ATTACK Cassette Fan-Coil Unit FCU - C 3 (4.7/3.0 kW, DC motor)

Product detailed description

ATTACK Cassette fan-coil unit FCU - C 3 (4.7/3.0 kW, DC motor) is a cassette (ceiling-recessed) fan-coil unit from the FCU - C 3 series, designed for distributing 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 capacity of approx. 4.7 kW and a heating capacity of approx. 3.0 kW, and is powered by a modern DC (EC) fan motor with continuous 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, retail and residential spaces with a suspended ceiling where hidden, aesthetic installation is required
• Cooling capacity approx. 4.7 kW, heating capacity approx. 3.0 kW (at rated conditions)
• DC (EC) fan motor - low electricity consumption, quiet and smoothly adjustable operation
• Built-in condensate collection tray with drain fitting for cooling mode
• Replaceable/washable air filter that captures dust and larger debris
• Rated air flow rate approx. 750 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) unit for both heating and cooling systems with a heat pump

How a fan-coil unit works

A fan-coil unit is a water-to-air heat exchanger fitted with a fan that draws air from the room through a finned coil. In summer, chilled water from a heat pump operating in cooling mode flows through the coil, the air is cooled and dehumidified, and the unit returns it back to the room - the resulting condensate is drained via the collection tray and drain fitting. In winter, warm heating water can instead flow through the coil, 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 need 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 both cassette (ceiling-recessed) and wall-mounted versions in several capacity levels, allowing you to choose the right unit for rooms of different sizes. The ATTACK Cassette fan-coil unit FCU - C 3 (4.7/3.0 kW, DC motor) model is part of this range.

Choosing the right room and location

When choosing the location for a fan-coil unit, take into account the room's heat load (floor area, window orientation, glazed areas, number of occupants), an unobstructed airflow path (furniture, curtains) and the availability of water and electrical connections. For the cassette version, sufficient clear height above the ceiling must be available for the unit body and for service access; for the wall-mounted version, positioning in the upper third of the wall with a clear view into the room is recommended.

Installation and use

The ATTACK Cassette fan-coil unit FCU - C 3 (4.7/3.0 kW, DC motor) is connected to the heating/cooling water piping via a G 1/2" threaded connection; we recommend installing shut-off ball valves for servicing and a motorised 2-way or 3-way valve to regulate flow according to the current heat load of the room. Condensate drainage must be handled either by gravity fall to the sewer or by means of a condensate pump if gravity fall is not available. The unit weighs approx. 24.5 kg, with approximate dimensions of 600x600x260 mm (cassette) + approx. 850 mm extension above the ceiling. Before first start-up, we recommend having the connection checked by a qualified professional.

Control and operation options

The unit can be complemented with a wired room controller with a display, a wireless remote controller, or integrated into a building management system. Control typically allows setting of the desired temperature, selection of fan speed, and switching between heating and cooling mode (in systems with 4-pipe or switched 2-pipe distribution). The specific type of controller and its functions should be chosen 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 3 (4.7/3.0 kW, DC motor) itself is significantly lower than with older AC motor types, especially at partial load. Since the fan-coil unit only distributes heat/cold generated by the heat pump and does not produce heat itself, its operating costs mainly consist of the fan's electricity consumption - the actual energy consumption for heating/cooling depends primarily on the efficiency of the connected heat pump.

Practical use cases

Summer cooling of a living room: The ATTACK Cassette fan-coil unit FCU - C 3 (4.7/3.0 kW, DC motor) connected to an ATTACK Inverter R32 heat pump operating in cooling mode can significantly improve thermal comfort during hot summer months in rooms where underfloor heating alone provides no or only limited cooling effect.

Fast heat-up during transitional seasons: In spring and autumn, when outdoor temperatures fluctuate, the 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 3 (4.7/3.0 kW, DC motor) is designed to work with heat pumps from the ATTACK Inverter R32 Air/Water range, which can supply both chilled and warm heating water needed for the unit's cooling and heating modes. When installing multiple fan-coil units 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 from unwanted compressor cycling when multiple circuits open/close simultaneously.

Air quality and filtration

The intake air passes through a replaceable/washable filter before contact with the coil, which captures coarser dust and debris particles, protecting the finned coil from fouling and extending the interval between deep cleanings of the unit. When operating in cooling mode, the air in the room is also partially dehumidified, which contributes to a better sense of thermal comfort in summer months 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 condensate pump if applicable) must be carried out by a qualified professional in accordance with applicable electrotechnical standards. Condensate drainage must be routed with a fall 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 3 (4.7/3.0 kW, DC motor) consumes less electricity than comparable versions with an older AC motor, especially when operating at partial load. Since the unit only distributes heat/cold rather than producing it (this is done by the connected heat pump), its ecological benefit lies mainly in the efficient use of already generated energy without unnecessary losses.

Delivery and handling

The product is delivered on a pallet, usually within a few working 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. 24.5 kg), we recommend arranging suitable handling equipment (pallet truck, or a second person) when receiving the shipment, and checking that the packaging is intact 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 fan-coil units from the FCU range, buffer tanks and domestic hot water 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 model in the FCU range; please verify 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 together with a heat pump?

A fan-coil unit is a water-to-air heat exchanger with a fan that receives cold or warm water from a heat pump (e.g. ATTACK Inverter R32) and transfers it to the space through intensive air circulation - cooling in summer, and possibly supplementing 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, in cooling mode, moisture from the air condenses on the cooling coil. The unit is equipped with a condensate collection tray with a drain fitting, which is connected to drainage either by gravity or via a condensate pump if gravity fall is not available.

Why does the unit have a DC (EC) motor and what is the benefit?

Compared to a conventional AC motor, a 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 hidden installation is required. The wall-mounted (W) version is mounted on the wall similarly to a classic split air-conditioning unit and is easier to install and maintain (filter access).

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 the given room can be regulated independently of other circuits.

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

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

How noisy is the unit and can it be regulated?

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

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

Yes, most fan-coil unit controllers support connection to a bus system (e.g. Modbus) or integration into a building management system (BMS), or via a gateway to a mobile app. The specific options depend on the chosen controller type, 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 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 both ways - as a supplementary fast heat/cold source alongside underfloor heating (especially for summer cooling, which underfloor heating alone does not provide), or as the main heating and cooling element in the room. The choice depends on the overall design of the building's heating/cooling system.

Warranty and service

This ATTACK product is covered by a standard 24-month warranty period 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, with spare parts commonly kept in stock.

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

Summary

ATTACK Cassette fan-coil unit FCU - C 3 (4.7/3.0 kW, DC motor) - a cassette (ceiling-recessed) fan-coil unit with DC motor, cooling capacity approx. 4.7 kW and heating capacity approx. 3.0 kW, designed for distributing heat and cold from the ATTACK Inverter R32 heat pump into residential and commercial spaces.