Carrier 30GX Installation, Operation And Maintenance Instructions

Also see for 30GX Series: Installation, operation and maintenance instructions Installation, operation and maintenance instructions

20000810.08 0.088 6.60.18 6.69 0.09 0.099 5.00.19 5.09 5.012 0.012 0.01212 3.00.112 3.0Let us assume that the 0-10 V d.c signalcomes from a calibrated outside temperatureprobe (configuration accessible to CarrierService only) with the followingparameters:• The probe delivers 0 volts at -20°C.• The probe delivers 10 volts at 40°C.Based on this information:• The probe delivers 5.0 volts at 10°C.• The probe delivers 6.6 volts at 20°C.The active cooling setpoint reset curve isthen as follows:Cooling setpoint voltage resetMAXUMUM RESET VALUEBUILDING LOADZERO RESET VOLTAGEMAXIMUM RESET VOLTAGERESE T VALUE% BUILDING LOADVOLTAGE RESET REFERENVE VALUEEQUIVALENT TEMPERATURE REFERENCE VALUEOPERATION PRESS BLOCK 3 BLOCK 1 BLOCK 2KEY LED DISPLAY DISPLAYHold down the MENU button untilthe LED for SETPOINT lights.Press or until block 1displays item number 8; this itemshows the zero reset voltage incooling mode. The default value (0volts) is displayed in block 2.Press the button to authorisemodification of the valueassociated with item 8. TheSETPOINT menu LED flashesindicating that modification modeis active and the value can bemodified.Press the until the value 6.6 isdisplayed in block 2. TheSETPOINT menu LED in block 3keeps flashing.Press the button again tovalidate the change. The new valuefor item 8 is 6.6 volts. TheSETPOINT menu LED stopsflashing, indicating thatmodification mode no longerapplies.Press until block 1 displaysitem number 9; this item shows themaximum reset voltage in coolingmode. The default value (0 volts)is displayed in block 2.Press the button to authorisemodification of the valueassociated with item 9. TheSETPOINT menu LED flashesindicating that modification modeis active and the value can bemodified.Press until the value 5.0 isdisplayed in block 2. TheSETPOINT menu LED in block 3keeps flashing.Press the button again tovalidate the change. The new valuefor item 9 is 5.0 volts. The SET-POINT menu LED stops flashing,indicating that modification modeno longer applies.Press until block 1 displaysitem number 12; this item showsthe maximum reset value incooling mode. The default value(0°C) is displayed in block 2.Press the button to authorisemodification of the value associat-ed with item 12. The SETPOINTmenu LED flashes indicat-ing thatmodification mode is active andthe value can be modified.Press until the value 3.0 isdisplayed in block 2. TheSETPOINT menu LED in block 3keeps flashing.Press the button again to vali-date the change. The new value foritem 12 is 3.0°C. The SETPOINTmenu LED stops flashing, indicat-ing that modification mode nolonger applies.Items 10-11-12 DT reset - Cooling mode reset valuesItems 15-16-17 DT reset - Heating mode reset valuesThis function is only active if an resetbased on water returning to theevaporator (cooling mode) or condenser(heating mode) has been selected (seesection 4.2.10). In the following descrip-tion, ‘DT’ represents the temperaturedifference between water entering andleaving the evaporator in cooling modeor the condenser in heating mode.Since the difference between the leavingwater temperature and the return watertemperature is a measure of the buildingload, a setpoint reset based on the returnwater temperature is actually an resetmethod based on the average buildingload. As the building load falls from100% to 0%, so the entering evaporatorwater temperature falls in proportion tothe load. Thus a drop in temperature inthe evaporator which is in general 5.5°Cat full load would theoretic-ally become0°C at zero load. In this event, the resetparameters are generally configured todeliver an reset with a negative slope:• In cooling mode, the controller automa-tically resets the chilled water setpointupwards in response to a drop in DT.• In heating mode, the controllerautomatically resets the chilled watersetpoint downwards in response to arise in DT.