Apus Room Thermostat
The Legom Apus Room Thermostat RT-A1 is a premium heating and cooling thermostat featuring an intuitive rotary-push knob interface for temperature setting and menu navigation, paired with a large backlit LCD display that shows all settings and status icons simultaneously. Designed for domestic water-based underfloor heating and radiant cooling systems, the Apus operates at 230VAC and can control up to 5 thermal actuators simultaneously — making it suitable for larger zones requiring multiple manifold loop control from a single thermostat.
Available in White and Black, the Apus combines a language-neutral symbol display, Home and Away operating modes, programmable comfort temperatures, and four advanced parameters (H1–H4) in an 86 × 86 × 31mm surface-mount housing. Both NC and NO actuator configurations are supported, and the thermostat can be connected directly to actuators or integrated with a Legom base station for centralized multi-zone control.
Key Benefits
- Rotary-push knob with fine ratchet – Temperature adjustment and menu navigation by rotating the knob and pressing to confirm — a more tactile and precise interaction than button-only thermostats, with vertical ridges on the knob surface for grip even with wet hands
- Controls up to 5 actuators simultaneously – The highest actuator capacity among Legom room thermostats, making the Apus suited for larger rooms or open-plan spaces served by multiple manifold loops from a single thermostat
- Heating and cooling dual mode – Supports both underfloor heating and radiant cooling operation with separate configurable temperatures for heating and cooling modes in both Home and Away presets
- NC and NO actuator compatibility – Works with both Normally Closed and Normally Open thermal actuators, providing compatibility flexibility for different system designs
- Home and Away operating modes – Separate temperature presets for occupied (Home) and unoccupied (Away) states, with independent heating and cooling setpoints configurable for each mode
- Language-neutral symbol display – All icons and indicators are symbol-based rather than text-based, making the display universally readable regardless of the user’s language
- High output of 230VAC 5A – Higher output rating than the Volcano and FC1D thermostats (both 3A), supporting the larger combined load of up to 5 actuators
- On-surface wall installation – Mounts directly onto the wall surface or an embedded box without requiring a concealed back box, offering greater installation flexibility
- Photoelectric thyristor / solid state relay switching element – No mechanical relay contacts, resulting in silent switching, longer service life, and reduced wear
- Screen auto-off after 8 seconds – Display backlight turns off automatically after 8 seconds of inactivity to save energy and reduce glare in sleeping areas
Technical Specifications
| Parameter | Specification |
|---|---|
| Model | RT-A1 / RT-A2 |
| Operating Voltage | 230VAC ± 10%, 50/60Hz |
| Output | 230VAC, 5A |
| Power Consumption | < 1W |
| Fuse | Slow break 1A / 250V |
| Max. Connectible Actuators | 5 |
| Actuator Control Direction | NC / NO |
| Target Temperature Setting Range | 5°C to 35°C |
| Target Temperature Resolution | 1°C |
| Actual Temperature Measuring Range | 0°C to 90°C |
| Temperature Correction Range | -9°C to +9°C |
| Measuring Accuracy | 0.1°C |
| Control Accuracy | ± 1°C |
| Antifreeze Temperature | 5°C |
| Admissible Ambient Temperature | 0°C to 50°C |
| Storage Temperature | -20°C to +70°C |
| Admissible Humidity | 80%, non-condensing |
| Sensor | NTC100K 1% |
| Switching Element | Photoelectric thyristor, solid state relay |
| Screen | LCD with LED backlight |
| Background Illumination | Auto-off after 8 seconds of inactivity |
| Color | White / Black |
| Dimensions | 86 × 86 × 31mm |
| Installation Type | On-surface or embedded box wall installation |
Terminal Functions
| Terminal | Function |
|---|---|
| 1 | L line |
| 2 | N line |
| 3 | Normally closed valve (NC) |
| 4 | Normally open valve (NO) |
| 5/6 | Dry contact connection |
Advanced Settings Parameters
| Code | Function | Default | Adjustable Range |
|---|---|---|---|
| H1 | Temperature compensation | 0°C | -9°C ~ +9°C |
| H2 | Start-up temperature difference | 2°C | 0°C ~ 9°C |
| H3 | High temperature protection | 45°C | 30°C ~ 60°C |
| H4 | Low temperature protection | 5°C | 5°C ~ 10°C |
Application & Use Cases
- Large-zone underfloor heating systems – With support for up to 5 actuators per thermostat, the Apus is suited for large open-plan living areas, master bedrooms, or commercial spaces where multiple manifold loops serve a single temperature zone
- Underfloor heating and radiant cooling systems – The dual heating/cooling mode with separate Home and Away temperature presets makes the Apus appropriate for year-round four-pipe or heat pump systems that switch seasonally
- Hospitality and premium residential installations – The rotary knob interface, language-neutral display, and clean aesthetic make the Apus suitable for hotel rooms, serviced apartments, and premium residential projects where user experience and visual design are selection criteria
- Retrofit installations without concealed back boxes – The on-surface installation option allows the Apus to be mounted directly on finished walls without drilling for a back box, reducing installation disruption in renovation projects
- Multi-zone systems with base station integration – Compatible with the Legom BS-Y6 and TCC base stations for centralized multi-room heating and cooling control with shared pump and boiler management
Installation Notes
- Install at approximately 150cm above floor level, at least 30cm from corners and doors, away from heat sources, direct sunlight, radiators, drafts, and areas with excessive moisture
- The Apus can be installed on a surface directly on the wall or in a standard embedded back box — choose the method that best suits the installation environment
- Wire using a multi-core connection cable according to the terminal diagram: Terminal 1 (L), 2 (N), 3 (NC valve), 4 (NO valve), 5/6 (dry contact)
- Remove the rotary knob (pull outward), then loosen the four corner screws on the bottom plate to access the connection terminals
- Connect wiring per the wiring diagram printed on the device. Do not allow water, mud, or other contaminants into the thermostat during installation
- Installation must be carried out by qualified electrical personnel with an independent isolation switch at the front-end power supply
- The thermostat housing depth is 31mm — verify adequate wall depth or surface clearance before selecting the installation method
- Factory reset: In the function menu, long press the On/Off button for 5 seconds to restore factory defaults
- Screen lock: Activate from the function menu. Long press for 5 seconds to unlock
Frequently Asked Questions
How does the Apus thermostat differ from the Volcano RB-2305HT and FC1D?
All three are Legom room thermostats for water-based underfloor heating systems. The key differences are in interface, output capacity, and installation type. The Apus uses a rotary-push knob for navigation rather than discrete buttons, supports up to 5 actuators versus 1 for the Volcano and FC1D, has a higher output of 5A versus 3A, uses a solid state relay rather than a mechanical relay for silent switching, and supports on-surface wall installation in addition to concealed box mounting. The Apus also supports both NC and NO actuators directly, while the Volcano and FC1D focus on NC configurations. Choose the Apus for premium installations, larger zones, or where the rotary interface is preferred.
What is the difference between Home mode and Away mode?
Home mode is the standard occupied temperature setpoint — the temperature the thermostat maintains when the room is in regular use. Away mode is a reduced setpoint used when the room is unoccupied or when the occupant is absent, saving energy by maintaining a lower heating temperature or a higher cooling temperature. Both modes have separate configurable setpoints for heating and cooling, and the default Away temperature is 16°C for heating and 22°C for cooling. The user switches between modes via the function menu.
Why does the Apus use a solid state relay instead of a mechanical relay?
A solid state relay (photoelectric thyristor) switches electrically rather than mechanically. This means no audible click when switching, no mechanical wear from repeated actuation over the thermostat’s service life, and faster response time. In underfloor heating applications where the thermostat may switch on and off hundreds of times per day over many years, the absence of mechanical contact wear is a meaningful durability advantage.
Can the Apus control both NC and NO actuators at the same time?
The Apus has separate terminals for NC (terminal 3) and NO (terminal 4) connections, plus a dry contact output (terminals 5/6). This means it can simultaneously control actuators of different types connected to the appropriate terminals, providing flexibility for mixed systems or installations where the actuator type cannot be changed.
What error codes does the Apus display?
E1 indicates a sensor short circuit fault and E2 indicates a sensor open circuit fault. When either error code appears, the thermostat stops operating until the fault is resolved. Check the NTC sensor connections for short circuits (E1) or disconnected/broken wires (E2) and repair or replace the sensor as needed.
Is the Apus compatible with the Legom base station?
Yes. The Apus RT-A1 can be integrated with the Legom BS-Y6 6-zone or TCC 8-zone base station for centralized multi-room heating and cooling control with shared pump and boiler management across the building.
OEM & ODM Customization
Legom supports OEM and ODM services for the Apus 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.
