5:12 (16), 0-004-7516-1 (GB)
TAC AB, 1999-08-18
TAC Xenta 102 Handbook
Functional description
TAC Xenta 102-VF
The heating sequence consists of control of the heating coil
combined with a minimum air heating flow, nciMinFlowHeat
(without a fan). A separate PI controller controls the heating
sequence.
Index Variable name
Description
2
nvoUnitStatus
Unit status output
24
nciAppOptions
Application options
30
nciGainHeat
Gain for heating controller
31
nciItimeHeat
Integral time for heating controller
5.3.3 Air quality control
In order to maintain a good air quality TAC Xenta 102
controls the supply of air to the controlled zone. If the carbon
dioxide (CO
2
) sensor indicates a high concentration of CO
2
, the
controller increases the air flow to the controlled zone.
The air flow is proportional to the CO
2
level and is calculated
as a linear function between [nciSpaceCO2Low, nciMinFlow]
and [nciSpaceCO2High, nciMaxFlow].
The air flow is set to the highest value of those coming from the
air quality control and the cooling controller according to
figure 5.5 below.
Air flow
CO
2
level
nciMaxFlow
nciMinFlow
nciSpaceCO2Low
nciSpaceCO2High
Figure 5.5 Air quality control
The air quality control can be enabled independent of the cooling
controller and is enabled in comfort and bypass mode only.
The carbon dioxide concentration can be measured by means of a
permanent carbon dioxide sensor. The controller transforms the
analogue 0–10 V signal into a concentration in ppm by
muliplying it with the variable nciCO2PerVolt (ppm/volt).
Alternatively, you can use a LonTalk carbon dioxide measuring
node connected to the variable nviSpaceCO2. If nviSpaceCO2
has a valid value, the variable has a higher priority than the
electrically connected sensor.