Please note that the IGC has the capability to automatically reduce the indoor fan motor on delay and increase the indoor fan motor off delay in the event of high duct static and/or partially-clogged filter.

NOTE: An LED (light-emitting diode) indicator is provided on the control board to monitor operation. The control board is located by removing the burner access panel (see Fig. 19). During normal operation, the LED is continuously on.

Step 3 — Start-up Heating and Make Adjust- ments

!CAUTION

UNIT COMPONENT DAMAGE HAZARD

Failure to follow this caution may result in damage to the unit being installed.

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.

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. Make sure that burner orifices are properly aligned. Unstable operation my occur when the burner orifices in the manifold are misaligned.

Follow the lighting instructions on the heating section operation label (located on the inside of the control access panel) to start the heating section.

NOTE: Make sure that gas supply has been purged, and that all gas piping has been checked for leaks.

48VT-- A

13

Page 12 Page 14
Image 13
Page 12 Page 14
Contents SAFETY CONSIDERATIONS TABLE OF CONTENTSFig. 1 - Unit 48VT-A Installation InstructionsINTRODUCTION RECEIVING AND INSTALLATIONStep 1 - Check Equipment Step 2 - Provide Unit Support48VT--A Fig. 2 - 48VT-A24-30Unit DimensionsA09146 48VT--A Fig. 3 - 48VT-A36-60Unit DimensionsA09147 48VT Fig. 4 - Roof Curb DimensionsSMALL CURB ROOF CURB DETAILStep 5 - Rig and Place Unit ACCESS PANELS MUST BE IN PLACE WHEN RIGGINGInspection Rigging/Lifting of Unit See FigStep 8 - Install Gas Piping Step 7 - Install Flue HoodStep 6 - Connect Condensate Drain Fig. 6 - Condensate TrapConfiguring Units for Downflow Vertical Discharge Step 9 - Install Duct ConnectionsFig. 7 - Sediment Trap FIRE OR EXPLOSION HAZARDFig. 8 - Supply and Return Duct Opening Table 1 - Physical Data - Unit 48VT-A48VT--A Horizontal Duct CoversTable 2 - Maximum Gas Flow Capacity Table 1 - Physical Data - Unit 48VT-ACont’dTable 3 - Heating Inputs 48VT--ASpecial Procedures for 208-VOperation Step 10 - Install Electrical ConnectionsHigh-VoltageConnections Control Voltage ConnectionsPRE-START-UP Balance Point Setting-Thermidistator HybridTransformer Protection ThermostatSTART-UP Step 3 - Start-upHeating and Make Adjust- mentsStep 1 - Check for Refrigerant Leaks Step 2 - Unit Sequence of OperationFig. 11 - Burner Assembly Adjust Gas InputCheck Heating Control Check Gas InputCheck Burner Flame Limit SwitchesNormal Operation Airflow and Temperature RiseRollout Switch Step 4 - Start-upCooling and Make Adjust- mentsChecking and Adjusting Refrigerant Charge Indoor Airflow and Airflow AdjustmentsContinuous Fan Operation Gas Heating Fan Speed Set-upTable 6 - Color Coding for Indoor Fan Motor Leads 48VT--ATable 8 - 48VT-AWet Coil Pressure Drop Fig. 14 - Interface Fan Board IFB48VT--A Table 7 - Filter Pressure Drop Table IN. W.CUNIT 48VT--AHeating 48VT--A1295 48VT--A1445 48VT--A1448 48VT--A48VT A Fig. 15 - 208/230-1-60Wiring Diagram, Unit 48VT-A48VT--A Fig. 16 - 208/230-3-60Wiring Diagram, Unit 48VT-AA09209 48VT--A Fig. 17 - Cooling Charging Table-Subcooling50VT500173 REV A09099Cleaning the Blower Motor and Wheel MAINTENANCEAir Filter Indoor Blower and MotorInduced Draft combustion air Blower Assembly Limit SwitchFig. 18 - Blower Housing and Flue Collector Box Fig. 19 - Unit Access PanelsOutdoor Fan Electrical Controls and WiringRefrigerant Circuit Fig. 20 - Removal of Motor and Blower WheelLoss of Charge Switch Pressure SwitchesHigh-PressureSwitch Gas InputPage LCS - Loss of Charge Switch HPS - High Pressure SwitchFig. 24 - Refrigerant Circuit AccuraterMetering De viceSTART-UPCHECKLIST TROUBLESHOOTINGUNIT OPERATION AND SAFETY HAZARD Synthetic Roof Precautionary Procedure48VT--A PURONR R-410AQUICK REFERENCE GUIDE48VT--A SYMPTOMTable 13 - Troubleshooting Guide-LEDStatus Codes Table 12 - Troubleshooting Guide-Heating48VT--A I. PRELIMINARY INFORMATION MODEL NO Remove and Store in Job FilesTEMPERATURES PRESSURESCatalog No 48VT---05SI 48VT--AEdition Date 04/09 Replaces 48VT---04SI
Top Page Image Contents