Why is the red LED on my Honeywell CM720 Thermostat relay box illuminated?
The red LED on the relay box illuminates because it's not receiving radio frequency (RF) signals from the room thermostat. This could be due to the thermostat being in a location where the RF signal is blocked, or because the thermostat batteries are dead. Try relocating the room thermostat as per the installation instructions or replace the batteries in the room thermostat.
What to do if my Honeywell CM720 Thermostat relay box doesn't react to setpoint changes?
If the relay box isn't responding to setpoint changes from the room thermostat, it's likely that the thermostat and relay box aren't properly connected. You should reset the relay box by holding the push button for 15 seconds. Then, follow the binding procedure as described in section 5) Additional Installation Information.
What to do if the red LED is on and the green one is flashing after binding Honeywell CM720 Thermostat?
If, after binding, the red LED is on and the green one flashes every 3 seconds on the relay box, it indicates an incorrect or incomplete binding procedure, or the thermostat was incorrectly positioned during binding. Repeat the binding procedure, ensuring the room thermostat is approximately 1 meter away from the relay box.
How to make the Honeywell CM720 relay switch on if it only displays the symbol?
When the room thermostat displays the symbol, it's normal for the relay not to immediately switch on. To activate it, adjust the temperature setpoint by a few degrees using the button. The relay box should then switch on after a short delay.
What to do if the Honeywell CM720 Thermostat relay box does not react to setpoint changes?
If the relay box isn't responding to setpoint changes on the room thermostat, it's likely that the room thermostat and relay box aren't properly bound. Reset the relay box by pressing and holding the push button for 15 seconds, then follow the binding procedure as described in section 5) Additional Installation Information.
What to do if the Honeywell CM720 Thermostat relay box red LED is on and the green one is flashing after binding?
If, after binding, the red LED is on and the green one is flashing once every 3 seconds on the relay box, it indicates an incorrect or incomplete binding procedure, or an incorrect thermostat position during binding. Repeat the binding procedure, keeping approximately 1 meter distance between the relay box and the room thermostat.
How to fix a Honeywell CM720 when the symbol is displayed but the relay doesn't switch on?
If the room thermostat displays the symbol but the relay box relay doesn't switch on, try changing the temperature setpoint by a few degrees using the button. The relay box should switch the relay on after a few seconds delay. Also, this can be normal operation. The relay box cycles the relay on and off for times proportional to the demand signal (0-100%) from the room thermostat. The symbol only indicates that the demand value is greater than 0%.
General| Type | Programmable Thermostat |
|---|---|
| Power Source | Battery |
| Display | LCD |
| Programming | 7-day programmable |
| Programs per day | 4 |
| Voltage | 24V |
| Stages | 1 Heat / 1 Cool |
| Battery Type | AA |
| Compatibility | Heating and Cooling Systems |
| Time Setting | 12/24 hour format |
| Weight | 0.5 lbs |
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