ENVISION SERIES AIR HANDLER INSTALLATION MANUAL
ECM Blower Control
The ECM blower motor is controlled by an interface board installed in the air handler and allows field selectable CFM settings. The interface board receives inputs from the thermostat and converts them to signals used by the ECM motor. There are four different airflow settings that are field selectable via DIP switches (see Blower Performance table).
Cooling/Heating settings
The cooling/heating CFM settings determine the normal cooling/heating CFM when the unit is not in dehumidifica- tion mode or auxiliary heat mode. DIP switches 1 and 2 ‘off’ is the lowest CFM setting while with DIP switches 1 and 2 ‘on’ is the highest CFM setting. To prevent air coil freeze up, the lowest CFM setting can not be used when dehumidifica- tion mode is selected. DIP 9 must be ‘on’ to enable normal airflow settings.
Dehumidification Mode settings
This setting provides for field selection of humidity control (via setting DIP 9 ‘off’). The cooling airflow settings are de- termined by the Cooling/Heating DIP switch settings above. Dehumidification mode reduces the selected normal cooling CFM by
Dehumidification Mode (Continuous) – This mode is se- lected via setting DIP 9 ‘off’ on the ECM interface board and will be engaged whenever an ‘O’ input is present. In this mode any time the unit is operating in cooling mode, it will run at a CFM level
NOTE: Do not select dehumidification mode if the lowest
Cooling/Heating airflow level is selected (DIPS 1 & 2 off).
Auxiliary Heat settings - DIP 5 & 6 on the ECM interface board are used to select the desired CFM in auxiliary/emer- gency heat mode. Whenever auxiliary or emergency elec- tric heat is energized this air flow setting will be used.
15
