| 1F90 and 1F97 |
Addendum to | |
| INSTALLATION INSTRUCTIONS |
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FAILURE TO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY BEFORE INSTALLING OR OPERATING THIS CONTROL COULD CAUSE PERSONAL INJURY AND/OR PROPERTY DAMAGE.
If in doubt about whether your wiring is millivolt, line, or low voltage, have it inspected by a qualified heating and air conditioning contractor, electrician, or someone familiar with basic electricity and wiring.
Do not exceed the specification ratings.
All wiring must conform to local and national electrical codes and ordinances.
PRECAUTIONS
!CAUTION
To prevent electrical shock and/or equipment damage, disconnect electric power to system, at main fuse or circuit breaker box, until installa- tion is complete.
Do not short out terminals on gas valve or pri- mary control to test. Short or incorrect wiring will burn out thermostat and could cause personal injury and/or property damage.
WHEN THIS THERMOSTAT IS CONNECTED TO SOME SYSTEMS THAT USE HIGH IMPEDANCE INPUT ELEC- TRONIC MODULES, YOU MAY OBSERVE THE FOL- LOWING CONDITIONS.
1.The furnace fan may turn on when heat has not been called, or may not turn off when thermostat is satisfied and call for heat ends.
2.The furnace may not turn off when thermostat is satisfied and call for heat ends.
3.The air conditioner may not turn off when thermostat is satisfied and call for cool ends.
INSTALLATION
If you observe any or all of these conditions after installing thermostat, you can correct system operation by installing isolation relays between the thermostat and the electronic ignition module. Figures 1 and 2 show how three isolation relays can be installed [one each for the fan (G), heat (W), and cool (Y)]. You may not need to install all three isolation relays to correct the operation conditions.
THERMOSTAT
Red Jumper Wire
RH W | Y | G RC |
Line | 24 VAC |
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Voltage |
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Transformer | Heating | Cooling | Fan | |
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| System | System | Relay |
Figure 1. Wiring for single transformer systems
Figure 1 shows a single transformer heating/cooling sys- tem, with isolation relays installed in the heating (W), cooling (Y), and fan (G) circuits. To simplify the diagram, limit and safety switches are not shown here, although they will be found either in the low or high voltage circuit. Limit and safety switches must be retained. Refer to the equipment manufacturer’s system wiring diagram for the location of limit and safety switches.
!WARNING
DO NOT REMOVE OR WIRE AROUND LIMIT AND SAFETY SWITCHES WHEN INSTALLING ISOLA- TION RELAYS.
| PART NO. | |
| EMERSON ELECTRIC CO. | |
| Printed in U.S.A. | |
| 9797 REAVIS ROAD | |
| 9507 | |
R | ST. LOUIS, MISSOURI |
