Daikin DCG Series Installation And Maintenance Manual

Also see for DCG Series: Service instructions Installation instructions Installation instructions

14Utilization Voltage - The voltage of the line terminals of the equip-ment at which the equipment must give fully satisfactory perfor-mance. Once it is established that supply voltage will be main-tained within the utilization range under all system conditions,check and calculate if an unbalanced condition exists betweenphases. Calculate percent voltage unbalance as follows:Three Phase Models3) PERCENT VOLTAGEUNBALANCE2) MAXIMUM VOLTAGE DEVIATIONSFROM AVERAGE VOLTAGE1) AVERAGE VOLTAGEHOW TO USE THE FORMULA:EXAMPLE: With voltage of 220, 216, and 2131) Average Voltage = 220+216+213=649 / 3 = 2162) Maximum Voltage Deviations from Average Voltage = 220 - 216 = 43) Percent Voltage Unbalance = 100 x = = 1.8%Percent voltage unbalance MUST NOT exceed 2% .4216400216= 100 XCONTROL V OLTAGE C HECKWith disconnect switch in the open “OFF” position, disconnectblue wire from low voltage transformer TRANS1. Close the discon-nect switch to energize TRANS1 control transformer. Check pri-mary and secondary (24V) of control transformer TRANS1.AIR FLOW ADJUSTMENTSNOTE: For 2 Speed Models, airflow adjustments must be made onhigh speed, i.e., 2nd stage cooling or in heat mode.The drive on the supply fan is typically set in the middle of theRPM range. The drive motor sheave pitch diameter is field adjust-able for the required airflow. Refer to the following “DriveAdjustments” section.When the final adjustments are complete, the current draw of themotor should be checked and compared to the full load currentrating of the motor. The amperage must not exceed the servicefactor stamped on the motor nameplate. The total airflow mustnot be less than that required for operation of the electric heatersor the furnace.If an economizer is installed, check the unit operating balance withthe economizer at full outside air and at minimum outside air. Uponcompletion of the air flow balancing, we recommend replacingthe variable pitched motor sheave with a properly-sized fixedsheave. A matching fixed sheave will provide longer belt and bear-ing life and vibration free operation. Initially, it is best to have avariable pitched motor sheave for the purpose of airflow balanc-ing, but once the balance has been achieved, fixed sheaves main-tain alignment and minimize vibration more effectively. For directdrive units, move green wire for fan.NOTE: On “non-two speed models” (two-speed models have a “V”in the eleventh character of the model number), never run CFMbelow 300 CFM per ton. Evaporator freezing or poor unit perfor-mance is possible.EVAPORATOR FAN R OTATION C HECKCheck that fan rotates clockwise when viewed from the drive sideof unit and in accordance with rotation arrow shown on blowerhousing. If it does not, reverse any two incoming power cables atSingle Point Power Block. In this case, repeat bearing check.Do not attempt to change load side wiring. Internal wiring assuresall motors and compressors will rotate in correct direction onceevaporator fan motor rotation check has been made.ELECTRICAL INPUT C HECKMake preliminary check of evaporator fan ampere draw and verifythat motor nameplate amps are not exceeded. A final check ofamp draw should be made upon completion of air balancing ofthe duct system (see Appendix C).S ET E VAPORATOR F AN R PMActual RPM’s must be set and verified with a tachometer or strobelight. Refer to Appendices A and B for basic unit fan RPM. Referalso to “Airflow” section of this manual. With disconnect switchopen, disconnect thermostat wires from terminals Y and W. Thiswill prevent heating and mechanical cooling from coming on. Placea jumper wire across terminals R and G at TB1 terminal block. Closedisconnect switch; evaporator fan motor will operate so RPM canbe checked.For gas heat units, the airflow must be adjusted so that the airtemperature rise falls within the ranges given stated on Data Plate(see Appendix A - Blower Performance).BELT DRIVE MODELS ONLYThe drive on the supply fan is typically set in the middle of theRPM range. The drive motor sheave pitch diameter is field adjust-able for the required airflow. Refer to “Motor Sheave Adjustmens”section.Upon completion of the air flow balancing, we recommend re-placing the variable pitched motor sheave with a properly-sizedfixed sheave. A matching fixed sheave will provide longer belt andbearing life and vibration free operation. Initially, it is best to havea variable pitched motor sheave for the purpose of airflow balanc-ing, but once the balance has been achieved, fixed sheaves main-tain alignment and minimize vibration more effectively. For directdrive units, move fan speed wire.B EARING C HECKPrior to energizing any fans, check and make sure that all setscrewsare tight so that bearings are properly secured to shafts.T ENSION AND ALIGNMENT A DJUSTMENTCorrect belt tension is very important to the life of your belt. Tooloose a belt will shorten its life; too tight, premature motor andbearing failure will occur. Check you belt drive for adequate “run-in” belt tension by measuring the force required to deflect thebelt at the midpoint of the span length. Belt tension force can bemeasured using a belt tension gauge, available through most beltdrive manufacturers.