Issue
Xenta 102-AX Pressure Dependent Settings for heating mode
Product Line
TAC Vista
Environment
Xenta 102-AX
Cause
A Xenta 102-AX controller set to Pressure Dependent mode will use the minimum heating flow setpoint (SCPTminFlowHeat) to determine the maximum damper position in heat mode. This parameter defaults to 50% of the cooling maximum, which will limit the damper to values of 50% or below in heat mode.
Resolution
The maximum damper position in heat mode for a Pressure Dependent Xenta 102-AX is defined by the following formula:
(Minimum Heating Airflow / Cooling High Flow) x 100%
For a Xenta 102-AX configured with 1-stage discrete auxiliary heat and the HAF set to 50% of the CHF, the unit will operate according to the following sequence:
- Temperature drops, Terminal Load falls to -50%, Damper opens by the same percentage as terminal load up to 50% and stops.
- Heat 1 also tracks Terminal Load and when it reaches 90% (when terminal load falls to -90%), Auxiliary Heat 1 enables.
- Temperature rises, Terminal Load rises to -50%, Damper starts to close, and Auxiliary Heat 1 stays enabled.
- Terminal Load rises to -10%, Damper closes to 10%, Auxiliary Heat 1 disables.