WITH3 RF Wireless Wall-Hung Boiler Thermostat

Overview

The SunAura WITH3 is a 433 MHz RF wireless thermostat built specifically for wall-hung gas boilers and wet central heating systems. A complete control set consists of two parts: a battery-powered room thermostat (the transmitter), which sits wherever you want to measure the living temperature, and a compact RF receiver that is wired directly to the boiler’s thermostat terminals. Because the link between the two is radio rather than copper cable, you can place the room unit in the hall, bedroom or living room — wherever the temperature reading actually matters — without chiselling walls or pulling wires under floors.

This no-wire retrofit design is the main reason installers choose the WITH3. On an existing wall-hung boiler installation, running a two-core cable from the boiler location to the room control point is often the most expensive and disruptive part of the job. The WITH3 removes that step: the receiver mounts next to or beside the boiler, pairs with the room thermostat at the push of a button, and the boiler then follows the temperature you set, exactly as it would with a conventional wired room thermostat. It supports a full 7-day heating programme (5+2, 6+1 or 7-day schedules), remote control through a WiFi smartphone app, and works with Amazon Alexa and Google Assistant for hands-free voice control.

The WITH3 is manufactured by SunAura Thermal, an ISO-managed factory in Qingdao, China, with more than 17 years of OEM/ODM experience supplying heating controls to distributors and installers in 50+ countries. Every unit is tested before shipment and carries FCC, CE and WEEE compliance. For homeowners, heating installers and HVAC distributors, the WITH3 combines the reliability of a purpose-built boiler thermostat with the convenience of a modern smart home device.

Key Features

• True wireless boiler control — the room thermostat talks to the wall-hung boiler over a 433 MHz RF link; no thermostat wire between the room unit and the receiver.
• Two-part set, simple retrofit — battery-powered transmitter plus mains-powered receiver; the receiver connects to the boiler’s existing on/off thermostat terminals (dry contact).
• 7-day programming — choose a 5+2, 6+1 or fully independent 7-day schedule, with up to six time periods per day set in the app, so heating follows your weekday and weekend routine.
• Smartphone app and voice control — built-in WiFi lets you adjust temperature, programmes and holiday mode remotely; the unit works with Amazon Alexa and Google Assistant for voice commands.
• Rotary knob operation — a large dial adjusts the set temperature and screen brightness; big backlit digits remain readable at a glance, day or night.
• Battery or USB power — the room unit runs on three AA (No.5) batteries for total placement freedom, and can also be kept topped up over USB Type-C DC 5 V.
• ECO and antifreeze modes — ECO setback lowers consumption, while antifreeze mode protects the heating system and pipes while the home is empty.
• Child lock and temperature limits — a lock icon prevents accidental changes, and configurable upper/lower temperature limits guard against overheating or misuse.
• Calibratable accuracy — display resolution of 0.1 °C with a 0.5 °C set resolution, and temperature/humidity calibration up to ±9 °C to match real room conditions.

Display & Icon Guide

The WITH3 uses a backlit VA LCD that presents the whole heating state at a glance. The large number on the left of the screen is the ROOM TEMP — the measured indoor air temperature — while the target value is always shown as the set temperature so the two are never confused. A heating-on icon lights when the receiver is calling for heat from the boiler, a battery icon reports the transmitter’s remaining charge, and a WiFi icon confirms the app connection. The week icon indicates the current day, the clock shows the time, and a small weather-style icon and humidity % reading give extra context for comfort. A child-lock icon confirms that the buttons are locked.

Operation is deliberately simple: turn the rotary knob to raise or lower the set temperature, and use the menu to switch between manual and programme mode. You can toggle the temperature unit between °C and °F, adjust the backlight brightness, turn the key beep on or off, and choose the internal (IN) sensor. The displayed temperature resolves to 0.1 °C, the set step is 0.5 °C, and both temperature and humidity can be calibrated by up to ±9 °C so the reading matches a trusted reference thermometer wherever the unit happens to be mounted.

Technical Specifications

Applications

The WITH3 is a wireless room thermostat for any home or light-commercial wet heating installation where the boiler and the control point are in different rooms:

• Wall-hung gas boilers — combi, system and conventional boilers with standard on/off thermostat terminals.
• Radiator wet heating — hydronic radiator circuits zoned by a single wireless room stat.
• Underfloor water heating — warm-water underfloor loops controlled through the boiler by the RF set.
• Retrofit and renovation projects — adding smart control to an existing boiler without chasing walls for thermostat cable.
• Apartments and flats — multi-storey homes where running wired control cable between floors is impractical.
• Holiday homes and rentals — remote app control and antifreeze protection while the property is unoccupied.

Installation

Installing the WITH3 is faster than a conventional wired room stat because the only wiring is at the boiler end:

1. Mount and wire the receiver — fix the RF receiver beside or near the wall-hung boiler and connect its two terminals to the boiler’s standard on/off (room thermostat) inputs, following the wiring diagram in the user guide. Wiring should be carried out by a qualified heating engineer.
2. Power the receiver — supply the receiver from its rated supply; the LED confirms it is ready to pair.
3. Pair the transmitter — put the receiver into pairing mode, then trigger pairing on the room thermostat; the two units handshake over 433 MHz and the link is confirmed. No physical wire runs between them.
4. Place the room unit — slot three AA batteries (or connect USB Type-C power) and position the thermostat on an interior wall at roughly eye level, away from direct sunlight, draughts or heat sources.
5. Set the programme — choose 5+2, 6+1 or 7-day scheduling on the unit or in the app, adjust ECO and antifreeze settings, and the boiler will now follow your schedule automatically.

The link is rated up to 300 m in open field, which translates to roughly 100 m of line-of-sight range inside typical homes — enough to cover an apartment or multi-storey house even when the boiler sits in a kitchen or utility room. Standard accessories with every set include the host units, the signal line, a USB charging cable, fixing screws, the certificate of conformity and the user guide. Our engineers are available by WhatsApp for remote commissioning support.

Compatibility with SunAura Heating Systems

The WITH3 pairs naturally with the full SunAura wet heating offering: wall-hung boiler packages, radiator circuits and warm-water underfloor systems. Where a SunAura installation already includes an electric heating element or hybrid set, the WITH3 receiver switches the boiler by a clean dry contact, so one wireless room control can govern the whole hydronic circuit. When you buy a boiler-based heating package from SunAura, we can pre-configure the temperature limits, ECO setback and default weekly schedule to match your project, and supply the boiler, receiver, room thermostat and accessories as one factory-sourced package under a single warranty. Because the receiver is a universal on/off contact, the WITH3 also retrofits onto most third-party wall-hung boilers fitted with standard thermostat terminals.

Quality, Certification & Support

SunAura Thermal has manufactured heating controls and heating products since 2008 from our Qingdao factory, operating with ISO-style quality management and in-line testing on every thermostat batch. The WITH3 carries FCC, CE and WEEE compliance and an IP20 ingress rating, built on a flame-retardant PC/ABS V0 housing. We support distributors and OEM customers with private-labelled branding, custom schedules, packaging design and drop-ship logistics to more than 50 countries.

FAQ

1. How do I pair the wireless thermostat with the receiver?

Put the receiver into pairing mode (usually a short press of its pairing button until the LED flashes), then start pairing from the room thermostat’s menu. Within a few seconds the two units handshake over 433 MHz and the link LED stays on — no physical wire between the room unit and the boiler is ever needed.

2. How is the receiver wired to my wall-hung boiler?

The receiver has a standard dry-contact output that connects to the boiler’s on/off room-thermostat terminals, exactly like a conventional wired room stat. The wiring should be done by a qualified heating engineer following the diagram supplied in the user guide; do not connect mains voltage directly across the contact.

3. How is the room thermostat powered?

The transmitter runs on three AA (No.5) batteries, which gives you total placement freedom, and it can also be kept powered or topped up through its USB Type-C DC 5 V input. The receiver is powered from its rated supply (AC 90–240 V, 50/60 Hz) near the boiler.

4. What range can I expect from the 433 MHz wireless link?

The link is rated up to 300 m in open field. Inside a typical home this translates to around 100 m of line-of-sight, which is enough for most apartments and multi-storey houses. Walls, floors and metal boiler casings reduce range, so keep the receiver as open and central as practical.

5. How do I set up the 7-day heating programme?

Choose between a 5+2, 6+1 or full 7-day schedule in the menu or app, then set up to six time periods per day, each with its own target temperature. The boiler then heats only when you want it to, switching automatically between comfort and setback temperatures across the week.

6. Is the WITH3 compatible with my wall-hung boiler?

It works with almost any combi, system or conventional wall-hung boiler that has standard on/off (dry-contact) room-thermostat terminals. Because it is a universal contact rather than a proprietary BUS, it also retrofits onto most existing boilers — just confirm your boiler has the two terminals.

7. How do I connect the thermostat to the app and voice control?

After the RF pair is working, add the thermostat to the WiFi network through the companion smartphone app. The WITH3 then works with Amazon Alexa and Google Assistant, so you can check or change the temperature remotely and control it by voice.

8. What warranty and after-sales support do I get?

Every WITH3 includes a 2-year warranty and direct after-sales support from SunAura — spare parts, pairing help and commissioning guidance by WhatsApp, in English, German, French and Chinese.

Looking for a wireless thermostat for wall-hung boiler without wiring? The WITH3 set is engineered exactly for that retrofit job: a 433 MHz RF boiler thermostat retrofit that pairs a battery-powered room thermostat for combi boiler use with a compact wired receiver, so you avoid chasing walls for thermostat cable while still getting app scheduling, ECO setback and frost protection. If you are comparing wireless boiler controls, the notes below explain how to order the WITH3 as a single set, as a distributor stock item or as an OEM private-labelled package.

How to Buy from SunAura Factory

SunAura Thermal supplies the WITH3 RF wireless thermostat directly from our Qingdao factory to installers, HVAC distributors and project buyers in 50+ countries. Whether you need one set for a renovation, a carton of stock for your trade counter or a container of private-labelled units for your brand, the order process is straightforward: send us your receiver choice (plug-in or wall-mounted), the quantity and the destination port, and we will come back with a same-day quotation that includes EXW or FOB pricing, lead time and FCC, CE and WEEE certification documents. Wholesale price breaks apply at higher volumes, and free samples can be arranged for serious trade customers covering the sample and courier cost. OEM/ODM and private label orders are supported with custom housing colour, branded packaging, pre-configured weekly schedules and drop-ship logistics. MOQ and pricing depend on model and quantity — send your enquiry for a same-day quotation.

To start an order, contact our sales team with your quantity and destination, or message us on WhatsApp for the fastest reply. You can also browse the full range on our thermostats and controls category page, compare the WITH3 with our programmable wired boiler thermostat, the 7-day hydronic heating room thermostat and the dial-style WiFi boiler thermostat, and read more about typical retrofit jobs on the applications page. Common ordering and installation questions are also gathered on the FAQ page.

FAQ (continued)

9. Can I buy the WITH3 as a wholesale or private-labelled set?

Yes. SunAura ships the WITH3 to distributors and OEM partners worldwide with wholesale price breaks, EXW or FOB quotations, FCC/CE/WEEE certification documents and optional private-labelling on the housing and packaging. MOQ and lead time depend on quantity — send your enquiry through the contact page for a same-day offer.

10. Is the WITH3 a good retrofit choice for a listed or rented property?

Because the only wiring is at the boiler end and the room unit runs on three AA batteries or USB Type-C power, the WITH3 is a strong choice for retrofit homes, flats and rentals where chasing walls for thermostat cable is not allowed. The receiver is a universal dry contact, so it also retrofits onto most third-party wall-hung boilers with standard on/off terminals.

11. What accessories and documents ship with each set?

Every WITH3 set includes the room thermostat, the chosen receiver (plug-in or wall-mounted), the signal line, a USB charging cable, fixing screws, the certificate of conformity and the multi-language user guide. Our engineers are available by WhatsApp for remote pairing and commissioning support in English, German, French and Chinese.

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