Product detailed description
What does the Buderus MX400 mixing control module do
In larger heating systems where multiple heating circuits with different temperature requirements are connected to a single heat source (for example a Logamax or Logano condensing boiler) – typically underfloor heating requiring a lower flow water temperature of around 30–40 °C and a radiator circuit requiring a higher temperature of around 50–70 °C – it is not enough to control just one shared circuit. Each such circuit needs its own mixing valve assembly and its own control module, which independently mixes hot water from the boiler with the (cooler) return water from the circuit so that the temperature at the inlet of that circuit exactly matches the current heat demand and the set weather-compensation curve.
The MX400 module is exactly this kind of expansion module for a mixing circuit for the Buderus Logamatic control system. It communicates over the EMS bus with the boiler's main controller and with the room controller, measures the supply water temperature using a sensor, controls the circulation pump of the given circuit, and operates the mixing valve actuator so that the resulting temperature precisely matches the needs of the specific heating zone. This makes it possible to connect several circuits with different characteristics to a single heat source (for example underfloor heating on the ground floor and radiators upstairs) and operate each of them at the optimal temperature, which saves energy and increases living comfort.
Difference between set configurations
The MX400 module is always supplied in combination with a room controller, which serves as the higher-level control unit and user interface for the whole system. Buderus offers two different sets depending on the level of control and type of communication the customer needs.
Set MX400, RC120RF combines the MX400 module with the wireless room controller Logamatic RC120 RF. The letters "RF" (radio frequency) denote wireless radio communication between the room unit and the boiler without the need to run cabling – an ideal solution for renovations or situations where running additional cables would mean demolishing and interfering with already finished surfaces and floors. The RC120 RF offers simpler, clear control with a display and basic time programming and temperature setting functions, communicating wirelessly with the MX400 module installed near the boiler.
This configuration is typically more affordable and faster to install where the full functionality of the RC310 touchscreen display is not required – for example as an additional controller for a second, less frequently used zone of the house (such as a guest room, a granny flat, or a basement), where a basic wireless temperature setting without an advanced graphical interface is sufficient.
What's included in the set
- Logamatic RC120 RF (7738112945) – 1 pc
- MX400 module (7738113982) – 1 pc
Typical use cases
The MX400 module is most often used in new buildings and renovations combining underfloor heating and radiators, in houses with an extension or attic added later to the original heating system, or in systems where the temperature of a swimming pool heating circuit, ventilation system, or other specific heat consumer needs to be controlled independently of the main heating circuit of the house.
Thanks to the modular architecture of the Logamatic system, it is possible to start with a simple single-zone solution and add the MX400 module at any later time, once the need for a separately controlled zone arises – for example when finishing an attic or converting a garage into living space. We recommend having the module's installation and connection to the system carried out by an authorized Buderus service technician, who will also configure the appropriate weather-compensation curve and mixing circuit parameters according to the type of heating elements in the given zone.
Frequently asked questions
Can I connect the MX400 module to any Buderus boiler?
The MX400 module is designed for systems with the EMS communication bus (EMS 2 / EMS plus), which is used by modern Buderus Logamax and Logano boilers with Logamatic control. Before purchasing, we recommend verifying compatibility with the specific model and year of manufacture of your boiler, or consulting with an installation company.
How many mixing circuits can I create this way?
The Logamatic system allows several MX400 modules to be connected, each for a separate mixing circuit – the exact maximum number depends on the specific main boiler control unit, so we recommend consulting a technician when designing a system with multiple heating zones.
Do I also need to purchase a temperature sensor and valve actuator with the MX400?
Yes, for full functionality of the mixing circuit, in addition to the MX400 module you also need a supply temperature sensor and a motorized actuator for a three-way or four-way mixing valve – these components are not included in this package and it is advisable to order them together with the set if they are not already installed in the system.
What is the difference between the RC310 and RC120RF in terms of comfort?
The RC310 offers a color touchscreen display, internet connection and a mobile app, advanced programming, and graphical overviews of temperature history. The RC120RF is a simpler wireless controller without internet connectivity, focused on basic time and temperature control, with the advantage of completely cable-free installation.
Can I later switch from the RC120RF to the RC310, or vice versa?
Controllers can be replaced within the Logamatic system, but keep in mind that the RC310 requires a wired connection (or a communication module), while the RC120RF works wirelessly – so a change may require additional cable installation or, conversely, its removal.
Does the MX400 module require its own power supply?
Yes, the module is connected to a power supply as well as to the EMS bus towards the boiler – the exact wiring and location (usually in a distribution box near the boiler or in a separate mounting box) is determined by the project documentation or the installation technician.
Warranty
Buderus products are covered by a warranty in accordance with the seller's general terms and conditions and the warranty conditions of the manufacturer Bosch Thermotechnik GmbH. You can find the exact warranty period and conditions for making a claim in the attached warranty documentation for the product, or request it from our customer service before purchase.
