IOM - Johnson Controls Inc.

FORM 145.19-IOM1 (908)20. SEQUENCE OF OPERATION ONCOOLING CYCLE – VPP UNITS ONLY1 . Room thermostat calls for cooling, connecting Rto Y and O terminals (Reversing valve energizedonly in cooling).2 . The compressor and outdoor fan start immediatelyon a call for cooling. Air circulating fan also startsimmediately with cooling operation.3 . When the room thermostat is satisfied, terminalsY and O on the thermostat are de-energized.4 . The compressor, outdoor fan and indoor fan stopimmediately when the thermostat is satisfied. Thereversing valve returns to the default position.5 . A compressor restart delay timer is activated atthe end of each cooling cycle. A minimum delaytime of 3 minutes is required to ensure that systempressures have equalized before a compressorrestart.21. SEQUENCE OF OPERATION ON HEATINGCYCLE – VPP UNITS ONLYA. OUTDOOR AMBIENT ABOVE 40°F1. Room thermostat calls for heat, connecting R andY terminals (O terminal de-energized).2. The compressor and outdoor fan start immediatelyon a call for heating. Air circulating fan also startsimmediately with heating operation.3. When the room thermostat is satisfied, terminal Yon the thermostat is de-energized.4. The compressor, outdoor fan and indoor fan stopimmediately when the thermostat is satisfied.5. A compressor restart delay timer is activated atthe end of each cooling cycle. A minimum delaytime of 3 minutes is required to ensure that systempressures have equalized before a compressorrestart.B. OUTDOOR AMBIENT BELOW 40°F1 . Room thermostat calls for heat, connecting R andY terminals (O terminal de-energized).2 . The normally closed contacts of the Low Ambientrelay (R2) route the thermostat signal throughR3 to energize the electric element switchingsequencers.The heat/cool interlock relay (R3) preventsthe electric heat from being energizedthrough terminal Y of a singlestageheat pump thermostat.3 . On 2kW through 5kW models the electrical heateris energized between 1-24 seconds after timedelay is energized. Indoor fan is interlocked simultaneouslywith heating element operation.4 . On a unit with two heating elements (6kW, 8kW,or 10 kW), the 2nd element will be energizedapproximately 90 seconds after the first stage isenergized.5 . When the room thermostat is satisfied, terminalsR and Y on the thermostat open, de-energizing the1S/2S sequencer relays.6 . The bank of heating elements will be disconnectedin descending order, the indoor fan will continue torun until the elements are deenergized.22. UNIT SECTION START-UP CHECKLISTBefore starting unit for the first time, be sure youcan answer “Yes” to each of these questions:1 . Is the unit level?2 . Have you cleared away all loose construction andinsulation materials?3 . Is unit installed within proper clearances to combustiblematerials?4 . Does electrical wiring follow current NationalElectrical Code ANSI 70 or CSA C22.1 as well aslocal codes?5 . Is unit electrically grounded?6 . Is room thermostat properly installed?7 . Is duct work system correctly sized and sealed?8 . Are air filters in place and correctly sized?23. SYSTEM BALANCEElectric heating elements require a minimumairflow to ensure proper heatingoutput and maximum element operatinglife. Low airflow will also cause poorcooling performance.Blower speed taps are factory set for optimumheating and cooling airflow ranges. Refer to Table1 for factory blower speed settings, and minimumallowable heating airflow.Operating unit below the minimumheating airflow may cause poor heatingperformance and decreased resistantheater life.16JOHNSON CONTROLS