ENVI
®
Control
15
1.6.2.2 CH Mode 1 (ODA & Stat)
Outdoor Sensor required.
A list of accessory choices for different applications is shown in section 1.0 on
page 3.
Description
In this mode, upon enabling the boiler, setpoint is varied by the outdoor air temperature (ODA). The ENVI
®
control
fires and modulates the boiler to maintain outlet water temperature at the setpoint which is determined by the outdoor
air temperature and its settings. The upper (HYSTERESIS OFF) and lower (HYSTERESIS ON) temperature
differentials control the temperature at which the burner turns on or off.
(FACTORY SETTINGS SHOWN ABOVE)
The Outdoor air sensor reads outdoor air temperature and sends it back to the control. The setpoint is established
based on the outdoor air temperature. If the outdoor air temperature is below the (HIGH ODA TEMP), the boiler
control begins to maintain a setpoint set by the (MIN ODA SETP). As the outdoor air temperature drops, the setpoint
temperature increases until (LO ODA TEMP) is reached by the outdoor air temperature. When the outside air
temperature has dropped to meet the (LO ODA TEMP) setting, the setpoint of the boiler will be operating at (MAX
ODA SETP).
Example
: Using the values in the table shown below, the boiler setpoint is 80° F (MIN ODA SETPT) when the
outdoor air temperature is 70° F (HI ODA TEMP). As the outdoor air temperature drops, the boiler setpoint increases
until the outdoor air temperature is 20° F (LO ODA TEMP). When this occurs, the boiler reaches its maximum
setpoint of 180°F (MAX ODA SETPT). If the outdoor air temperature drops further, the boiler setpoint remains at 180°
F.
Within CH Settings
Hi ODA Temp (Outdoor TMax)
70
°F
Min ODA SetP (Setpoint TMin)
80
°F
Low ODA Temp (Outdoor TMin)
20
°F
Max ODA Setp (Setpoint TMax)
180
°F
ODA shutdown
68
°F
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.
NOTE:
while using CH MODE 1 (ODA&STAT) the ODA shutdown temperature is ignored and does not
stop the boiler from running.
