Daikin IM 986-2 VHC Installation & Maintenance Manual

Contents

IM 986-2 / Page 39 of 48Start-upCooling or Heating – Manual OperationAdjust the thermostat heating or cooling setpoint tomaintain desired space temperatureThe MicroTech III unit controller has built-in featuressuch as random start, compressor time delay, nightsetback, load shed, shutdown, condensate overflowprotection, defrost cycle, brownout, and LED/faultoutputs Table 10 shows the LED and fault outputsequences The 24 volt low voltage terminal strip is setso R-G energizes the fan R-W1 energizes the fan andcompressor and reversing valve for heating operationR-Y1 energizes the fan and compressor for coolingmode of operationThe reversing valve is set up to be energized in theheating mode The circuit board has a fan interlockcircuit to energize the fan whenever the compressor isonThe MicroTech III unit controller has a lockout circuitto stop compressor operation if any one of its safetiesopens (high pressure or suction line sensor) If thesuction line low temperature sensor opens, the unit willgo into the cooling mode for 60 seconds to defrost anyslush in the water-to-refrigerant heat exchangerAfter 60 seconds, the compressor is locked out Ifthe condensate sensor detects a filled drain pan, thecompressor operation will be suspended only in thecooling mode The unit is reset by opening and closingthe disconnect switch on the main power supply to theunit in the event the unit compressor operation has beensuspended due to low suction line sensor reaching itsset point, or a high pressure switchThe MicroTech III unit controller has a fault outputsignal to an LED on a wall thermostat Table 10 showsin which function the fault output is “on” (sending asignal to the LED)Units must be checked for water leaks upon initial watersystem start-up. Water leaks may be a result of mishan-dling or damage during shipping. Failure by the installingcontractor to check for leaks upon start-up of the watersystem could result in property damage.CAUTIONIMPORTANTTable 10: LED Fault IndicatorsEach water source heat pump unit has a compressor andblower motor. Each component part has and internaltemperature and amperage sensitive overload. If the over-load opens it will suspend unit operation. Check componentparts by measuring the winding resistance and looking foran open circuit.Additional Accessories – GeneralThermostats and Wall SensorsEasy-to-operate comfort command centers provide acomplete range of deluxe featuresWall-Mounted Programmable ElectronicThermostat (P/N 668810301)1 Heat/1 Cool, Auto Changeover, Hardwired• 7-Day, 5-2-Day 5-1-1 Day Programmable• Configurable• Single-Stage Heat/Cool Systems• Single-Stage Heat Pump Systems• Large Display With Backlight• Selectable Fahrenheit or Celsius• Compatible with Gas, Oil, or Electric• SimpleSet™ Field Programming• Status Indicator Light• Relay Outputs (minimum voltage drop in thermostat)• Remote Sensor Compatible• Ideally Suited for:– Residential (New Construction/Replacement)– Light CommercialLEDs FaultIndication Yellow Green Red OutputNormal Mode Off On Off OffHigh Pressure Fault Off Off Flash OnLow Temperature Fault* Flash Off Off OnCondensate Overflow On Dim Off OnBrownout Off Flash Off OnLoad Shed Off Off On OffUnoccupied Mode On On Off OffUnit Shutdown Off Flash Off On