Taco PC705-2 Instruction Sheet

Taco PC705-2 Instruction Sheet Manual pdf 1 page image

1 of 12The PC705-2 is a microprocessor-based PID control designed to regulate the supply water tempera-ture to a heating system by controlling a boiler and the speed of an injection pump. The PC705-2controls the system supply water temperature based on the outdoor air temperature (outdoor reset). Aboiler sensor can be connected in order to prevent corrosion in the boiler due to flue gas condensa-tion. If the PC705-2 is controlling the boiler supply water temperature, the control continuously adjuststhe boiler differential in order to optimize the firing cycles of the boiler, prevent large water temperatureswings, and increase the efficiency of the system. A wiring harness is provided to be easily connectedto the Taco Expandable (-EXP) Controls.The PC705-2 also includes features such as an automatic reset ratio calculation, Warm Weather ShutDown (WWSD), and a maximum supply water temperature setting.Control Strategy . . . . . . . . pg. 1 Control Adjustments . . . . . . . . pg. 9Variable Speed Injection . . pg. 3 Display Operation . . . . . . . . . . pg. 10Sequence of Operation . . . pg. 4 Troubleshooting . . . . . . . . . . . pg. 11Installation . . . . . . . . . . . . . pg. 5 Error Messages . . . . . . . . . . . . pg. 12Applications . . . . . . . . . . . . .pg. 6 Settings . . . . . . . . . . . . . . . . . pg. 9OUTDOOR RESETIn order to properly control a hot water heating system, the heat supplied tothe building must equal the heat lost by the building.• The heat supplied to a building is proportional to the temperature of thewater and the surface area of the heating element. A small surface areasuch as baseboard radiators requires a higher water temperature than alarger surface area such as radiant floors.• The heat lost from a building is dependent on the outdoor temperature. Asthe outdoor temperature drops, the building heat loss increases.Instruction SheetPC705-2 Variable Speed Injection Mixing ControlHeatLossIncreasesOutdoorTemperatureDropConstantRoom TemperatureControl StrategyPlant ID#: 9300-1057SUPERSEDES: March 1, 2004 EFFECTIVE: March 2, 2016102-098MixingDemandPC705-2Start 10 30 50 70 90% OutItemC US158033OUTDR°FVIEWInputOutdoor SensorIncludedTo TacoZoneControlInputSupply SensorIncludedItem1H1194APower: 24 V ±10% 50/60 Hz 3 VAVar. Pmp: 120 V (ac) 2.4 A 1/6 hpBoiler: 24 V (ac) 5 A 1/6 hp pilot 240 VAPump: 120 V (ac)2 3OutCom SupSignal wiringmust be ratedat least 300V Made in CanadaPC705-2 C US158033Press & Hold:Item, to view settings, to testPress & Release:Item + + to adjust menu10 30 50 70 90Boil4InputBoiler SensorIncludedDo not apply powerMixingDemandStart% OutOutputVariable SpeedInjection Pump(through back of control)OutputSystem Pumpand/or Boiler Pump(through back of control)VIEWOUTDR°F