Thermostatic Valve Control, 4-Pipe — The 4-pipe system provides the ultimate in economy and room temperature con- trol. Both hot water and chilled water are available at any time.
Normally an automatic changeover thermostat is used, but a manual changeover thermostat is also suitable. Two 2-way valves, two 3-way valves, or one 2-way plus one 3-way valve must be selected. An automatic changeover device to sense water temperature is not required.
With this system, the fan runs continuously unless it is manually switched to OFF position. Fan must be on before thermostat can send signal to open the chilled water or hot water valve.
NOTE: Wiring diagrams are for 120-v power supply. If other voltages for heaters or controls are specified, wiring may differ from that shown. See Fig. 65 and 66 for line voltage control. See Fig. 67 and 68 for 24-v control.
a42-4079 |
Δ120-V WHT ALL OTHERS BLK |
NEC CLASS 1 WIRING |
Fig. 65 — 42SG,SH,SJ,VA,VB,VC,VE,VF 4-Pipe Heating and Cooling —
Unit-Mounted Thermostat (Line Voltage)
