York SUNLINE DCG Series Installation Manual

Contents

York SUNLINE DCG Series Installation Manual Manual pdf 39 page image

290699-YIM-B-0607Unitary Products Group 39Start the supply air blower motor. Adjust the resis-tances in both the supply and the return air duct sys-tems to balance the air distribution throughout theconditioned space. The job specifications may requirethat this balancing be done by someone other than theequipment installer.To check the supply air CFM after the initial balancinghas been completed:1. Remove the two 5/16” dot plugs from the blowermotor and the filter access panels shown inFigure 15.2. Insert at least 8" of 1/4 inch tubing into each ofthese holes for sufficient penetration into the airflow on both sides of the indoor coil.NOTE: The tubes must be inserted and held in a posi-tion perpendicular to the air flow so that veloc-ity pressure will not affect the static pressurereadings.3. Using an inclined manometer, determine the pres-sure drop across a dry evaporator coil. Since themoisture on an evaporator coil may vary greatly,measuring the pressure drop across a wet coilunder field conditions would be inaccurate. Toassure a dry coil, the compressors should be deac-tivated while the test is being run.4. Knowing the pressure drop across a dry coil, theactual CFM through the unit can be determinedfrom the curve in Pressure Drop vs. Supply AirCFM (Figure 17).After readings have been obtained, remove the tubesand reinstall the two 5/16” dot plugs that were removedin Step 1.NOTE: De-energize the compressors before takingany test measurements to assure a dry indoorcoil.OPERATIONSEQUENCE OF OPERATIONS OVERVIEWFor these units, the thermostat makes a circuitbetween “R” and “Y1” for the cooling cycle.The call is passed to the unit control board (UCB),which then determines whether the requested opera-tion is available and, if so, which components to ener-gize.For gas heating, the UCB monitors the “W1” call butdoes not handle the operation of the gas furnace. Anignition control board controls the gas heater operation.For electric heat units, the UCB passes the call to theelectric heater.In both cases, when the “W1” call is sensed, the indoorair blower is energized following a specified heatingdelay.If at any time a call for both heating and cooling arepresent, the heating operation will be performed. Ifoperating, the cooling system is halted as with a com-pletion of a call for cooling. Heating always takes prior-ity.Failure to properly adjust the total system airquantity and static pressure can result inextensive system damage.FIGURE 17 - PRESSURE DROP ACROSS COIL00.10.20.30.40.50.60.7750 1250 1750 2250 2750 3250 3750036 048072NOMINAL CFMPRESSURE DROP (IWG) 060