Grain Systems PNEG-1711 - Manual (Page 15)

PNEG - 1711
Page 15 of 22 06/30/2009
Digital Thermostat Owner’s Manual
3.3 Operating Modes
3.3.1 Hi / Lo Operation (Plenum Temperature Control)
There are three states the burner can assume when Hi / Lo operation is selected: High, Low, and Off.
Anytime the sensor temperature is below the temperature setpoint minus the differential, the controller will engage the
“High” state. Once the sensor temperature rises above the setpoint plus the temperature differential, the Thermostat
will enter “Low” mode and will remain in this state until one of two things happen:
1. The sensor temperature falls below the setpoint minus the temperature differential. At which point the
controller returns to “High” mode. This should be normal operation.
2.
The sensor temperature rises above the temperature setpoint plus the temperature differential plus the hi-
limit differential. If this occurs the controller will switch the “Off” position until the sensor temperature drops
below the temperature setpoint minus the temperature differential.
The relay position in each state is depicted below.
Table 2 - Hi / Lo Controller States
Controller State Relay 1 Relay 2
High Closed (0 Ω) Closed (0 Ω)
Low Closed (0 Ω) Open (∞ Ω)
Off Open (∞ Ω) Open (∞ Ω)
The default screen displays current state of controller, current sensor temperature, and current setpoint.
Figure 5 - Default Hi / Lo Screen
3.3.2 On / Off Operation (Plenum Temperature Control)
There are two states the controller can assume using On / Off operation: On and Off.
Anytime the sensor temperature is below the setpoint minus the temperature differential, the Thermostat will be in the
“On” state. If the sensor temperature rises above the setpoint plus the differential, the Thermostat will be in the “Off”
state.
The relay position in each state is depicted below.