Installer parameter tables – Honeywell cm921 User Manual

Page 4

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CM921 CHRONOTHERM

4
EN0H 8557 UK07 R0 09/06

Special Features

Description

Setting

Optimisation
(Variable Start
Time)

The thermostat will adjust the start time in the morning/afternoon
so the desired temperature is reached by the start of the program
period. The system will restrict the start time to a max of 2 hours.

To enable: Set parameter 8:OP
(category 1) to 1.

Heating or Cooling
Operation

This product can be used for heating or cooling applications. If
you select cooling mode the control algorithm and factory default
program will be modified. You can independently modify the
heating and cooling profile.

To enable: Set parameter 4:HC
(category 2) to 1.

Summer/Winter
Auto time change

This feature moves time automatically on the last Sunday of
March and the last Sunday of October. The feature is factory
enabled.

To enable: Set parameter 3:tC
(category 1) to 1.

Temperature Offset

If the thermostat is located in a particularly hot/cold location for
reliable signal transmission reasons then the measured/displayed
temperature can be adjusted by +/- 3°C. This is useful if the
homeowner wants the reading to match another appliance
temperature display.

Set parameter 12:tO (category
1) to the required
offset value.

Upper/Lower
Temperature Limit

The normal upper temperature limit of 35°C can be reduced to
21°C to save the homeowner energy. The normal lower limit of
5°C can be increased up to 21°C to protect inhabitants from cold.

Set parameter 6:uL (category 1)
to the desired upper limit.
Set parameter 7:LL (category 1)

Parameter

Installer Set-
Up Number /
Abbreviation
(Press + or -
keys to
select)

Factory Setting

Optional Setting

Category 1 Parameters – Room Thermostat Settings

Display

Description

Display

Description

AM-PM / 24hr Display

1:Cl

24

24 hr clock display

12

12 hr AM / PM clock display

RESET Time /
Temperature Program

2:rP

1

Time / Temperature profile set
to factory default
Changes to 0 when one of the
time/temp profiles are changed

0

1

Time / Temperature are as programmed

To restore the factory profile set to 1

Automatic
Summer/Winter Time
Change

3:tC 1

Automatic

Summer/Winter

Time Change Enabled

0

Automatic Summer/Winter Time Change
Disabled

LCD Backlighting

5:bL

1

Backlighting Enabled

0

Backlighting Disabled

Upper Temperature
Limit

6:uL

35

35°C Upper Temp. Limit

21 to 34

21°C to 34°C adjustment in 1°C steps

Lower Temperature
Limit

7:LL

5

5°C Lower Temp. Limit

6 to 21

6°C to 21°C adjustment in 1°C steps

Optimisation

8:0P

0

Optimisation disabled

1

Optimisation enabled

Temperature Offset

12:tO

0

No offset

-3 to +3

-3°C to +3°C adjustment in 0.1°C steps

Proportional Band
Width

13:Pb

1.5

1.5°C Proportional Band

1.6 to 3.0

1.6°C to 3.0°C adjustment in 0.1°C steps

Reset Parameters to
Factory Defaults

19:FS

1

All settings held are the factory
defaults.

Changes to 0 when one of the
parameter values are changed

0

1

Settings are as modified above

To restore the factory profile set to 1

INSTALLER PARAMETER TABLES

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