Using The Room Unit For Specific Applications; Using The Special Features Of The Room Unit - Hitachi SYSTEM MMI PACK Manuel D'installation

Room Unit Installation Guide
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3.3 Using the Room Unit for Specific Applications

The Room Unit is a versatile controller that can be used to control many different applications. Please note
that when the Room Unit is installed in conjunction with a System Controller, the functionality will differ to
that when installed with a standard boiler system. Most of the functions shown below will be controlled by
the System Controller and be set within its parameters. Therefore, some of the system parameters within
the Room Unit menu will not apply. Please also note other changes to the setting of the optimisation and
proportional band settings as shown in tables 3.5.1 and 3.5.2.
NOTE: In order for the Room Unit to send the heating demand signal to the RF Receiver, it is essential
that the Category 2 parameter 8:Su is set to the correct value (see Installer Parameters Table, 3.5.2
Category 2 – System Settings). Failure to do this will mean that the heating system will not respond to
changes in the setpoint on the Room Unit. Under these circumstances the system will operate with no
input from the Room Unit and may not therefore provide adequate temperature control.

3.4 Using the Special Features of the Room Unit

Special Feature: Description:
Heating or Cooling (This feature is not available with the system) This product
Operation 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.
Summer/Winter This feature moves time automatically on the last Sunday
Auto time change of March and the last Sunday of October. The feature is
factory enabled.
Temperature Offset If the Room Unit 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.
Upper/Lower The normal upper temperature limit of 35°C can be
Temperature Limit 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.
50036443-002 B - Hitachi Room Unit Inst (EN, F).indd 8
Enable/Disable
To enable: Set parameter 4:HC
(category 2) to 1.
To enable: Set parameter 3:tC
(category 1) to 1.
Set parameter 12:tO (category
1) to the required offset value.
Set parameter 6:uL (category 1)
to the desired upper limit.
Set parameter 7:LL (category 1)
to the desired lower limit.
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