Frequently asked questions about fan coils

A fan coil unit (FCU) is an indoor unit with a fan that heats and cools a room using hot or chilled water supplied by a central system (a chiller, boiler or heat pump). It is widely used in offices, hotels, hospitals and homes. For more detail, see our what is a fan coil guide (in Turkish).

We are based in Ankara; we provide on-site service in all 25 districts of Ankara and scheduled service in every region of Turkey.

We are a certified service provider holding a TSE Service Competence Certificate (HYB No: 12850), and we provide independent service for all fan coil brands.

A split air conditioner has its own refrigerant circuit and outdoor unit. A fan coil uses water rather than refrigerant; the chilled or hot water is produced by a central chiller, boiler or heat pump. This makes fan coils a more centralised and manageable solution for large buildings with many rooms.

Yes. It cools when chilled water flows through its coil and heats when hot water flows through it. In a 2-pipe system the whole building runs in one mode at a time; in a 4-pipe system each room can choose heating or cooling independently.

The most common models are cassette, concealed ceiling (ducted), floor-standing (exposed or concealed), wall-mounted and ceiling-mounted units. The choice depends on the suspended ceiling, aesthetic requirements and the heat load.

A fan coil only uses electricity for its fan motor and controls; the heating or cooling is produced by the central system. Consumption depends on the fan speed and motor type. Units with EC motors use noticeably less electricity than conventional 3-speed AC motors.

A fan coil has no compressor; it heats and cools with water supplied by the central system. Units marketed as “inverter fan coils” are generally fan coils with EC motors whose fan speed can be adjusted steplessly.

An EC (electronically commutated) motor is a fan motor whose speed is controlled electronically and steplessly. Compared with a conventional 3-speed AC motor it generally uses less electricity and runs more quietly at low speed; it needs a compatible thermostat that provides a 0–10 V signal.

A fan coil does not burn natural gas itself. For heating it takes hot water from a boiler, combi boiler or heat pump. A “gas fan coil” usually means a fan coil system connected to a gas boiler; for cooling, a chilled water source such as a chiller is needed.

Fan coil noise depends on whether the unit is correctly sized for the room, the fan speed, the motor type and the maintenance condition. A correctly sized unit running at low speed, with an EC motor and a clean blower wheel, runs more quietly. For noise and vibration problems on an existing unit, see the noise and vibration section on our repair page.

In a 2-pipe system the same pipework carries chilled water in summer and hot water in winter, so the building either heats or cools at any one time. A 4-pipe system has separate hot and chilled water circuits, so each room can heat or cool according to its own needs.

At least twice a year, before the cooling and heating seasons. Filters should be checked every 1–3 months depending on how intensively the space is used.

The filter, coil, condensate drain pan, drainage, fan and motor, valve, thermostat and electrical connections are checked and cleaned. You can find the full list on our maintenance page.

It gives you scheduled visits, a standard checklist, per-unit reports and priority in a breakdown, and reduces the cost for buildings with many units.

The filter and coil get dirty, efficiency drops and energy consumption rises. The drain pan and drain line block, leading to water leaks and odours. The motor is overworked and the risk of failure increases. Repairs on neglected units often end up costing more than maintenance would have.

When the cooling or heating season starts, many units come on at once and faults appear all together. A pre-season check tests valves, motors and drainage, reducing surprises during the season.

The unit's location and type, the work carried out, problems found, parts replaced or recommended for replacement, and a recommendation for the next service.

The most common causes are a blocked drain, a full or cracked condensate drain pan, a faulty condensate pump and a drain slope that has been lost. See fan coil leaking water.

It is usually caused by a motorized valve stuck closed, air in the coil, or a heavily fouled filter and coil. The water temperature from the central system should also be checked.

First check the breaker and the controller. If the problem continues, it may be a capacitor or motor failure; contact a technician.

The smell usually comes from moisture and dirt building up in the drain pan and coil. Hygienic cleaning and disinfection are recommended.

Rattling, rubbing, metallic sounds, increasing humming or vibration may indicate a fan wheel, bearing or hanger problem. A gurgling water sound may mean there is air left in the coil.

Possible causes include the thermostat setting, a sensor in the wrong place, a board or power supply problem, or the motor protection circuit tripping. The exact cause is found with measurements.

The filter or coil may be completely blocked, the fan wheel may have come loose on its shaft, or on ducted units the grille or duct connection may have come apart.

On concealed ceiling and cassette units, an overflowing drain pan or sweating valves and pipes can leave water on the ceiling. To find the source, the unit cover should be opened and the drain pan, drainage and valve set checked.

It should be checked every 1–3 months depending on use and how dusty the space is; washable filters should be washed, and worn or disposable filters replaced.

Washing the filter slows down coil fouling but does not stop it. The coil, drain pan and fan assembly also need professional cleaning at regular intervals.

A suitable chemical foam is applied to the coil, left to loosen the dirt, then rinsed with pressurised water that will not damage the fins. The wash water is directed from the pan to the drain or collected.

Fan coils mostly use G2, G3 or G4 class panel filters. If a higher-class filter is wanted, check whether the fan can handle the extra pressure drop.

In addition to the unit itself, access space must be left for maintenance and filter changes. Concealed ceiling units must have a service hatch in the suspended ceiling.

If the water connection points and dimensions match, replacement is usually quick. Where they do not, the connections are adapted and, if necessary, the valve set is renewed.

The room's heat gain/loss, how it is used and the central system's water temperatures are assessed together. The fan coil sizing calculator on our main site (in Turkish) gives an initial idea; the final selection is made after a site survey.

A condensate pump is used where the condensate cannot reach a drain by gravity. On units with a pump, the pump also needs regular maintenance.

Yes. With a networked thermostat or control board, fan coils can be connected to the central building automation system, so you can monitor and manage the whole building from a single screen.

By the number of units, their type, access, level of dirt, parts required and location. The site survey and quotation are free.

Yes. We supply original or technically compatible equivalent parts for motors, valves, thermostats, drain pans, condensate pumps, filters, coils and fans. See our spare parts catalogue.

A photo of the unit's rating plate and of the part to be replaced, sent on WhatsApp, is all we need.

An equivalent part whose technical values (power, voltage, dimensions, connection type) match exactly will not damage the unit. When we propose an equivalent, we match these values and tell you about any difference in advance.

Simple problems such as a capacitor failure are fixed by replacing the part. For motors with burnt windings or worn bearings, replacing the motor is usually more economical and reliable.

We service Aldağ, Alarko Carrier, Üntes, Daikin, Aermec, Systemair, Trane, York, Mitsubishi Electric and all other Turkish and imported brands. On our brands page you can find brand-specific fault and spare parts information.

Yes. On units with an unreadable rating plate, or from manufacturers no longer in business, we find solutions by matching parts by dimensions and technical values.

A manufacturer's authorised service carries out work covered by the warranty. For units whose warranty has expired, an independent service provides maintenance, repair and parts replacement regardless of brand. For units still under warranty, we recommend checking the manufacturer's conditions first.

First we take details of the problem and the units by phone or WhatsApp. If needed, we come for a site survey or carry out a pre-diagnosis from photos/videos. Once you approve the written quotation, we schedule the work, then test and report when it is finished.

Yes, we issue an invoice for all work carried out. For corporate customers we also provide maintenance reports and work records.

Yes. We carry out maintenance and repair work for institutions such as public buildings, schools and hospitals, and provide documents that fit their tender and paperwork processes.

Yes. As YOİ Mühendislik we also service chillers, VRF systems, air handling units, heat pumps and precision air conditioning systems. For details, visit our main website.