Honeywell T8424C- Manuals

Page 3 - INSTALLATION; When Installing this Product...; CAUTION; Disconnect power supply before beginning wiring; MERCURY NOTICE; UP

T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS 3 68-0180-3 Fig. 1. T8400/T8401 Thermostat dimensions in in. (mm). Fig. 2. T8424 Thermostat dimensions in in. (mm). INSTALLATION When Installing this Product… 1. Read these instructions carefully. Failure to follow them could damage the product or c...

Page 4 - Location; cover plate and wallplate to wall.

T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS 68-0180-3 4 Location Install the thermostat about 5 ft (1.5m ) above the floor in an area with good air circulation at average temperature. See Fig. 3. Do not install the thermostat where it can be affected by:— drafts or dead spots behind doors and...

Page 5 - Wiring

T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS 5 68-0180-3 Fig. 5. Mounting the T8424 wallplate to wall. Wiring IMPORTANT Use an 18-gauge maximum wire for wiring the ther- mostats. All wiring must comply with local electrical codes and ordinances. Disconnect the power supply to prevent electrica...

Page 6 - in single transformer system with

T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS 68-0180-3 6 Fig. 9. T8424 wiring connections. The T8400C Thermostats steal power through the heating and cooling system controls and are adaptable to most 4-wire, 18 to 30 Vac heating-cooling systems. The T8401C and T8424C,D Thermostats are powered ...

Page 7 - directly to vent damper in hydronic intermittent pilot system.

T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS 7 68-0180-3 Fig. 13. T8400C/T8401C heat only wiring diagram for controlling incompatible or 3-wire zone valves or dampers. Heating equipment is operated by end switch on the zone valve or motor, or by thermostat in master zone. Fig. 14. T8400C/T8401...

Page 8 - Mounting Thermostat to Wallplate; SETTINGS AND ADJUSTMENTS; Setting Fan and System Switches; display and system switches.; Fan Switch

T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS 68-0180-3 8 Mounting Thermostat to Wallplate 1. Engage the tabs at the top of the thermostat and wallplate. 2. Swing down the thermostat and press the lower edge of the thermostat onto the wallplate to latch. See Fig. 10. Fig. 15. Mounting T8400 or ...

Page 9 - System Switch; Set Temperature Setpoint; Setting °F/°C Indication and Heat Cycle Rate; Optional System Checkout

T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS 9 68-0180-3 most systems). When using an electric heat thermostat, the fan starts and stops with the heating equipment. Slide the switch in the bottom left corner of the thermostat to select the desired fan setting. System Switch System switch setti...

Page 10 - OPERATION; Zero Droop Performance; System

T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS 68-0180-3 10 10. Press the ▲ key to display the heat cycle rate of 1, 3, 4, 5, 6, 9 or 12. When set at two stages of heat (T8024 only) , both stages operate at selected cycle rate. If the desired cycle is displayed, press the ▲ key to exit the insta...

Page 11 - Energy Savings; Sequence of Operations

T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS 11 68-0180-3 Fig. 19. T8400C power 0stealing internal schematic. Fig. 20. T8401C hardwired internal schematic. Energy Savings You can save energy with the T8400C, T8401C and T8424C,D Thermostats in the heating mode by lowering the temperature settin...

Page 12 - Fan Control; Heat Mode; CHECKOUT; Heating; Fan

T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS 68-0180-3 12 Table 3. Sequence of Operations. a In electric heat models, W and G are energized with calls for heat. b W1 and W2 terminals are energized in the T8424C,D models. Fan Control The FAN switch settings are On and Auto. ON:The fan runs cont...

Page 13 - TROUBLESHOOTING

T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS 13 68-0180-3 TROUBLESHOOTING Refer to Fig. 21 for the proper troubleshooting procedure. Fig. 21. Troubleshooting procedure. SYMPTOM POSSIBLE CAUSE ACTION HEATING OR COOLING EQUIPMENTWON'T OPERATE. NO AC POWER TO THERMOSTAT. • CHECK THAT C TERMINAL I...