ATTACK Wall-mounted fan-coil unit FCU - W 3 (4.1/2.7 kW)

Product detailed description

ATTACK Wall-mounted fan-coil unit FCU - W 3 (4.1/2.7 kW) is a wall-mounted fan-coil unit from the FCU - W 3 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 capacity of approx. 4.1 kW and a heating capacity of approx. 2.7 kW, and is driven by a modern direct current (DC/EC) fan motor with smooth speed control.

Key features

• wall-mounted installation - installed directly on the wall similar to a classic wall-mounted (split) air conditioning unit, air is drawn in from the front/top and blown into the room through adjustable louvers - suitable where there is no suspended ceiling available or where simpler installation and filter maintenance is required
• Cooling capacity approx. 4.1 kW, heating capacity approx. 2.7 kW (at rated conditions)
• DC (EC) fan motor - low electricity consumption, quiet and smoothly controllable operation
• Built-in condensate collection tray with drain outlet for cooling mode
• Replaceable/washable air filter capturing dust and coarse particles
• Rated air flow of approx. 600 m³/h at the highest fan speed
• Option for independent room control using a thermostat/controller and motorized 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 heat exchanger fitted with a fan that draws room air through a finned coil. In summer, chilled water from the heat pump operating in cooling mode flows through the coil, the air is cooled and dehumidified, and the unit returns it to the room - the resulting condensate is drained via the collection tray and drain outlet. 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 as well as 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 output levels, allowing you to choose a suitable unit for rooms of different sizes. The ATTACK Wall-mounted fan-coil unit FCU - W 3 (4.1/2.7 kW) model is part of this range.

Choosing a suitable room and location

When selecting the location for a fan-coil unit, consider the room's heat load (area, window orientation, glazed surfaces, number of occupants), an unobstructed airflow path (furniture, curtains) and access to the water supply and electrical connections. With the cassette version, sufficient clear height above the ceiling must be available for the unit body itself and for service access, while with the wall-mounted version it is best to install it in the upper third of the wall with an unobstructed view into the room.

Installation and use

The ATTACK Wall-mounted fan-coil unit FCU - W 3 (4.1/2.7 kW) connects to the heating/cooling water supply via a G 1/2" threaded connection; we recommend fitting shut-off ball valves for servicing and a motorized 2-way or 3-way valve to regulate flow according to the current heat load of the room. Condensate drainage must be provided either by gravity fall into the drainage system or using a condensate pump if a gravity fall is not available. The unit weighs approx. 13.5 kg, with approximate dimensions of 900x195x600 mm (W×D×H, estimate). Before first start-up, we recommend having the connection checked by a qualified professional.

Control and operation options

The unit can be fitted with a wired room controller with a display, a wireless remote control, or integrated into a higher-level building management system. Control typically allows setting the desired temperature, selecting the fan speed, and switching between heating and cooling mode (in systems with a 4-pipe or switched 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 Wall-mounted fan-coil unit FCU - W 3 (4.1/2.7 kW) itself is significantly lower than with older types using an AC motor, especially at partial output. Since a fan-coil unit only distributes heat/cold generated by the heat pump and does not produce heat itself, its operating costs consist mainly 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 examples

Summer cooling of a living room: The ATTACK Wall-mounted fan-coil unit FCU - W 3 (4.1/2.7 kW), connected to an ATTACK Inverter R32 heat pump operating in cooling mode, can significantly improve thermal comfort during hot summer months in a room where underfloor heating alone does not provide any, or only limited, cooling effect.

Fast heat boost during 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 sluggish underfloor heating, which is especially appreciated in rooms with variable occupancy (living room, home office).

Compatibility with ATTACK heat pumps

The ATTACK Wall-mounted fan-coil unit FCU - W 3 (4.1/2.7 kW) is designed to work with ATTACK Inverter R32 Air/Water heat pumps, which can provide both chilled and heated 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 stabilizes flow and protects the heat pump from unwanted compressor cycling when multiple circuits open/close simultaneously.

Air quality and filtration

Before coming into contact with the coil, the intake air passes through a replaceable/washable filter, which captures coarser dust and particles, protecting the finned coil from clogging and extending the interval between deep cleanings of the unit. Additionally, during cooling mode operation, the air in the room is 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 additional filter can also be considered, if the given model and controller allow it.

Safety and installation notes

The unit's electrical connection (fan, and possibly condensate pump) must be carried out by a qualified professional in accordance with applicable electrical standards. Condensate drainage must be routed with a fall away from living spaces or via a working 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 Wall-mounted fan-coil unit FCU - W 3 (4.1/2.7 kW) 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 provided by the connected heat pump), its environmental benefit lies mainly in the efficient use of already generated energy without unnecessary losses.

Delivery and handling

The product is delivered by pallet freight, usually 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. 13.5 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-related damage.

About the manufacturer ATTACK

ATTACK, s.r.o. is a Slovak manufacturer of heating and cooling equipment, which complements its portfolio of ATTACK Inverter R32 heat pumps with related accessories, including FCU series fan-coil units, buffer tanks and domestic hot water cylinders, to offer customers a comprehensive heating and cooling solution from a single source.

Technical parameters

Note: dimensions, weight and air flow are approximate estimates for this FCU series model, please check 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 hot water from a heat pump (e.g. ATTACK Inverter R32) and transfers it into the space through intensive air flow - cooling in summer, and helping to heat in winter. It is therefore a terminal (distribution) element of the heating/cooling system, not a separate heat source.

Does condensate form during cooling and how is it drained?

Yes, during cooling mode, moisture in the air condenses on the cooling coil. The unit is fitted with a condensate collection tray with a drain outlet, which is connected to the drain either by gravity or via a condensate pump if a gravity fall is not available.

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

Compared to a classic AC fan 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 installed in a suspended ceiling (usually a 600x600 mm module) and distributes air into the room through 4-way (or 1-way) grilles, which is suitable for larger rooms and where concealed installation is required. The wall-mounted (W) version is installed on the wall similar to a classic split air conditioning unit and is easier to install and to maintain the filter.

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

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

Is a buffer tank or balancing tank needed upstream of the fan-coil units?

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

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 level, operation is very quiet, suitable for example for a bedroom, while at the highest level the maximum declared cooling/heating capacity 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 system (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 chosen controller type, which must be purchased separately according to the project.

How often should the filter be cleaned or replaced?

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

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

In practice, fan-coil units are used both ways - as a supplementary fast source of heat/cold alongside underfloor heating (mainly 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 carries a standard warranty period of 24 months from commissioning, but no more than 30 months from the date of dispatch from the factory. For selected products, and when commissioning is registered by an authorized service technician, an extended warranty can also be arranged - please check the specific terms when ordering or with our sales department. Service and spare parts are provided by the network of authorized ATTACK service partners in Slovakia, and spare parts are usually in stock.

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

Summary

ATTACK Wall-mounted fan-coil unit FCU - W 3 (4.1/2.7 kW) - a wall-mounted fan-coil unit with a DC motor, cooling capacity of approx. 4.1 kW and heating capacity of approx. 2.7 kW, designed to distribute heat and cold from the ATTACK Inverter R32 heat pump to residential and commercial spaces.