Honeywell Thermostat CM900 User Manual download pdf (Page 6)

6 CM900 Wireless - Programmable Room Thermostat

3.1 Automatic Operation

The Relay Box receives the heat demand (0-

100%) signal from the room thermostat. The

room thermostat will display the symbol on the

LCD display whenever more heat is required.

Depending on the demand the Relay Box will

switch the heating device on to match the current

requirements of the system.

The green LED indicates the status of the relay

output:

• GreenLEDon=relayon

• GreenLEDoff=relayoff

3.2 Temporary Manual Override

Pressing the Relay Box button will override the current relay position. As soon as the next signal is received

from the room thermostat the Relay Box will return back to automatic operation as the automatic control

has higher priority than manual operation.

3.3 Communications Loss

If the RF communication is lost for a period of 1 hour the red LED will illuminate to indicate that no RF

messages have been received during the last hour.

The Relay Box will also enter the failsafe mode as selected in Installer Mode (see section 4.2 BDR91

Relay Box Fail-Safe Mode Setup). To allow manual control of the Relay Box output manual override is

available in fail-safe mode. When RF communication is restored the Relay Box will automatically return to

normal operation.

You can now use the USER GUIDE supplied with the room thermostat to demonstrate how it works to the

home owner.

3) Basic Operation of the System

4) Installer Mode

Installer Mode is used to alter the system settings for speciﬁc applications, to use the special features of

the room thermostat in a different way or to alter the factory preset parameters. Parameters are divided

into two groups:

- Category 1 parameters – Room Thermostat Setup

- Category 2 parameters – System Setup.

These are all listed in section 4.5 Installer Parameters Table.

BDR91 Relay Box

Push button and

relay status LED’s

1 2 3 4 5 6 7 8 9 10 11 12

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Honeywell Thermostat CM900 User Manual Page 6