Wired switching centre Termojet (8 zones, 19 actuators) TJ03CWRD

Termojet TJ-03-C — a wired 8-zone switching centre for hydronic underfloor heating and combined heating systems. It is the "brain" of the zone system: it receives heat demand signals from up to 8 room thermostats, opens the corresponding thermal actuators on the manifold, starts the circulation pump and the boiler via a dry contact — all automatically, without human intervention.

Technical Specifications

How It Works

The operating principle is two-position zone control. A room thermostat (e.g. HT-120) detects that the room temperature is below the setpoint and sends a demand signal to the TJ-03-C via the wired channel. The switching centre:

1. Applies 230 V to the corresponding output — the thermal actuator 920018TJ opens and unblocks the floor loop.
2. Switches on the circulation pump (230 V output) to circulate the heat carrier through the open circuit.
3. Closes the boiler dry contact — the boiler receives the command to supply heat.

When the thermostat detects that the setpoint has been reached, the signal is removed, the actuator closes, and if no other zone demands heat, the boiler and pump are switched off. The pump and boiler switch-off delay times are adjustable via jumper switches on the board.

Application Scenarios

• New building with underfloor heating. The TJ-03-C is mounted in a distribution board or on the wall of the plant room — the best solution for systems where thermostat cables are laid during construction.
• Building with multiple circuits. Up to 19 actuators across 8 zones cover large properties: kitchen, living room, 4 bedrooms, bathroom, hallway, and entrance area — all independently controlled.
• Combined system. Underfloor heating + radiators in the same building: each zone has its own thermostat and actuator, with the boiler controlled by a single TJ-03-C.
• Retrofit of an existing system. If thermostat wiring is already in place, the TJ-03-C replaces the old controller without re-routing any cables.

Advantages of the TJ-03-C

• Up to 19 thermal actuators — maximum coverage for large buildings with multiple loops per zone.
• Boiler dry contact — compatible with gas, electric, and solid-fuel boilers from any manufacturer.
• 230 V pump output — centralised circulation control without a separate relay.
• DIN rail mounting — easy integration into an existing electrical distribution board.
• LED zone indication — the status of each zone is visible at a glance, without an app or smartphone.
• Wireless alternative available: TJ-03-RF centre (8 zones, up to 16 actuators) for systems without thermostat cables.

TJ-03-C and Heat Pump

Zone control of underfloor heating via the TJ-03-C is the optimal solution for a heat pump. Low-temperature underfloor heating with per-room zoning allows the heat pump to maintain the minimum heat carrier temperature, which directly increases COP and reduces electricity costs. The boiler activates only when there is an actual demand from at least one zone — no idle cycles. For more information about Termojet heat pumps, visit tjheatpump.com.ua.

Frequently Asked Questions

How many thermal actuators can be connected to the TJ-03-C?
Up to 19 actuators distributed across 8 zones: zone 1 — maximum 4 actuators, zone 2 — maximum 3, zones 3–8 — 2 actuators each. Use Termojet thermal actuators 920018TJ with M30×1.5 thread for connection.

Is the TJ-03-C compatible with Wi-Fi thermostats HT-120 and HT-130?
Yes, it is compatible. The HT-120 and HT-130 connect via wire to the thermostat inputs HZ1–HZ8. The Wi-Fi function of these thermostats operates independently — the thermostat can be controlled both from a phone and through the TJ-03-C. The full zone control catalogue is available in the Termojet section.