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OPERATING INSTRUCTIONS
V-10 TOUCH SCREEN BOILER CONTROLLER
2.1.1 Thermostat Connections
The controller is designed to be compatible with most common thermostats
including simple single contact (mercury switch) types as well as most power
stealing type thermostats.
The standard connection for common thermostats that provide a simple contact
closer for the boiler is shown in the Electrical Ladder Diagram on the previous
page.
The Therm. 24Vac (TB2 terminal 5) provides 24 volts AC to all thermostats (up
to four). This will connect to the “R” terminal on the thermostat. Each individual
thermostat’s “W” terminal connects separately to one of the controller input
terminals Therm. 1 (TB2-6), Therm. 2 (TB2-7), Therm. 3 (TB2-8) or Therm. 4
(TB2-9) depending on the load it is intended to control.
Power stealing thermostats take a small amount of current from the 24 VAC
to operate their internal electronics. To complete the 24 VAC circuit required
to operate power stealing thermostats the controller includes an internal 2740
ohm resistor from the thermostat input to ground. This internal resistor limits
the power available to the thermostat and for some models additional power
is required for proper operation. Thermostats that require this extra amount of
power (for example the Honeywell T8775) will have a resistor available from the
manufacturer capable of supplying the required power. The controller’s Therm
GND terminal (TB2-10) is provided to allow simple installation of the power
resistor. Connect the resistor from the thermostat’s input terminal to the Therm.
GND (TB2-10) terminal.
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