Smith Cast Iron Boilers GT Series SENTRY 2100T CONTROLLER, 2100T Display Screen, Sentry Display

Page 26	GT INSTALLATION AND OPERATION INSTRUCTIONS
SENTRY 2100T CONTROLLER		Figure 37 - 2100T Display Screen

CAUTION: The T4.0 controller can only be used on the GT-400 and the T2.0 on the GT-150 & 200. Misapplication of the controller will result in improper boiler operation.

The Sentry 2100T controller is the central controller for the GT boiler. The Sentry handles all of the combustion logic, along with the energy management functions. The Sentry 2100T operates in two different modes, Conventional or Reset, see Figures 35 & 36.The mode is automatically determined by the presence of the outdoor sensor. When the Sentry 2100T detects the presence of the outdoor sensor the controller will operate in the Reset Mode. If the outdoor sensor is not installed, the controller will operate in the Conventional Mode.

NOTE: If the outdoor sensor is connected after the boiler has been started power to the boiler must be shut off and then turned back on.

Boiler Modulation

The GT boiler employs a pneumatic modulation system. This modulation system increases or decreases the speed of the blower to meet the heating demand. The gas valve pressure regulator senses the air pressure and adjusts the gas fl ow to ensure correct combustion. The term “Set Point” is used to indicate the desired temperature that the GT will maintain by increasing or decreasing the input.

Indirect Water Heaters

The Sentry 2100 comes with an input and output for

a120-volt indirect pump. When the A and C terminals are closed, dry contact, the boiler will go immediately to indirect domestic mode, whereby the indirect pump is activated, and the boiler will modulate to the LO setpoint.

Sentry Display

The Sentry 2100T contains four green lights that illuminate to indicate the boilers state of operation, Figure 37.

Figure 35 - Conventional Mode Operation Chart

Burner/Bruleur - Indicates that the ignition system is activated.

Circ. - Indicates that the heating pump is energized.

Circ. Aux.- Indicates a call for DHW, and Indirect pump or 3-way valve is activated.

Thermostat Demand - Indicates that terminals T-C are closed, iniating a call for heat.

The LED screen will display one of four values. A light will illuminate above the function to indicate what information is being displayed.

Water Temp - Indicates that the display is showing the boiler water temperature.

Air - if the air sensor is used. When illuminated, indicates that the display is showing outdoor air temperature.

Gas Input Value - Indicates the current input level. Figure 38 must be used to determine the actual input. GT-150 use 46 to 240, GT-200 use 40 to 240 and GT-400 use 35 to 195.

DHW Temp. - indicates that there is a call for domestic hot water.

	T-C & A-C Open	T-C Closed & A-C open	T-C Closed & A-C Closed	T-C Open & A-C Closed
Condition	Standby	Heating Only	Domestic Only	Domestic Only
Set Point	—	HI	L0	L0
Burner On	—	HI - DIF	LO-10	LO-10
Burner Off	—	HI + 10	200°F	200°F
Heat Circ.	Off	On	Off	Off
Aux. Circ.	Off	Off	On	On

Figure 36 - Reset Mode Operation Chart

	T-C & A-C Open	T-C Closed & A-C open	T-C Closed & A-C Closed	T-C Open & A-C Closed
Condition	Standby	Heating Only	Domestic Only	Domestic Only
Set Point	—	HI Calc.	L0	L0
Burner On	—	HI Calc - DIF	LO-10	LO-10
Burner Off	—	HI Calc + 10	200°F	200°F
Heat Circ. (C1)	Off	On	Off	Off
Aux. Circ. (Ap)	Off	Off	On	On