FC Room Thermostat
The Legom FC1D Intelligent Thermostat is a room thermostat for domestic water-based underfloor heating and cooling systems, supporting both heating and cooling mode in a single device. Unlike heating-only thermostats, the FC1D features a dedicated CO (changeover) terminal that automatically switches the thermostat between heating and cooling mode when a 230V signal is applied — enabling seamless integration with central heating/cooling changeover systems without manual mode selection by the user.
Compatible with 100–240VAC at 50/60Hz, NTC internal and external sensor configurations, and both standalone and base station installations, the FC1D adds a child lock function and a WiFi working indicator to the standard Legom thermostat feature set. Six configurable advanced parameters (H1–H4, L1, L2) provide comprehensive control over temperature compensation, protection thresholds, screen display time, and power-on behavior. Available in Black and White in an 86 × 86 × 13mm panel.
Key Benefits
- Heating and cooling dual mode – Controls both underfloor heating and radiant cooling systems from a single thermostat, making it suitable for heat pump installations and four-pipe fan coil systems where the same terminal serves both functions seasonally
- Automatic CO changeover – The CO terminal automatically switches the thermostat to cooling mode when a 230V signal is present, and returns to heating mode when the signal is absent — no manual mode switching by the occupant required
- Child lock function – Long press Up and Down simultaneously for 5 seconds to activate or deactivate the keypad lock, preventing unauthorized temperature changes
- WiFi working indicator – Dedicated WiFi status indicator on the display confirms wireless connectivity status at a glance
- Six advanced parameters – H1 (temperature compensation), H2 (start-up differential), H3 (high temp protection), H4 (low temp protection), L1 (screen display time), and L2 (power-on mode) provide comprehensive configuration for different installation requirements
- Valve protection function – If the thermostat has not operated for 15 days, it automatically opens the valve for 15 minutes to prevent thermal actuator valves from seizing due to prolonged inactivity
- Internal and external sensor modes – Supports internal sensor only, external probe only, or combined ALL mode (internal controls setpoint, external limits floor temperature)
- Wide voltage compatibility – Operates on 100–240VAC at 50/60Hz for both European and international installations
- Base station compatible – Can be wired directly to thermal actuators or integrated with the Legom BS-Y6 or TCC base station for centralized multi-room control
Technical Specifications
| Parameter | Specification |
|---|---|
| Model | FC1D |
| Operating Voltage | 100–240VAC ~ 50/60Hz |
| Temperature Control Range | Internal: 5°C ~ 35°C / External: 5°C ~ 60°C |
| Temperature Control Accuracy | ± 1°C |
| Temperature Sensor | NTC |
| Load Current | 3A (MAX) |
| Housing Material | PC flame retardant |
| Dimensions | 86 × 86 × 13mm |
| Color Options | Black / White |
Terminal Functions
| Terminal | Function |
|---|---|
| 1 | N line |
| 2 | L line |
| 3 | Normally closed valve |
| 4 | CO changeover (230V input triggers cooling mode) |
| 5/6 | NTC external temperature sensor |
Advanced Settings Parameters
| Code | Function | Default | Adjustable Range |
|---|---|---|---|
| H1 | Temperature compensation | 0°C | -9°C ~ +9°C |
| H2 | Start-up temperature difference | 2°C | 1°C ~ 5°C |
| H3 | High temperature protection | 45°C | 35°C ~ 60°C |
| H4 | Low temperature protection | 5°C | 5°C ~ 9°C |
| L1 | Screen display time | 60s | 10s ~ 60s or L (always on) |
| L2 | Power-on mode | 0 (Automatic) | 0: Automatic / 1: Manual |
Error Codes
| Code | Meaning |
|---|---|
| E1 | Internal sensor short circuit |
| E2 | Internal sensor open circuit |
| E3 | External sensor short circuit or not connected |
| E4 | External sensor open circuit or not connected |
Application & Use Cases
- Underfloor heating and cooling systems – The primary application. The FC1D controls both heating in winter and radiant cooling in summer from the same thermostat, eliminating the need to replace or rewire the thermostat when switching between seasons
- Heat pump installations with seasonal changeover – The CO terminal allows a central heat pump controller to automatically switch all FC1D thermostats in the building from heating to cooling mode when the system changes season, without occupant involvement
- Fan coil unit systems with heating and cooling – Applied in four-pipe fan coil installations where the same room thermostat manages both heating and cooling valve commands depending on seasonal mode
- Centralized multi-room heating/cooling systems – Can be connected to the Legom BS-Y6 or TCC base station for centralized zone management across multiple rooms in a building served by a combined heating and cooling system
- Installations requiring child-proof controls – The child lock function makes the FC1D appropriate for nurseries, classrooms, hotel rooms, and other environments where unauthorized temperature adjustments must be prevented
Installation Notes
- Install at 1.4 metres above floor level, away from direct sunlight, drafts, and heat sources
- Installation must be carried out by qualified electrical personnel with an independent isolation switch fitted at the front-end power supply
- To disassemble: insert a 3.5mm flat screwdriver along the panel seam and gently lever to open. Move the panel up and down to separate from the bottom shell
- Wire according to the terminal diagram on the bottom shell: Terminal 1 (N), 2 (L), 3 (NC valve), 4 (CO changeover input), 5/6 (NTC external sensor)
- CO terminal wiring: Connect the seasonal changeover signal from the heat pump or central controller to terminal 4. When 230V is present at terminal 4, the thermostat switches to cooling mode automatically. When 230V is absent, the thermostat defaults to heating mode
- Fasten the bottom shell to the wall concealed box, connect the display board to the power board via cable socket, fit the panel, and adjust the gap
- Do not exceed the 3A maximum load current
- Child lock: Long press Up and Down simultaneously for 5 seconds to activate or deactivate
- Factory reset: Within 20 seconds of powering off, press Up and Down simultaneously for 5 seconds to restore factory defaults
Frequently Asked Questions
What is the difference between the FC1D and the Volcano RB-2305HT thermostat?
Both thermostats share the same core specifications — 100–240VAC, NTC sensor, 3A load, 86mm panel, ±1°C accuracy, and base station compatibility. The key differences are: the FC1D supports both heating and cooling modes with automatic CO changeover, while the RB-2305HT is a heating-only thermostat. The FC1D also adds a child lock function, a WiFi status indicator, and two additional advanced parameters (L1 screen display time and L2 power-on mode) not present in the RB-2305HT. Choose the FC1D for systems that switch between heating and cooling seasonally, or where child lock is a requirement.
How does the CO changeover function work?
Terminal 4 on the FC1D accepts a 230V signal from a central heat pump controller or seasonal changeover device. When this 230V signal is present, the thermostat automatically switches to cooling mode — the display shows the cooling indicator and the thermostat commands cooling rather than heating. When the 230V signal is absent, the thermostat defaults to heating mode. This allows a building-wide seasonal switch from heating to cooling to be made at the central controller level without requiring manual mode changes at each individual room thermostat.
What does the L2 power-on mode parameter do?
L2 determines the thermostat’s behavior when power is first applied or restored after a power interruption. In Automatic mode (L2 = 0, default), the thermostat resumes its previous operating state — if it was on before the power interruption, it turns on again automatically. In Manual mode (L2 = 1), the thermostat always starts in the off state after power is applied and requires manual activation. Manual mode is preferred in commercial or rental installations where the thermostat should not activate automatically after a power failure.
What does the valve protection function do and when does it activate?
If the FC1D thermostat has not commanded the valve to open for 15 consecutive days — for example, during a seasonal shutdown or extended absence — it automatically forces the thermal actuator valve open for 15 minutes. This prevents the valve from seizing in the closed position due to prolonged inactivity, which is a common cause of valve failure in systems that are shut down for extended periods.
How do I activate the child lock?
In the powered-on state, press and hold the Up and Down buttons simultaneously for 5 seconds. The child lock icon will appear on the display confirming the keypad is locked. Repeat the same action to unlock. When the child lock is active, the temperature setpoint and all button functions are disabled.
Is the FC1D compatible with the Legom base station?
Yes. The FC1D is compatible with the Legom BS-Y6 6-zone and TCC 8-zone base stations for centralized multi-room temperature control with shared pump and boiler management. When connected to a base station, the FC1D’s switching commands are forwarded to the base station, which manages the pump and boiler or chiller circuit centrally.
OEM & ODM Customization
Legom supports OEM and ODM services for the FC1D Thermostat series. Housing color, branding, and configuration parameters can be customized for distributor and system integrator requirements. All customization projects are handled with strict confidentiality. Contact us via WhatsApp or info@legomsmart.com.
User Manual
Product information last reviewed by the Legom Technical Team. For the most current specifications, refer to the official datasheet or contact our sales team.
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Legom is a direct manufacturer offering end-to-end OEM and ODM services. With our in-house engineering and production capabilities, we work closely with distributors and system integrators to deliver fully customized solutions under strict NDA.
