Carrier 42 SERIES Application Data

CONTROL SELECTION GUIDEUse this guide to make sure that all necessary components are provided for and that the components are compatiblewith the required control system.NOTE: When thermostatic fan control is selected or when unit outside air dampers are used, unit-mounted thermostatsare not recommended as their use will result in poor room temperature sensing.SYSTEM DESCRIPTION THERMOSTATCHANGEOVERONSUPPLY PIPE VALVE FANSWITCH (SW) NOTES2-PIPE HEATING-COOLING*FanControl(2-Pipe)Fan manually cycled None None None Standard3-Speed SW Not recommendedfor high humidityapplicationThermostat cycles fan on-offfrom speed set withfan switch.Wall mountedincludes heat-coolswitch.None None Thermostat hasintegral3-Speed SWThermostat cycles fan on-offfrom fan speed setwith switch. Modeautomatically switchedby changeoversensing water temp.Wall mounted.Heating/coolingThermostatYes None Standard3-Speed SW Unit mountedthermostats providevery poor roomtemperature controlThermostat cycles fan fromhigh to low on coolingand low to off on heating.Wall or unitmounted Yes None No Standard3-Speed Switch,ON-OFF toggle SWonlyBest fan cyclecontrol forhigh humidityapplicationsTwo-positionelectricvalves(2-pipe)Thermostat cycles valveopen or closed. Wall mountedincludes heat-coolswitch.None Motorized (N.C.)3-way or 2-way,no bypass required.Thermostathas integral3-Speed SWValve packageswith belled end(s)for field solderingto coil.Thermostat cycles valveopen or closed.Mode automaticallyswitched by changeoversensing water temp.Wall or unitmounted.Heating/coolingThermostatYes Motorized (N.C.)3-way or 2-wayStandard3-Speed SW.Others havethermostats withintegral 3-Speed SWPneumaticmodulatingvalves(2-pipe)Thermostat modulatespneumatic control valve.By others. By others. 2- and 3-wayfurnished by others.Can be equippedwith factoryassembledvalve package.Standard3-Speed SWFactory assembledin valve packagew/flare nuts.Valve packageswith belled end(s)for field solderingto coil.ELECTRIC HEATTwo-positionelectricvalve withAuxiliaryElectricHeat(2-pipe)Thermostat cycles valveopen or closed. 2° F aftervalve closes, thermostatactivates electric heater.Heater can’t turn onif hot water is in coil.Wall or unitmounted. Sequencedheating and cooling.Yes.Two Required. Motorized3-way or 2-way Standard3-Speed SWOthers havethermostats withintegral 3-Speed SWValve packageswith belled end(s)for field solderingto coil.Thermostat cycles valveopen or closed. Manualchangeover switchchanges thermostat toheat to activate electricheater.Wall mountedincludes heat-coolswitch.None Motorized3-way or 2-way,no bypass requiredThermostathas integral3-Speed SWValve packageswith belled end(s)for field solderingto coil.Two-positionelectricvalve withtotalelectricheat(2-pipe)Thermostat cycles valveopen or closed.Manual changeover switchchanges thermostat to heatto activate electric heater.Wall mountedincludes heat-coolswitch.None Motorized (N.C.)3-way or 2-way,no bypass requiredThermostathas integral3-Speed SWValve packageswith belled end(s)for field solderingto coil.Thermostat cycles valveopen or closed.2° F after valve closes,thermostat activateselectric heater.Wall or unitmounted.Sequenced heatingand coolingNone Motorized (N.C.)3-way or 2-way,no bypass requiredStandard3-Speed SWPneumaticmodulatingvalves(2-pipe)Thermostat modulatespneumatic control valve.After changeover,thermostatactivates electric heater.By others. By others. 2- and 3-wayfurnished by others.Can be equippedwith factoryassembledvalve package.Standard3-Speed SWFactory assembledin valve packagew/flare nuts.Valve packageswith belled end(s)for field solderingto coil.4-PIPETwo-positionelectricvalves(4-pipe)Thermostat cyclescooling and heatingvalves open or closed.Wall mountedincludes subbasewith heat-coolswitch.None Motorized (N.C.)3-way or 2-way(requires 2 valves)Thermostathas integral3-Speed SWValve packageswith belled end(s)for field solderingto coil.Thermostat cycles coolingvalve open or closed. 2° Fafter valve closes,thermostat cyclesheating valve open or closed.Wall or unitmounted.Sequenced heatingand cooling.None Motorized (N.C.)3-way or 2-way(requires 2 valves)Standard3-Speed SW.Others havethermostatswith integral3-Speed SWPneumaticmodulatingvalves(4-pipe)Thermostat modulatescooling valve.After changeover,thermostat modulatesheating valve.By others. By others. 2- or 3-wayfurnished by others.Can be equippedwith factoryassembledvalve package.Standard3-Speed SWFactory assembledin valve packagew/flare nuts.Valve packagesinclude unions forfor field assemblyto coil.*If system is HEATING-ONLY or COOLING-ONLY, no changeover or bypass is required.NOTE: Unit-mounted thermostats are not recommended with either fan-cycle control or applications with outside air dampers.3