Robur Direct Digital Controller - Page 79

Direct Digital Controller
Direct Digital Controller fw 4.013 – Ed. 01/2013 77
4.4.1.10 Building time constant
The option allows to set the time constant of the building. This is used as a parameter of a filter that has the
purpose of dampening the external temperature variations for the temperature calculations of the water via
climatic curve.
The setting is necessary in the climatic curve and/or external temperature mode is used.
When the external temperature varies, there is a corresponding variation of the heat load and therefore to
keep the temperature constant in the rooms, the water temperature must be modified; this is carried out on the
basis of the climatic curve.
However, due to the heat capacity of the building, the variation of the heat load does not take place instantly
on variation of the external temperature, but progressively in a certain interval of time. It is therefore necessary
to progressively change the water temperature, ideally during the same interval of time.
The value that can be set for the time constant has a range from 0 to 50h with default value of 20h. This must
be set on the basis of the building time constant, e.g. it will assume the low values in the case of pre-fabricated
buildings in wood and high values in the case of traditional buildings in stone.
If the 0 value is set, the filter is disabled. Therefore, for the calculation of the water temperature via climatic
curve the instant value of the external temperature is used, instead of the filtered one.
1 - Select
from the initial screen to gain access to the main menu.
2 - Select
to gain access to the System installation.
3 - Enter the installer password, if requested, on the numerical keypad that appears on the display.
4 - From the drop-down menu select “DDC”.
5 - Select “Building Time Const.” from the drop down menu and press the knob to access the screen.
6 - To modify the data previously set, press the knob and turn it clockwise to increase the value, anti-
clockwise to decrease it.
7 - Press the knob to confirm.
8 - To exit, select
.
4.4.1.11 Reset external temperature filter
This option allows to re-initialise the external temperature filter. The values of the external filtered temperature
are placed equal to that of the instant external temperature and then the filter is re-activated.
NOTE