Baxi Heating Controls

Baxi sells heating controls as part of a wider domestic heating range, and the current line-up runs from simple wireless thermostats to the AmbiZen Smart Control launched in May 2026. The controls are made to work with Baxi's own boilers, cylinders and air source heat pumps, and the maker states they "help you comply with the latest Building Regulations"¹. Baxi describes its professional catalogue as covering "a wide range of models and outputs of products, flues, controls and accessories" for domestic heating installations².

The practical question for a household is what the controls do for independence. A Baxi control that schedules and modulates a Baxi boiler locally keeps the household in charge of when heat is produced. The AmbiZen Smart Control adds remote operation through the My Baxi app, and can be linked to Google Assistant or Amazon Alexa for hands-free control³. That is convenience bought with a dependence: the app, the home broadband connection and the manufacturer's servers all sit between the householder and the boiler.

This page sets out what Baxi's controls cover, how the range divides between smart, wireless and connected products, what the flagship models do, how controls relate to Building Regulations, warranty and cost, and where the limits of a manufacturer's control ecosystem lie.

What Baxi heating controls cover, and why they matter

Baxi's control range exists to do three jobs: set when the heating runs, hold a room or system temperature, and, on the more advanced products, report what the system is using. The professional catalogue lists "a range of heating controls" alongside the boilers, cylinders and heat pumps they serve¹. The AmbiZen Smart Control is the newest and most capable of them, and the wireless single- and twin-channel controls sit below it as "quick to install options for any installation"³.

The reason controls matter beyond comfort is regulatory. Baxi states that its heating controls "help you comply with the latest Building Regulations"². That is a maker's framing of a legal position: since the Boiler Plus standards took effect in England on 6 April 2018, boiler replacements have required additional controls, and for gas combi boilers a further energy efficiency measure as well, which the Chartered Institute of Plumbing and Heating Engineering notes makes replacements more expensive⁷. Controls are therefore not an optional extra bolted onto a new boiler; they are part of what makes the installation compliant.

For a household, the control layer is also the point at which a heating system stops being a purely local machine. A wired thermostat and a programmer work without any network. A smart control that schedules from a phone, reports energy use and accepts voice commands depends on a chain of third parties. Baxi's own range spans both ends of that spectrum, which is why the choice of control matters as much as the choice of boiler.

The range: smart, wireless and connected controls

Baxi's controls divide into three broad groups. The first is the smart layer, led by the AmbiZen Smart Control, which is compatible with Baxi air source heat pumps, boilers and cylinders and is operated through the My Baxi app³. The second is the wireless thermostat layer: the OpenTherm RF Thermostat in single-channel form, and the RF Thermostat in twin-channel form. The third is the connected module layer, where Mercurius Connected is factory-fitted to Baxi AquaHeat heat interface units rather than sold as a standalone household control⁸.

The OpenTherm RF Thermostat (Single Channel) is designed for one heating zone, or up to six heating zones with additional Baxi thermostats, and is typically used where a modulating control is wanted⁹. The twin-channel RF Thermostat is aimed at homes with two heating zones, separating the control of two circuits¹⁰. Both are wireless, which removes the need to run new cable through finished walls, and both are Baxi-branded products intended for Baxi systems.

The distinction that matters most for a household is between a control that modulates and one that simply switches. An OpenTherm connection lets the thermostat tell the boiler what flow temperature to produce rather than cycling it on and off at a fixed setting, which is the mechanism behind load compensation and modulation. Baxi states that on named combi boilers, including the Main Eco Compact and Baxi Platinum Compact, "the control is the master when fitted via OpenTherm"⁹. That is a specific wiring and configuration relationship, not a general claim about all Baxi boilers.

AmbiZen Smart Control and Mercurius Connected: the flagship models

The AmbiZen Smart Control is the household-facing flagship. Baxi introduced it on 12 May 2026 as the lead product in a new wireless control range compatible with its air source heat pumps, boilers and cylinders³. Its published features are seven-day scheduling, holiday mode and real-time energy monitoring, all through the My Baxi app, with the option for installers to link it to Google Assistant or Amazon Alexa for hands-free control³. The thermostat connects via the My Baxi app¹, and Baxi lists compatibility with the Baxi Combi 2 ranges, the Baxi Amptec S electric boiler range, Baxi pre-plumbed cylinders and Baxi ASHP Control⁴.

Installation detail is published for the professional market: the gateway receiver wire goes to connection X9 on the main PCB board of the Baxi Combi 2 ranges¹¹. Baxi also notes that "compatibility may vary due to heat pump control"¹¹, which is a caution rather than a blanket statement, and worth checking against the specific heat pump model before assuming the thermostat will drive it.

Mercurius Connected is a different kind of product. It is a factory-fit module for the Baxi AquaHeat heat interface unit, which Baxi describes as the answer for homes fed with heat from a heat network, including communal and commercial premises⁸. The AquaHeat HI/HWI is available in two outputs, with or without a heat meter and with the Mercurius connected module factory fit⁸. Mercurius was launched in the UK in July 2024 as a digital innovation for remote monitoring and optimisation of heat interface units, part of a wider end-to-end heat network service⁸.

The two products therefore answer different questions. AmbiZen is a household control for a home with its own boiler or heat pump. Mercurius is a building-level monitoring module for a flat or premises on a communal heat network, where the household does not own the heat source at all. A resident in a heat network property has no boiler to control and no gas supply of their own; the control they see is a heat interface unit, and Mercurius sits behind it.

How controls help you comply with Building Regulations

Baxi's claim that its controls "help you comply with the latest Building Regulations"² needs unpacking, because the compliance route differs across the UK and the paperwork sits with the householder or their installer, not the control maker.

In England, building regulations approval is handled by contacting a building control body to check the regulations or apply for approval¹². In Northern Ireland, Building Regulations apply to most building work, and an application must be submitted to Building Control Services before the work proceeds; applications are required for new build, extensions and minor work including installing fittings and new heating appliances and systems¹³. In Wales, electrical installation work is checked either through an electrician registered with a competent person scheme or by notifying the building control section of the local authority, and an application should be made if the electrician is not registered or if the householder does the work¹⁴.

The controls themselves sit inside Approved Document L, which governs the conservation of fuel and power in dwellings. Where a building control body is satisfied that work meets the requirements, it issues a completion certificate if it is a building control authority, or a final certificate if it is a registered building control approver¹⁵. For new dwellings, the building control body must be notified once work is complete of as-built performance rates, fabric performance values and the as-built specifications list¹⁶. Following the procedures in PAS 2030/2035: 2019 is one way of demonstrating that suitability has been adequately considered¹⁶.

What this means in practice is that a control's compliance value depends on the whole installation being documented. A thermostat that provides time and temperature control, and on a combi a further efficiency measure, is part of what an installer signs off. The wider regulatory picture, including the differences between the four nations, is set out in Building Regulations for heating controls.

What controls cost and where they fit in a boiler installation

Baxi publishes no list price for its heating controls, and no installed price for a control as a standalone item. Prices for controls are installer-quoted, and the figure that appears in the published record is a general one: the Boiler Plus standards, in force in England since 6 April 2018, mean boiler replacements are more expensive because boilers need additional controls and, for gas combi boilers, a further energy efficiency measure⁷. That is a statement about direction, not an amount.

Where controls sit in an installation is clearer. Baxi's system boilers are described as "super easy to install, compact" with an in-built pump¹⁷, which reduces the external components an installer has to add. The controls then attach to the boiler, either wirelessly or through a wired connection, and on an OpenTherm-compatible combi the thermostat becomes the master control⁹. Baxi's installer network is a postcode search returning local, trained, Gas Safe registered engineers where applicable⁴, and its Baxi Works scheme rewards installations of boilers, cylinders, heat pumps or all of the above².

For a household planning a boiler replacement, the control decision is best made at the same time as the boiler choice, because the two are wired and configured together. A control added later may not achieve the same modulating relationship with the boiler, and the OpenTherm master relationship in particular depends on the boiler model and the wiring at installation. The general cost picture for controls, including the difference between a simple thermostat and a zoned system, is covered in How much do heating controls cost?.

Warranty: why controls are not always covered by the boiler warranty

Baxi's warranty position on controls is narrower than a householder might assume. The boiler warranty "covers the boiler and integrated controls"⁵, and the same wording appears in Baxi's warranty information⁵. That covers a control supplied and fitted as part of the boiler installation. It does not automatically extend to a control added later, or to a control that is not integrated with the boiler.

The conditions attached to the boiler warranty are the ones that catch people out. Registration must happen within 30 days of installation, the installer must complete the Benchmark checklist, and an annual service must be arranged⁶. If the warranty is not registered within that window, it defaults to the standard two years⁶. Baxi also states that if the boiler fails due to an external issue, such as incorrect installation or sludge in the system, this is not covered, and a charge will be incurred for replacing the damaged or blocked components⁵. Repairs needed as a result of sludge in the central heating water are excluded from Baxi warranties¹⁸.

Registration runs through Baxi's warranty pages, which cover boilers and cylinders, and heat pumps separately¹⁹. The information required is the boiler's serial number and the address and postcode where it is installed⁶. Baxi advises the householder to make sure either the installer has registered the warranty or they have done it themselves⁶. The serial number is usually on a sticker either inside the drop down panel or on a pull out tag underneath, and it carries the make, model and age of the boiler²⁰.

Baxi's Care Kits, which are preventive maintenance kits including a combustion chamber door gasket, a flue adapter test point and O-ring among other parts²¹, are optional and not a requirement of the boiler warranty²². Using one does not void the warranty and helps prevent unnecessary repair calls²². The wider question of whether fitting controls yourself affects cover is covered in Does DIY thermostat installation affect my warranty?.

Using Baxi controls with heat pumps and heat networks

Baxi's controls extend beyond gas boilers. The AmbiZen Smart Control is compatible with Baxi air source heat pumps as well as boilers and cylinders³, and Baxi's heat pump accessories are "designed to work with Baxi Air Source Heat Pumps"²³. The Baxi ASHP Control is a separate product used to "set-up and configure our range of Baxi ASHPs"²³, which is a commissioning tool rather than an everyday household thermostat.

Heat pump control has its own logic. Baxi states that air source heat pumps do not burn fossil fuels in order to operate²⁴, and that they come with safety features including pressure relief valves and temperature sensors for protection against overheating and excessive pressure²⁴. Frost protection is built in: Baxi states that air source heat pump frost protection mode can prevent frozen pipes and other potential issues in winter months²⁵. The My Baxi app can be used to make changes to heat pump settings from a smartphone²⁵, which is the same app dependence that applies to the boiler controls.

On heat networks, the control picture is different again. Baxi AquaHeat heat interface units serve homes fed with heat from a heat network, including communal and commercial premises⁸. The unit is available in two outputs, with or without a heat meter and with the Mercurius connected module factory fit⁸. Mercurius Connected was launched in the UK in July 2024 for remote monitoring and optimisation of heat interface units⁸. A household on a heat network does not control the heat source, only the interface unit in the flat, and the connected module is fitted by the network operator rather than chosen by the resident.

Baxi's air source heat pumps are described as suitable for a wide range of properties²⁶, and the company also lists commercial applications for newbuild and retrofit². For a household weighing a heat pump, the control question is whether the thermostat can drive the heat pump's own weather compensation and modulation, which is a different relationship from a boiler's on/off or OpenTherm control. The general principles are covered in Weather compensation controls explained.

What good control means for household energy independence

The independence question for Baxi controls turns on where the intelligence sits. A wireless thermostat and a programmer that talk directly to the boiler keep the household in control: the schedule is held locally, the thermostat works without a network, and the boiler responds to a local signal. The AmbiZen Smart Control adds real-time energy monitoring and remote scheduling through the My Baxi app³, which is genuinely useful information, but it also means the household's ability to see and change its heating depends on a broadband connection, a manufacturer's app and Baxi's servers.

That dependence is not unique to Baxi, and it is not absolute. Local control at the thermostat and at the boiler continues to work if the internet goes down. What stops is remote scheduling, energy monitoring and any remote diagnostics. The same pattern applies to voice control through Google Assistant or Amazon Alexa³, which adds two more third parties to the chain. The wider trade-off between local control and cloud dependence is set out in Heating controls and energy independence.

On the fuel side, Baxi's range spans gas, LPG and electric. Baxi states that its boilers are designed to work with natural gas or LPG¹⁸, and that electric boilers are an effective option for properties off the mains gas grid, being highly efficient and low maintenance¹⁸. A household on a Baxi electric boiler with a local control has no gas supply dependence, though it remains dependent on the electricity grid and a supplier. A household on a Baxi gas boiler remains on the gas grid and on a gas supplier, with an electrical dependence for ignition, controls and pumping.

Baxi's own reliability record is a factor in how long a control ecosystem stays supported. Which? reports that 83% of Baxi owners told it they are satisfied with their boiler²⁷. Baxi has also expanded its after-sales focus on genuine parts and customer support, supporting a large installed base of residential and commercial heating products across the UK²⁸. That installed base is the reason spare parts and support are likely to remain available, which matters for a control that may need replacing before the boiler does.

For support, Baxi's guidance is to call the heating engineer who installed the boiler or contact Baxi Customer Support to arrange for one of its engineers to visit⁵. Have the boiler's serial number handy when contacting Baxi, whether using the online form or the contact centre⁵. The serial number is usually on a sticker either inside the drop down panel or on a pull out tag underneath²⁰.