Ducted Fan Coil Units (FCU) – Dedicated Zone Cooling Units

A compact, insulated casing houses the coil, blower, and drain pan and is designed to fit within the ceiling void.

The FCU cooling coil uses copper tubes and aluminium fins. It is typically available as a 3 row fan coil unit or a 4 row fan coil unit to match the required capacity and chilled water conditions.

The ducted FCU fan is a centrifugal blower that delivers enough pressure to push air through ducts and diffusers. It is available as a 3 speed fan coil unit with an AC motor, or as an EC motor FCU with variable speed.

A washable ducted FCU air filter, often in a separate filter box on the return side, protects the coil and improves indoor air quality.

An insulated, sloped drain pan collects condensate and directs it to the drain connection.

Supply and return plenums connect the unit to the ductwork. Options include a bottom return air plenum FCU or a rear return air plenum FCU, depending on ceiling layout.

A two-way, three-way, or PICV valve with an actuator controls chilled water flow based on the thermostat signal.

A wall thermostat or BMS-connected fan coil controller manages temperature, fan speed, and operating mode.

Horizontal units are the most common type. They are hung in the ceiling void with ducts running sideways to diffusers.

Vertical units are installed inside a wall cavity, riser, or cupboard enclosure, which is useful where ceiling depth is limited, such as in some hotel rooms and apartments.

• Low static FCU: For very short ducts or a direct plenum connection with one or two diffusers.
• Medium static FCU: For moderate duct lengths serving several diffusers.
• High static FCU: For longer duct runs, multiple rooms, or additional filters. A high static ducted fan coil unit provides the extra pressure needed.

When comparing low static FCU vs high static FCU, the choice depends on duct length, number of outlets, and filtration. Correct static selection ensures design airflow at every diffuser.

A 2 pipe ducted fan coil unit has one supply and one return connection. It is the most common choice for cooling-only applications in India.

A 4 pipe ducted fan coil unit has separate chilled water and hot water coils. It works as part of ducted heating and cooling systems, allowing each zone to cool or heat at any time. It is used in hospitals, premium hotels, and cooler regions.

When comparing 2 pipe FCU vs 4 pipe FCU, 2-pipe units are simpler and more economical for cooling-only needs, while 4-pipe units offer year-round flexibility.

AC motor units use fixed multi-speed motors, while EC motor units offer variable speed, lower energy use, and the ability to fine-tune airflow for different duct pressures.

A fresh air duct from a treated fresh air system can be connected to the return plenum, bringing conditioned outdoor air into each zone through the FCU.

Ducted FCUs are commonly available from about 0.75 TR to 5 TR, with airflow of roughly 300 to 2,000 CFM. Exact ranges vary by brand and model.

Ducted FCU sizing depends on area, occupancy, glass exposure, lighting, and equipment load. Compress India carries out heat load calculations for accurate ducted FCU selection for each zone.

FCU external static pressure is the resistance offered by ducts, plenums, filters, and diffusers. Ducted FCU ESP is selected based on the duct layout. Indicative ranges are up to about 30 Pa for low static, around 50–60 Pa for medium static, and around 80–120 Pa or more for high static units, depending on the brand.

Actual capacity depends on chilled water supply and return temperatures. 3-row or 4-row coils are selected to deliver the required output at your building's chilled water conditions.

Ducted FCU airflow and noise vary with fan speed and static pressure. For hotel rooms and bedrooms, a low noise ducted FCU is selected to meet the load at medium speed.

Ducted FCUs need enough ceiling depth for the unit, plenums, ducts, pipe connections, and drain slope. This is typically around 300 mm to 450 mm, depending on the model and duct layout.

Access panels must be provided below the filter, blower, valve kit, and drain connection for routine maintenance.

The unit is hung from the slab using anchor fasteners, threaded rods, and anti-vibration mounts, independent of the false ceiling.

Units, ducts, and diffusers are coordinated with lighting, sprinklers, cable trays, and interior designs to avoid clashes on site.

Supply ducts are sized to deliver design airflow at acceptable velocity and noise levels, with short, direct routes to each diffuser.

A proper return path, through a return duct, ceiling plenum, or a ducted FCU with return air plenum, ensures balanced airflow and prevents pressure problems.

Linear slot diffusers suit premium interiors and long rooms, while square diffusers suit general spaces. Grilles are selected for throw, noise, and appearance.

Supply ducts and plenums are insulated with a vapour barrier to prevent condensation, dripping, and ceiling stains in humid climates.

Correct duct sizing, flexible connectors, acoustic lining, and low air velocities keep ducted cooling quiet inside occupied rooms.

A 2 way valve FCU setup opens or closes chilled water flow based on the thermostat, supporting variable flow systems and saving pump energy.

A 3 way valve FCU setup bypasses water around the coil when cooling is not needed. It keeps system flow constant but offers lower energy savings.

A PICV for ducted FCU combines balancing and control in one valve. A ducted FCU with PICV maintains stable room temperatures and simplifies commissioning.

An FCU balancing valve sets the design flow for each unit, while strainers protect the coil and valve from debris.

Wall thermostats provide accurate temperature sensing and easy control of setpoint, fan speed, and mode.

AC motor units offer three fixed speeds, while EC motor units allow variable speed control for precise airflow and better comfort.

A ducted FCU with BMS integration enables central monitoring, scheduling, setpoint limits, and fault alarms.

In hotel rooms, the ducted FCU can be linked to keycard switches or occupancy sensors to set back temperatures automatically when guests leave.

EC motors use significantly less power, especially at low and medium speeds, where ducted FCUs operate most of the time.

Two-way valves and PICVs enable variable flow chilled water systems, reducing pumping energy and improving chiller efficiency.

Sealed, well-insulated ducts ensure that cooled air reaches the room rather than being lost in the ceiling void.

Setpoint limits, schedules, and occupancy control prevent overcooling. Together, these measures create an energy efficient ducted FCU system.

Only diffusers and grilles are visible, making it the ideal concealed AC unit alternative for premium interiors.

A single ducted FCU can feed several diffusers, or serve adjoining small rooms, through a duct network.

Multiple diffusers spread air evenly, avoiding draughts and hot spots.

Each ducted FCU has its own thermostat and valve for independent zone control.

Treated fresh air can be connected to the return plenum, improving indoor air quality in each zone.

Unlike a concealed split AC, a ducted FCU needs no outdoor unit and no refrigerant piping inside the building.

With the unit located away from the room and no compressor nearby, ducted FCUs deliver very quiet comfort.

Ducted FCUs need a chiller plant or district cooling supply to operate.

Adequate ceiling depth and space for ducts and plenums are essential.

Servicing requires access panels and ceiling access, so these must be planned at the design stage.

Poor insulation or drain faults can cause leaks and ceiling stains. Correct installation and regular maintenance prevent this.

Ductwork, plenums, diffusers, and ceiling coordination make ducted FCUs more expensive to install than hi wall units.

Compress India plans ceiling space, ductwork, access, and drainage from the start, so these limitations are managed smoothly.

A ducted FCU for hotels, usually placed above the entrance or bathroom ceiling, delivers quiet, invisible comfort with keycard integration.

A ducted FCU for offices cools cabins, executive offices, and small workspaces with a clean ceiling finish.

For premium residences on central chilled water or district cooling, a ducted FCU offers the same concealed look as a ducted AC for home, without outdoor units on the facade.

Ducted FCUs provide quiet, draught-free cooling in private rooms and wards, with fresh air supplied through the central system.

Concealed ducted FCUs keep ceilings clean and walls free for displays.

Ducted FCUs deliver even cooling across dining areas while matching the interior design.

Multiple linear diffusers from a ducted FCU give quiet, uniform cooling for meeting rooms and boardrooms. As a commercial ducted FCU, it scales easily across entire buildings.

Blue Star is a well-known Indian HVAC brand offering chilled water ducted fan coil units for commercial and hospitality projects.

Voltas offers ducted FCUs as part of its central air conditioning range.

Daikin offers concealed chilled water fan coil units for hotels, offices, and residences.

Carrier provides ducted fan coil units for chilled water systems in commercial and hospitality buildings.

Trane offers ducted FCUs designed for commercial and institutional buildings with central chilled water plants.

Johnson Controls, through its York range, offers ducted FCUs for central chilled water systems.

Several other ducted FCU manufacturers and specialised suppliers offer quality units. Compress India recommends the most suitable brand and model based on capacity, static pressure, noise, and service support.

Filters should typically be cleaned every two to four weeks, depending on dust levels and usage.

Periodic coil and blower cleaning restores airflow and cooling performance and prevents odours.

The drain pan and drain line are cleaned and flushed to prevent choking, overflow, and ceiling leaks.

Periodic duct and diffuser cleaning removes accumulated dust and improves indoor air quality. We also offer commercial air conditioner cleaning for complete systems.

Control valves and actuators are checked for correct operation, leaks, and response to thermostat signals.

• Comprehensive AMC: Covers scheduled maintenance plus specified spare parts, with predictable annual costs.
• Non-Comprehensive AMC: Covers scheduled maintenance and service visits, with spare parts charged separately.

Causes: blocked drain, poor slope, damaged pipe or duct insulation.

Solution: Clean the drain, correct the slope, and repair insulation and vapour barriers.

Causes: clogged filter, dirty blower, duct leakage, wrong static selection, or closed dampers.

Solution: Clean the filter and blower, seal ducts, rebalance airflow, and review fan speed or static pressure.

Causes: closed or stuck valve, air in the coil, dirty coil, or low chilled water supply.

Solution: Check the valve, vent air, clean the coil, and verify chilled water flow and temperature.

Causes: poor insulation, low supply air temperature, or humid ceiling voids.

Solution: Improve insulation, adjust supply air conditions, and seal ceiling gaps.

Causes: high fan speed, undersized ducts, loose parts, or missing flexible connectors.

Solution: Adjust fan speed, correct duct sizing, tighten components, and add flexible connectors or acoustic lining.

Causes: dirty ducts, dirty coil, or stagnant water in the drain pan.

Solution: Clean ducts, diffusers, coil, and drain pan, and maintain a regular cleaning schedule.

Causes: dirt in the valve, actuator motor failure, or wiring faults.

Solution: Clean or replace the valve and repair or replace the actuator.

Old, noisy, or inefficient units can be replaced with modern ducted FCUs that deliver better cooling, lower noise, and lower energy use.

Switching to EC motor ducted FCUs cuts fan energy and allows precise airflow adjustment for existing ducts.

Upgrading to PICVs and smart or BMS-connected thermostats improves temperature stability and energy savings.

Buildings with many ducted split systems can move to a central chiller with chilled water ducted FCUs, often reusing existing ductwork. This removes outdoor units, reduces refrigerant use, and lowers running costs.

Higher capacity and high static units cost more due to larger coils and blowers. EC motor models are priced higher than standard units but save energy over their life.

Ductwork, plenums, diffusers, insulation, valve kits, chilled water piping, drain lines, and electrical work often form a large share of the total cost of installing ducted air conditioning on chilled water.

Brand, 2-pipe or 4-pipe configuration, static pressure, motor type, duct length, diffuser type, BMS integration, and site conditions all affect the final price.

Share your layout and interior drawings with Compress India to receive an accurate ducted FCU quotation.