Master/Relay (relay reading ER1)
When setting up a large installation and connecting two or more thermostats as Master and Relays, all devices MUST have a floor sensor hooked up. An ER1 code would indicate that one of the units does not have a sensor connected. Because the relay units will follow the Master signals, it is ok to install a “dummy sensor” to the back of the unit and leave it hanging in the wall. However, you would not be able to run a separate floor temperature for that zone later on.