Salus RT520 Thermostat Wiring Diagram
Wiring Configurations
The Salus RT520 thermostat supports two primary wiring configurations for boiler control:
Configuration 1: Boiler Connection (ON/OFF Thermostat)
This setup configures the RT520 as a simple ON/OFF switch for the boiler. The thermostat is powered by batteries (3V, 2 x AA). It connects to the boiler's control circuit via its COM, NO (Normally Open), and NC (Normally Closed) terminals. This connection is used for basic ON/OFF thermostat functionality, as indicated by the "Boiler Connection*" label pointing to the boiler's contacts.
Diagram Description: A representation of the RT520 unit, showing a battery symbol (3V, 2 x AA) and a switch with three terminals labeled NC, COM, and NO. These terminals are connected by lines to a separate unit labeled "BOILER CONNECTION*", which features a flame symbol (?) indicating the boiler's heating function.
Configuration 2: Boiler Connection (OpenTherm)
This configuration enables advanced communication between the RT520 and compatible boilers using the OpenTherm protocol. The thermostat is battery-powered (3V, 2 x AA). It connects to the boiler via terminals A and B, designated as "BOILER CONNECTION*" for OpenTherm communication.
Diagram Description: A representation of the RT520 unit, showing a battery symbol (3V, 2 x AA) and two terminals labeled A and B. These terminals are connected by lines to a separate unit labeled "BOILER CONNECTION*" and "OPENTHERM", which features a flame symbol (?).
Legend
| Symbol | Description |
|---|---|
| ? | Battery powered |
| [AC Power] | 230V AC power supply |
| [fuse] | Fuse |
| [Voltage-Free Output] | Voltage free output |
| [Input Terminals] | Input terminals |
| [AC Voltage Output] | 230V AC voltage output |
| [NO Contact] | Contact normally open |
| [NC Contact] | Contact normally closed |
| ?️ | NC/COM/NO switch |
| ? | Boiler - Boiler connection * - Boiler's contacts for ON/OFF thermostat (according to the boiler's instructions) |
| ? | Wireless communication |
| ? | Pump |
| ⚙️ | Valve actuator |
| ?️ | Temperature sensor |
| ? | 3-speed 230V AC fan |
| ? | Light bulb or other load |
| [Thermoelectric Actuator] | Thermoelectric actuator (T30NC) |
| ⏰ | Time programmer |
| [External NO Contact] | External normally open contact |
| [Voltage Converter] | Voltage converter |
