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5. 2 zone heating
– mixing valve set up
The ESTIA system has the ability to control the water temperature in 2 zones using different heating
emitters (e.g. zone 1: radiators, zone 2: under floor heating circuits). This is achieved by installing a
mixing valve to control the temperature of zone 2.
The mixing valve position is controlled by comparing the water set point temperature for zone 2
(entered on the ESTIA remote controller) and the actual water temperature in zone 2 (measured by
the TFI sensor). Depending on the result of the comparison between the two temperatures the
mixing valve will either OPEN or CLOSE (in steps) to control the temperature. The hydro unit
software has been designed to drive the valve from CLOSED to OPEN in 12 steps (see the ESTIA
service manual for a detailed description for the mixing valve control).
It is important that the settings for the mixing valve are set correctly using the hydro unit function
codes to achieve accurate temperature control of zone 2.
Connect the mixing valve as shown in the diagram above. The valve connection to
TB04 (in the hydro unit) will depend on whether the valve is an SPST or SPDT type
valve
Set DPSW 12_3 to ON. This enables 2 zone control and will allow the end user to
enter a temperature set point (for zone 2) on the ESTIA remote controller
Set the following function codes:
Set FC1C to the required setting. This will set the maximum target water
temperature of the system when running in heating mode. This setting is
particularly important
– if the heating emitter used is under floor heating
then damage may be caused to the floor surface if FC1A is set too high
Set FC1D to the required setting. This will set the minimum target water
temperature of the system when running in heating mode
Set FC0C. This sets the specified drive time for the mixing valve. The drive
time is the time measured to drive the valve through 90°. The drive time for
the valve will be displayed in the valve specification data. It is important that
this value is set correctly
– this value sets the duration of the mixing valve
drive time for each of the 12 steps.
For example
– if the specified drive time for the valve is 60 seconds then
the drive time for each of the 12 steps will be 5 seconds (60/12 = 5). For
each step of the control power will be applied to the drive valve for a 5
second period.
Setting the value of FC0C bigger or smaller than the actual specified drive
time for the valve will result in poor position control of the mixing valve and
therefore poor temperature control for zone 2
Set FC59 to the required setting. This sets the temperature measuring
period (measured by the TFI sensor) or sampling period between each step
drive of the mixing valve. The value of this function code will depend on a
number of factors (thermal efficiency of the house, type of heating emitters,
size of heating circuits etc.) and so the value set will depend on the
knowledge of the installer / commissioning engineer
