Honeywell CM921 User Manual page 14

Symptom
The thermostat's LCD display
works but the heating does not
switch on (HC60NG LEDs are off
or green one is on).
The red LED on the HC60NG is
constantly on or lashing.
Heating switches ON or OFF too
slowly or quickly.
Temperature swings between
too hot and too cold.
Possible Cause
No power to heating system.
Program does not call for
heat.
Wrong electrical connection.
RF communication lost due
to the wrong location of the
thermostat.
RF communication fault.
The thermostat not set
correctly for your system.
The thermostat not set
correctly for your system.
Remedy
Check that there is power to the heating system.
Move the slider switch to MAN and press
increase the temperature a few degrees above the
current room temperature. The heating should come
on after a few seconds.
Call electrical installer to check the boiler and
HC60NG power supply as well as the connection
between the boiler and the HC60NG.
Hook the thermostat back on the wall bracket or
replace the thermostat on the table stand in the
position where RF communication was reliable.
Call installer.
NOTE: You can control the boiler manually when the RF
communication is lost: Press the HC60NG push button
to switch the boiler on and off. When the green LED is
on – the boiler is on.
Call Installer.
Call Installer.
or to