ATTACK Cassette Fan Coil Unit FCU - C 6 (9.0/5.8 kW, DC motor)

Product detailed description

ATTACK Cassette fan-coil unit FCU - C 6 (9.0/5.8 kW, DC motor) is a cassette (ceiling-recessed) fan-coil (fan convector) unit from the FCU - FCU - C 6 series, designed to distribute heat and cold from a heat pump (e.g. ATTACK Inverter R32 Air/Water) directly into residential or commercial spaces. The unit achieves a cooling output of approx. 9.0 kW and a heating output of approx. 5.8 kW, and is powered by a modern direct current (DC/EC) fan motor with smooth speed control.

Key features

• cassette (ceiling-recessed) installation - mounted into the ceiling, typically into a 600x600 mm module, with air distribution into the room via a four-way (or one-way) discharge grille and central intake - suitable especially for office, commercial and residential spaces with a suspended ceiling where a hidden, aesthetic installation is required
• Cooling output approx. 9.0 kW, heating output approx. 5.8 kW (at rated conditions)
• DC (EC) fan motor - low power consumption, quiet and smoothly adjustable operation
• Built-in condensate collection tray with drain connection for cooling mode
• Replaceable/washable air filter that captures dust and coarse impurities
• Rated air flow rate approx. 1300 m³/h at the highest fan speed
• Option of independent room control using a thermostat/controller and a motorised valve on the water supply
• Suitable as a terminal (distribution) element of a heating and cooling system with a heat pump

How a fan-coil unit works

A fan-coil (fan convector) is a water heat exchanger fitted with a fan that blows room air through a finned exchanger. In summer, chilled water from a heat pump operating in cooling mode flows through the exchanger, the air is cooled and dehumidified, and the unit returns it back into the room - the resulting condensate is drained through the collection tray and drain connection. In winter, warm heating water can instead flow through the exchanger, and the unit serves as a supplementary or main heat source for the room, with a faster response than, for example, underfloor heating.

Thanks to the DC (EC) motor, the fan speed can be smoothly adjusted to the current output requirement and to the demand for quiet operation (e.g. in night mode in a bedroom), while keeping the fan's own electricity consumption low.

Overview of the ATTACK FCU fan-coil unit range

The ATTACK FCU range offers cassette (ceiling-recessed) and wall-mounted versions in several output levels, so a suitable unit can be selected for rooms of various sizes. The ATTACK Cassette fan-coil unit FCU - C 6 (9.0/5.8 kW, DC motor) model is part of this range.

Choosing a suitable room and location

When selecting the location of a fan-coil unit, it is necessary to take into account the room's thermal load (floor area, window orientation, glazed areas, number of occupants), a clear air flow path without obstacles (furniture, curtains) and the availability of a water supply and electrical connection. For the cassette version, sufficient clear height above the ceiling must be provided for the unit body and service access, while for the wall-mounted version, placement in the upper third of the wall with a clear view into the room is recommended.

Installation and use

ATTACK Cassette fan-coil unit FCU - C 6 (9.0/5.8 kW, DC motor) connects to the heating/cooling water supply via a G 1/2" threaded connection; we recommend installing shut-off ball valves for servicing purposes and a motorised 2-way or 3-way valve to control the flow according to the room's current thermal load. Condensate drainage must be solved either by gravity flow into the sewer or using a condensate pump if a gravity gradient is not available. The unit's weight is approx. 32.5 kg, with approximate dimensions of 600x600x260 mm (cassette body) + approx. 850 mm of superstructure above the ceiling. Before first start-up, we recommend having the connection checked by a professionally qualified person.

Control and operation options

The unit can be complemented with a wired room controller with a display, a wireless remote control, or integrated into a higher-level building management system. Control generally allows setting the desired temperature, selecting the fan speed level, and switching between heating and cooling mode (for systems with 4-pipe or switchable 2-pipe distribution). The specific type of controller and its functions should be selected according to the heating/cooling system design.

Energy efficiency and operating costs

Thanks to the DC (EC) fan motor, the electricity consumption of the ATTACK Cassette fan-coil unit FCU - C 6 (9.0/5.8 kW, DC motor) itself is significantly lower than with older AC motor types, especially at partial output. Since a fan-coil unit only distributes heat/cold produced by the heat pump and does not generate heat itself, its operating costs consist mainly of the fan's consumption - the actual energy consumption for heating/cooling depends primarily on the efficiency of the connected heat pump.

Practical usage examples

Summer cooling of the living room: The ATTACK Cassette fan-coil unit FCU - C 6 (9.0/5.8 kW, DC motor) connected to an ATTACK Inverter R32 heat pump operating in cooling mode can significantly improve thermal comfort in a room during hot summer months, where underfloor heating alone provides no or only limited cooling effect.

Quick temperature boost in transitional seasons: In spring and autumn, when outdoor temperatures fluctuate, a fan-coil unit provides a faster response to changes in the desired temperature than the more sluggish underfloor heating, which is especially appreciated in rooms with variable occupancy (living room, home office).

Compatibility with ATTACK heat pumps

The ATTACK Cassette fan-coil unit FCU - C 6 (9.0/5.8 kW, DC motor) is designed to work with ATTACK Inverter R32 Air/Water heat pumps, which can supply both chilled and warm heating water needed for the unit's cooling and heating modes. When more fan-coil units are installed in a building, we recommend connecting them via a hydraulic manifold or a buffer/balancing tank (e.g. ATTACK AK ANTIKOR), which stabilises the flow and protects the heat pump against unwanted compressor cycling when several circuits open/close simultaneously.

Air quality and filtration

Intake air passes through a replaceable/washable filter before reaching the exchanger, which captures coarser dust and particles, protecting the finned exchanger from clogging and extending the interval between deep cleanings of the unit. When operating in cooling mode, the room air is also partially dehumidified, which in the summer months contributes to a better sense of thermal comfort even at the same air temperature. For increased air quality requirements (allergy sufferers, dustier environments), a finer supplementary filter can also be considered if the given model and controller allow it.

Safety and installation notes

The electrical connection of the unit (fan, and if applicable the condensate pump) must be carried out by a professionally qualified person in accordance with applicable electrotechnical standards. Condensate drainage must be routed with a gradient away from living spaces, or via a functional condensate pump, to prevent water leaking into the building structure. Before first start-up, we recommend performing a pressure test of the water circuit.

Ecological and sustainability aspect

Thanks to the DC (EC) fan motor, the ATTACK Cassette fan-coil unit FCU - C 6 (9.0/5.8 kW, DC motor) consumes less electricity than comparable versions with an older AC motor, especially when operating at partial output. Since the unit only distributes heat/cold and does not generate it (this is done by the connected heat pump), its ecological benefit lies primarily in the efficient use of already produced energy without unnecessary losses.

Delivery and handling

The product is delivered by pallet freight, typically within a few business days of ordering (we will confirm the exact delivery date after receiving your order, as some models are manufactured or assembled to order). Given the product's weight (approx. 32.5 kg), we recommend having suitable handling equipment available when receiving the shipment (pallet truck, or a second person), and checking the packaging for damage upon receipt in order to preserve any claim for transport damage.

About the manufacturer ATTACK

ATTACK, s.r.o. is a Slovak manufacturer of heating and cooling technology, which complements its portfolio of ATTACK Inverter R32 heat pumps with related accessories including FCU fan-coil units, buffer tanks and DHW cylinders, in order to offer customers a complete heating and cooling solution from a single source.

Technical parameters

Note: dimensions, weight and air flow rate are approximate estimates for this FCU model; please verify the exact values in the manufacturer's current technical data sheet or request them when ordering.

Frequently asked questions

How does a fan-coil unit work in combination with a heat pump?

A fan-coil unit is a water heat exchanger with a fan that takes cold or warm water from a heat pump (e.g. ATTACK Inverter R32) and delivers it to the space through intensive air flow - it cools in summer and can provide supplementary heating in winter. It is therefore a terminal (distribution) element of the heating/cooling system, not a standalone heat source.

Does condensate form during cooling, and how is it drained?

Yes, during cooling mode, moisture from the air condenses on the cooling exchanger. The unit is equipped with a condensate collection tray with a drain connection, which is connected to drainage by gravity or via a condensate pump if a gravity gradient is not available.

Why does the unit have a DC (EC) motor, and what are the benefits?

Compared to a conventional AC motor, a direct current (DC/EC) fan motor offers smooth speed control, significantly lower electricity consumption and quieter operation, which is a significant advantage for year-round fan-coil operation in residential spaces.

What is the difference between the cassette and wall-mounted versions?

The cassette (C) version is mounted into the ceiling (usually a 600x600 mm module) and distributes air into the room via 4-way (or 1-way) grilles, which is suitable for larger rooms and where a hidden installation is required. The wall-mounted (W) version is mounted on the wall similar to a classic split air-conditioning unit and is simpler to install and to maintain the filter.

Can a single fan-coil unit be controlled independently from the rest of the heating system?

Yes, the units are typically fitted with their own room thermostat/controller (wired or wireless) and a motorised 2-way or 3-way valve on the water supply, so the temperature in a given room can be controlled independently of other circuits.

Is a buffer or balancing tank required before the fan-coil units?

Connection via a hydraulic manifold/balancing (buffer) tank is recommended, for example from the ATTACK AK ANTIKOR range, which stabilises the flow and temperature of the water supplied to the individual fan-coil units and protects the heat pump compressor against frequent switching.

How noisy is the unit, and can it be adjusted?

Thanks to the DC motor, several fan speed levels can be smoothly set - at the lowest level, operation is very quiet, suitable for example for a bedroom, while at the highest level the maximum declared cooling/heating output is achieved.

Can the unit be connected to a central control system (BMS) or an app?

Yes, most fan-coil unit controllers support connection to a bus (e.g. Modbus) or integration into a higher-level building management system (BMS), or via a gateway to a mobile app. The specific options depend on the type of controller chosen, which must be purchased separately according to the project design.

How often does the filter need to be cleaned or replaced?

We recommend checking and cleaning (or replacing) the air filter at least twice a year, more often when operating in dustier environments. A clogged filter reduces the unit's air flow rate and can increase its noise level.

Can a fan-coil unit fully replace radiators, or does it only supplement heating?

In practice, fan-coil units are used in both ways - as a supplementary quick source of heat/cold alongside underfloor heating (especially for summer cooling, which underfloor heating alone does not provide), or as the main heating and cooling element in a room. The choice depends on the overall design of the building's heating/cooling system.

Warranty and service

This ATTACK brand product is covered by a standard warranty period of 24 months from commissioning, but no more than 30 months from the date of dispatch from production. For selected products, and when commissioning is registered by an authorised service technician, an extended warranty can also be arranged - please check the specific conditions when ordering or with our sales department. Service and spare parts are provided by the network of authorised ATTACK service partners in Slovakia, and spare parts are normally kept in stock.

Before commissioning, we recommend having the connection and system filling checked by a professionally qualified person (heating engineer/service technician), in order to meet the conditions for the full warranty period.

Summary

ATTACK Cassette fan-coil unit FCU - C 6 (9.0/5.8 kW, DC motor) - a cassette (ceiling-recessed) fan-coil unit with a DC motor, cooling output approx. 9.0 kW and heating output approx. 5.8 kW, designed to distribute heat and cold from the ATTACK Inverter R32 heat pump into residential and commercial spaces.