ENVI
®
Control
17
1.6.2.6 CH Mode 5 (Header & ODA & Stat)
Two sensors are required to sense header temperature and outdoor temperature. A list of accessory choices for
different applications is shown in section 1.0 on page 3.
Description
This mode is a combination of CH Mode 1 (ODA & Stat) and CH Mode 4 (Header & Stat). When the boiler is enabled
through TB1/LV terminals 1 and 2, the setpoint temperature is maintained at the location of the header sensor based
on the ODA reset schedule that is determined from the optional outdoor air sensor.
Note
: While using CH MODE= 5 (HEADER&ODA&STAT) the ODA shutdown temperature is ignored and does not
stop the boiler from running.
Note:
Reference table and graph in section 1.6.2.2 for example of ODA to Header Temp relationship.
Note: Placing boiler in CH mode 5 will show the header temperature (HDR Supply) on the display in the place of the
supply temperature on the third line of text on the boiler.
1.6.2.7 CH Mode 6 (Header & Outdoor)
Two sensors are required to sense header temperature and outdoor temperature. A list of accessory choices for
different applications is shown in section 1.0 on page 3.
Description
This mode is a combination of CH Mode 2 (Outdoor Control) and CH Mode 4 (Header & Stat). The temperature is
maintained at the location of the header sensor and the setpoint is based on the ODA reset schedule that is
determined from an outdoor air sensor and the night setback feature. The closure of TB1/LV terminals 1 and 2 will
reduce the CH setpoint by the value of the night setback setting.
Note:
In this mode the boiler will always run to setpoint, as there is no enabling needed using this CH mode.
Note:
Reference table and graph in section 1.6.2.2 for example of ODA to Header Temp relationship.
Example
: Using the values, CH SP=180° F and Night Setback=10° F, when TB1/LV terminals 1 and 2 are open the
CH setpoint will be 180° F. When TB1/LV terminals 1 and 2 are closed the CH setpoint will be 170° F (180° F -10° F).
NOTE:
The boiler is enabled when the temperature of the outdoor sensor drops below the ODA
SHUTDOWN temperature which can be changed within the CH settings.
NOTE:
The TB1/LV terminals 1 and 2 (enable/disable) operate the switching on/off of the night setback
function. The night setback setpoint is set within CH settings.
NOTE:
The boiler is enabled by the TB1/LV terminals 1 and 2 (enable/disable) becoming closed or
shorted.
This circuit is energized internally.
DO NOT APPLY EXTERNAL POWER TO THESE
TERMINALS.
