FCU brands that still ship three-speed coils often need more panel relays than the wall glass can host alone. A fan coil thermostat with Modbus relay extender for 3-speed fan pairs Alledio's 230 VAC OEM thermostat with a DIN-rail Modbus relay extender - so the brand face stays in the room and extra switching lives in the panel.
OEMModbusRelay ExtenderFCU3-Speed230 VAC
This post is the extra-relays install path after the Modbus-relay and 230 VAC thermostat briefs. It is not a Room Controller I/O matrix post. The wall SKU is the Alledio OEM Thermostat; the extender is Alledio MR5 (ALL-MR5) on RS-485 - confirm loads and modes on the product datasheet.
Who this is for
Read this if you are an FCU, AHU, or DX OEM product manager, or a BMS device maker, evaluating a white-label wall thermostat plus panel relay expansion - not an installer webshop brick.
Installers and SIs buy through your channel. Alledio sells OEM-only. Typical applications on the thermostat page are fan coils, air handlers, DX, and other local HVAC that need relay outputs.
Do not confuse this with the low-voltage Room Unit or the I/O-heavy Room Controller. Those SKUs answer different RFQs. Here the glass is the thermostat; the extender is the power stage when you need more contacts than the wall unit already carries.
Bring controls engineering and industrial design into one RFQ. One owner signs the Modbus map. One owner signs the logo and UI. That keeps NRE on brand surfaces instead of a second electronics spin.
Fan coil thermostat with Modbus relay extender for 3-speed fan — when OEMs need it
Three-speed AC fans still dominate many European FCU lines. Speed 1 / 2 / 3 / Auto / off are contact closures. Heat and cool are contact closures. The published thermostat already includes fan-speed and heat/cool relays on 230 VAC.
OEMs still ask for a Modbus relay extender when they need synchronized multi-coil switching, auxiliary heaters, lighting, or shading from the same room glass - or when they want the power stage in the panel while the brand UI stays flush on the wall. The public MR5 page positions that DIN-rail module for FCU fan and valve switching, standalone relays, and curtain/shading modes.
Write the RFQ so the wall thermostat and the extender share one RS-485 plan. Baud, parity, slave IDs, and failsafe behaviour belong in the same pack as artwork. Do not paste an EC or 0-10 V fan path into this brief unless you quoted a different model.
Thermostat stack: glass, 230 VAC relays, Modbus
Start from the live OEM Modbus relay thermostat facts, then add the extender only where the panel needs more contacts. Power on the thermostat page is 230 VAC.
Mechanics you can defend today: 98 x 98 x 14 mm, 150 g, IP20, ABS plus scratch-resistant glass, flush EU box O 60 mm. Display is 3.5-inch LCD at 480 x 320 with capacitive touch and auto brightness. Standard sensors are digital temperature and humidity; VOC, CO2, and external NTC are optional.
Modbus RTU on RS-485 is the supervisory copper pair. Wi-Fi 2.4 GHz STA is listed for connected SKUs; MQTT is named for cloud or proprietary web services. That radio does not replace the copper pair to the extender.
Four thermostat models add optional AO/DO combinations on top of power, Modbus, and fan-speed relays. Those analogue and digital options are models. They are not a licence to write EC fan control or a Room Controller I/O matrix into this article.
MR5 (ALL-MR5): DIN-rail relays for 3-speed FCU
Alledio publishes the MR5 (ALL-MR5) as a compact DIN-rail 5-channel Modbus relay extender. Public facts from andivi.com: 230 V AC supply, five relays, up to 5 A per contact with 5 A total through the shared common, RS-485 Modbus, IP30, ~81 x 44 x 34 mm, ~100 g, CE / RoHS / WEEE, designed in Slovenia / EU.
Three application modes are listed: Fan Coil (3-speed AC fan with interlocking plus heating/cooling ON/OFF valves), Standalone Relay (five freely usable relays), and Curtain/Shading (up to two drives with open/close interlocking). Addressing and factory reset use the on-device button and LED - confirm the exact procedure on the datasheet.
An MR3 3-channel variant is also listed on the same page. Leave register maps, baud defaults beyond the datasheet, and catalogue KNX / BTL claims off the RFQ until confirmed. If a load profile is unclear, confirm with the datasheet before you freeze the RFQ.
Public language also notes that one thermostat can manage multiple fan coils when appropriate relay modules distribute load - still subject to combined electrical capacity and control logic. That is an integration conversation, not a webshop SKU.
White-label surfaces and RFQ discipline
OEM customisation covers exterior logo, UI colours, widgets, housing colourways, optional VOC/CO2, packing and docs. You pay for the delta. A hotel pack and an office pack can share one electronics revision.
The same brand discipline as the live white label FCU thermostat post applies: white label is not a sticker on a catalogue brick. List each surface, who owns artwork, and whether the change is NRE. Keep this article on the thermostat + extender stack - Room Controller 0-10 V matrices belong on a different RFQ, even when the title template uses that suffix.
Not a catalogue SKU here:KNX. BACnet is not in standard thermostat firmware; custom BACnet can be discussed on request for specific datapoints - roadmap / on-request language only, per the product FAQ. Bluetooth 5 LE is ready; the GATT map is a client specification.
Commissioning stays honest when the RFQ names cable class for RS-485, the slave-ID plan for the glass and for each extender, and what the relays do on bus loss. Field teams should not create a site dialect for failsafe or anti-freeze.
If the project also needs separate IAQ sensing, keep that on the Multi-Sensor brief rather than stuffing unquoted sensors into the thermostat RFQ. The thermostat already monitors temperature and humidity; optional VOC and CO2 stay options, not silent defaults.
How the room feels still matters - the same thread as Beyond design: it's how it feels. Brightness, night schedule, and absence behaviour are firmware requirements. Write them beside the extender contact schedule so NRE does not split into two silent projects.
Product proof
| Topic | Published spec |
|---|---|
| Wall product | Alledio OEM Thermostat (Modbus / relay) |
| Thermostat power | 230 VAC |
| On-board fan relays | Speed 1 / 2 / 3 / Auto / off |
| On-board H/C relays | Heating / cooling |
| Extender | Alledio MR5 (ALL-MR5), 5x relays, DIN rail |
| Extender power | 230 V AC; ~3.5 VA |
| Extender ratings | Max 5 A per contact; max 5 A through shared common |
| Bus | RS-485 Modbus RTU (thermostat + extender) |
| Display | 3.5-inch LCD, 480 x 320, capacitive, auto brightness |
| Origin | Designed Slovenia, manufactured EU |
Use this table in the brand pack, then attach logo, UI screens, and the MR5 datasheet separately. Leave unpublished current cells empty until the datasheet is current.
FAQ
Is this the same as specifying a Room Controller?
No. The title template may say 'OEM Room Controller,' but this RFQ is the thermostat + Modbus relay extender path. Room Controller I/O is a different SKU.
Does the wall thermostat already have 3-speed relays?
Yes. Published fan path is on-board relays for speed 1 / 2 / 3 / Auto / off plus heat/cool. The extender adds panel-level contacts when you need more switching.
Can we assume EC or 0-10 V fan control?
No. Keep EC out of this stack. Ask analogue fan as a separate model question.
Can we get samples?
Yes. Samples are available with demo firmware or test firmware, under NDA. This is not a free webshop sample. Start on /oem.
What is the MOQ for the thermostat?
The usual thermostat MOQ is 1,000 pcs, and it is negotiable. If several different thermostat versions are combined and the total exceeds 1,000 pcs, 500 on a version can be possible. Do not assume Room Unit or Room Controller family bundling in this RFQ.
Is BACnet or KNX a catalogue SKU here?
KNX is not a catalogue SKU. BACnet is not in standard thermostat firmware; custom BACnet is on request for named datapoints - confirm on the product page.
What to do next
Open the Alledio OEM Thermostat page, review the MR5 facts on the public Modbus relay extender page, then start an OEM conversation for logo, UI, firmware, samples, and extender quantities. Bring fan type (three-speed relays), 230 VAC, Modbus map, MOQ, and artwork. Link About and Contact when you are ready for the RFQ. Pair Multi-Sensor only if the project needs separate IAQ sensing - see the Multi-Sensor page. That is how a fan coil thermostat with Modbus relay extender for 3-speed fan becomes a branded OEM line instead of a sticker.
