Carrier 42 SERIES Application Data

Thermostatic Fan Control, 2-Pipe System withSafety Cycle — This control is used for high humiditysituations in which condensate problems can occur if fan isturned off while chilled water is still running through thecoil.The wiring provides fan cycling from HIGH to LOW onthe cooling cycle and from LOW to OFF on the heating cycle.An ON-OFF toggle switch replaces the standard 3-speed fanswitch. The toggle switch can be concealed to ensure thatthe unit runs on low speed when cooling. This action greatlyreduces the chance of condensation problems that exist withother standard fan cycling controls.For control package descriptions, see control componentssection entitled Remote-Mounted Controls and Unit-MountedControls.UNITTYPE LOCATIONPACKAGE CODE*Heating and CoolingPlus ChangeoverVertical Unit Mounted 24-RVerticalorHorizontal Wall Mounted 23-17* Packages listed on current price pages.For NOTES, see below.Thermostatic Electric Valve Control, 2-Pipe —A thermostatically controlled 2-position valve provides su-perior control to fan cycling. With this control, the fan runscontinuously unless it is manually switched to the OFF po-sition. The fan must be on before the valve can be opened tosupply water to the coil.This system can be used for normal 2-pipe changeoversystems and can also be furnished for cooling-only or heating-only applications by omitting the changeover and specifyingwhich application is intended.NOTES:1. Motors are thermally protected.2. Use copper conductors only.3. See unit nameplate for power supply. Provide disconnect meansand overload protection as required.For control package descriptions, see control componentssections entitled Remote-Mounted Controls and Unit-Mounted Controls.UNITTYPE LOCATIONTHERMOSTAT ORWIRING PACKAGE*ELECTRICVALVEHeating orCoolingOnlyHeating andCoolingPlusChangeover†Vertical UnitMounted24-M,24-N 24-L Any 2- or3-way,2-positionvalvepackage.VerticalorHorizontalWallMounted22-C, 22-D,22-E, 22-F 22-A, 22-B*Packages listed on current price pages. First 2 digits are itemnumbers.†For alternate thermostat with manual changeover. Refer to currentprice pages.5