TQR Heater Wiring Diagrams

Overview

This article provides guidance on interpreting and applying wiring diagrams across the Braemar TQR ducted gas heater range, grouped by efficiency (star rating) and control strategy.

The TQR series replaces older TQ / TQM / TQS heaters depending on efficiency level (single-stage, two-stage, or modulating condensing of non-condensing systems).

Wiring Diagrams

Diagram

Models


644110

TQR3, TQRD3

Single stage gas valve (ON/OFF only). No staging or modulation. Basic relay control.

644301

TQR4

Two-stage gas valve (LOW + HIGH). Extra wiring for second coil and stage control output.

644141

TQR5, TQRD5

Modulating gas valve. No stages – PCB sends variable signal to control output. Uses sensors and comms.

644141

TQR6

Same as 5★ PLUS condensate and additional safety wiring (drain, sensors, flue fan where fitted).

Key Differences 

1. Gas Valve Control

  • 3★ (644110) → 1 output (ON/OFF)
  • 4★ (644301) → 2 outputs (LOW + HIGH)
  • 5★ / 6★ (644141) → Modulating signal (no stages)

2. PCB Type

  • 3★ / 4★ → Relay-based control
  • 5★ / 6★ → Modulating ICS control (communication + sensors)

3. Additional Circuits

  • 4★ → Extra wiring for stage 2
  • 5★ → Sensor and modulation control wiring
  • 6★ → Adds condensate / flue / extra safety circuits

Bottom Line

  • The wiring diagram changes based on how the gas valve is controlled (on/off → staged → modulating).
  • 6★ only differs from 5★ by added components, not core control logic.
  • TQR vs TQRD do not change wiring diagrams.

3★ Heaters – Single Stage (Diagram 644110)

4★ Heaters – Two Stage (Diagram 644301)

 5★ Heaters – Modulating (Non-Condensing) (Diagram 644141)


6★ Heaters – Modulating Condensing (Diagram 644141)


Wiring Identification Tips (Field Use)

Quick Identification Guide

  • Single gas valve coil → 3★ single stage
  • Two gas valve coils (Hi/Low) → 4★ two stages
  • Modulating gas valve plug → 5★ / 6★
  • Modulating gas valve with Condensate pressure switch and tubing → 6★ condensing