Vaillant aroVAIR VA 2-3VW 035K – set with 3-way switching valve for cassette fan coil 3.5 kW

Product detailed description

Vaillant aroVAIR VA 2-3VW 035K – set with 3-way switching valve for 3.5 kW cassette fan coil

VA 2-3VW 035K is a set with a 3-way switching valve from the accessory range of the Vaillant aroVAIR product line, designed specifically for the smallest power version of the KN series cassette fan coil – the VA 2-035 KN model with an output of approximately 3.5 kW. This set addresses a situation that occurs with certain types of hydraulic connection in 2-pipe combined heating and cooling systems: when the fan coil is connected to a shared circuit through which, depending on the time of year, either warm water flows (during the winter heating season) or chilled water flows (during the summer cooling season), and the system needs to automatically switch the flow direction or connection to the correct branch of the distribution system when switching between seasons or in more complex hydraulic setups.

The 3-way valve functions as a controlled hydraulic component with an actuator (servo drive), which opens and closes the respective water flow paths based on a signal from the fan coil controller or from a higher-level control system. In practice, this allows, for example, the same fan coil to be connected to the boiler's/heat pump's heating circuit in winter and switched to the cooling circuit in summer without the need for manual pipe reconnection or component replacement – the switching is handled automatically by this controlled valve according to the set operating mode.

Technical parameters and set contents

When this set is needed

The 3-way valve set is not a mandatory part of every cassette fan coil installation – its necessity depends on the specific hydraulic connection design of the system. In simple installations, where the fan coil has its own, directly regulated circuit (for example, a separate pump or direct connection to a source with its own flow control for that zone), the 3-way valve may not be required. Conversely, in more complex systems with multiple fan coils on a shared distribution system, when switching between the seasonal heating and cooling mode at the level of the entire system, or when more precise regulation of flow through the fan coil heat exchanger is needed (for example, for hydraulic balancing against other appliances in the system), this set is a recommended or directly necessary component. The decision on whether the 3-way valve is needed should be made by the heating/cooling system designer based on the specific wiring diagram of the given building.

Installation

The set is installed directly into the water piping system near the body of the fan coil unit, according to the exact location specified in the project documentation of the system's hydraulics. The electrical connection of the valve's servo drive to the fan coil's control electronics or to a higher-level control system is carried out by a qualified technician as part of the overall electrical installation of the fan coil system. After installation, it is necessary to functionally test the correct switching of the valve in both operating modes (heating/cooling) and verify that there are no leaks at the connection joints. We recommend entrusting the installation and connection of this set exclusively to a qualified heating and cooling technology specialist, as incorrect connection of the switching valve can cause incorrect operation of the entire circuit or mixing of hot and chilled water between different branches of the system.

Compatibility

This set is designed exclusively for the smallest power class of the KN cassette series – the VA 2-035 KN model (3.5 kW). For larger power classes (5 and 10 kW, models VA 2-050 KN and VA 2-100 KN), a separate set with code 8000022077 (VA 2-3VW 050-100K) is available, structurally adapted to the higher nominal water flow of these more powerful units. When ordering, it is therefore necessary to choose the set that exactly corresponds to the power class of the installed fan coil unit.

Maintenance

The 3-way valve with servo drive is a mechanical-electrical component requiring minimal but regular inspection as part of the overall servicing of the heating/cooling system – an annual check of switching function, joint tightness and the condition of the servo drive is recommended (for example, listening for mechanical sounds during switching, smoothness of movement). Since it is a controlled component with moving parts, its long-term reliable operation also depends on the water quality in the system (the presence of impurities or deposits can over time affect the smoothness of switching), so it is recommended to follow the heat/cold source manufacturer's recommendations regarding treatment and filtration of the circulating water.

How 3-way valves work in heating and cooling technology in general

3-way valves are among the basic hydraulic control components used throughout heating, cooling and sanitary technology – from mixing valves in underfloor heating, through switching valves between the domestic hot water tank and the heating circuit in combi boilers, to precisely this type of application, where the valve switches which branch of the system the water flowing to the fan coil passes through. Physically, it is a body with three water connections (hence the name "3-way") and an internal movable element (a ball or flap) that is rotated or shifted by an electric servo drive, thereby gradually or abruptly changing the ratio in which water flows between the individual connections. In switching (not mixing) mode, which is typical for applications like this set, the valve functions more like a controlled "switch" – it directs the entire flow either to one branch (for example, heating) or to the other (cooling), based on a binary signal from the controller.

The advantage of centralized control using a 3-way valve instead of manual pipe reconnection is primarily the possibility of automation and remote control – a building control system or a simple room controller can, according to the set operating mode (for example, switching from summer cooling to winter heating), automatically switch all connected fan coils at once, without the need for a physical intervention by a service technician with every seasonal change. This is especially useful in systems where the heating and cooling circuits are alternately supplied from the same source (e.g. a heat pump with active cooling function) through partially shared piping.

Why this set is sold separately, not as part of the unit body

Not every cassette fan coil installation requires a 3-way valve – its necessity depends solely on the specific hydraulic wiring diagram of the building, which is designed by the heating and cooling technology designer. In simpler systems, where each fan coil has its own independent circuit with its own circulation pump and direct connection to the source, this function is not required, and installing an additional valve would represent an unnecessary cost. That is why the manufacturer offers the 3-way valve as a separately sold optional accessory, which the customer or installation company orders only in cases where the specific building project actually requires it. This modularity also allows the valve to be added later to an already existing installation, for example if the connection concept is subsequently changed or the fan coil is connected to a new, shared distribution system.

Why order the VA 2-3VW 035K set

If the design of your heating/cooling system with the VA 2-035 KN cassette fan coil includes a shared 2-pipe distribution system for both heating and cooling, or requires automatic switching between modes at the level of an individual fan coil, this set is a necessary component for the correct and automated operation of the entire system. By ordering the original set from the manufacturer instead of a universal valve, you ensure compatibility with the fan coil's control electronics as well as maintaining the warranty conditions for the entire assembly. We recommend consulting the need for this set with the designer or installation company already at the stage of designing the system's hydraulic diagram, so that it is included in the order together with the unit body, cover panel, controller and condensate collection tray, and does not need to be additionally ordered later after discovering that the given wiring scheme requires it.