Section 1: Product Overview

The Horizontal Concealed Fan Coil Unit is the most widely deployed terminal device in commercial and residential central water-based air conditioning systems globally. Its defining characteristic — horizontal body orientation combined with fully concealed ceiling void installation — positions it as the terminal device of choice for any building project where interior design quality, space utilization efficiency, and acoustic comfort are priority design requirements.

When installed correctly within the ceiling void, the Horizontal Concealed fan coil unit is completely invisible from the occupied space. The room occupant interacts only with the supply air grille delivering conditioned air, the return air grille drawing room air back into the unit for reconditioning, and the wall-mounted thermostat providing temperature set point and mode control. The mechanical components — fan motor, heat exchanger coil, condensate tray, filters, and all water and electrical connections — are entirely within the ceiling structure. This level of architectural integration is unachievable with wall-mounted split units, floor-standing fan coils, or exposed ceiling units, and it is the reason that concealed fan coil systems are the standard specification for hotels, premium office buildings, high-end residential developments, healthcare facilities, and any application where the interior environment is a significant part of the building's value proposition.

Beyond aesthetics, the central water-based system architecture within which the Horizontal concealed fan coil unit operates provides fundamental Energy Efficiency advantages. Chilled and hot water are generated centrally by high-efficiency water-cooled chillers and boilers, distributed through insulated pipe networks, and delivered to each room's fan coil unit precisely when and in the quantity that room requires. This centralized generation and distributed delivery approach achieves coefficient of performance values that individual room refrigeration cycle systems cannot match, and it enables the building energy management system to optimize total system energy consumption in ways that are impossible with distributed standalone units.

Dezhou Pengkai Air Conditioning Equipment Co., Ltd. is a comprehensive HVAC manufacturer based in Dezhou, Shandong Province, integrating research and development, production, sales, installation, and after-sales service. We supply fan coil unit products to HVAC engineering contractors, building developers, mechanical and electrical consultants, and construction procurement teams across Southeast Asia and global markets.

Section 2: Product Structure and Key Components

Fan and Motor Assembly The fan assembly uses a centrifugal impeller — either forward-curved multi-blade or backward-curved aerofoil-section — driven by an alternating current induction motor as the standard configuration. Three-speed operation is achieved by switching between different motor winding configurations, providing low, medium, and high speed settings that correspond to approximately 60, 80, and 100 percent of rated airflow respectively. The low-speed setting is the most commonly used during steady-state room temperature maintenance, providing the lowest noise level and lowest energy consumption while maintaining adequate air circulation. High-speed operation is used for rapid temperature pull-down when the room is first entered or when occupancy load is at its peak.

For premium applications, direct current brushless motors — EC motors — are available as an upgrade option. EC motors provide stepless speed control across the full speed range from near-zero to rated speed, significantly lower energy consumption at part-load conditions compared to AC motor three-speed switching, and longer service life due to the absence of brush wear and the more controlled operating conditions of the electronic commutation system. EC motor configurations are increasingly specified for hotel and premium residential applications where energy efficiency certification requirements and guest comfort standards are most demanding.

Copper Tube and Aluminum Fin Heat Exchanger Coil The heat exchanger coil is the thermal performance core of the Horizontal Concealed Fan Coil Unit. It consists of seamless copper tubes in a staggered array connected to aluminum alloy fins with a hydrophilic surface coating. The copper tube and aluminum fin combination is the industry standard for HVAC heat exchangers, selected for the combination of copper's high thermal conductivity and corrosion resistance in water systems with aluminum's light weight, workability into the thin fin geometries required for high surface area density, and hydrophilic coating that promotes condensate drainage from fin surfaces during cooling operation.

The tube-to-fin contact thermal resistance — which directly determines how efficiently heat transfers from the water inside the tubes to the air flowing over the fin surfaces — is minimized by the mechanical tube expansion process used in manufacturing. After fins are assembled onto tubes, hydraulic expanding mandrels are driven through each tube, permanently expanding the tube diameter and pressing the tube wall into tight contact with the fin collar, eliminating the air gap that would otherwise exist at this critical thermal interface.

Condensate Tray and Drainage System The condensate tray is positioned below the heat exchanger coil to collect condensed moisture that forms on the fin surfaces during cooling operation when coil surface temperature is below the dew point of the room air. The tray is fabricated from galvanized steel with a continuous closed-cell foam insulation lining applied to its underside and exterior surfaces. This insulation serves two essential functions: it prevents the tray surface temperature from dropping low enough to cause external condensation on the tray exterior — which would result in water dripping onto the ceiling void structure or ceiling tiles — and it reduces heat gain into the chilled water system from the surrounding ceiling void environment.

The tray is designed with a 1 to 2 percent longitudinal slope toward the drain outlet, ensuring that condensate flows consistently toward the outlet connection without pooling at the low end of the tray. The drain outlet connects to a flexible condensate drain pipe that routes condensate to the building drainage system via a P-trap or S-trap that prevents sewer gas from entering the unit through the drain line.

Air Filter A washable air filter is installed at the return air inlet of the unit, positioned to intercept all return air before it reaches the heat exchanger coil. The filter is fabricated from woven nylon mesh, knitted metal wire, or non-woven fabric and captures airborne dust, lint, and particulate matter, preventing accumulation on the fin surfaces that would progressively reduce heat transfer efficiency and airflow capacity. The filter is designed for routine removal, cleaning under running water, and reinstallation without tools. Regular filter cleaning — typically every three to six months in normal office and residential environments — is the single most important maintenance action for maintaining the energy efficiency and air quality performance of the Ceiling Concealed Central AC Terminal.

Cabinet and Thermal Insulation The unit cabinet is fabricated from galvanized steel sheet, providing structural rigidity and corrosion resistance in the ceiling void installation environment. The internal surfaces of the cabinet are lined with flame-retardant closed-cell elastomeric foam insulation. This lining serves four functions simultaneously: it prevents external condensation on the cabinet surfaces during cooling operation; it reduces heat gain into the cooling water system from the surrounding environment; it attenuates airborne fan noise radiated through the cabinet walls; and it provides a degree of fire safety by using non-combustible or self-extinguishing insulation materials in the ceiling void where fire risk management is a building safety design consideration.

Electrical and Control Components The unit electrical system includes the motor terminal block for three-speed selection, the connection interface for the electric water control valve, and the wiring connections for the room thermostat. The electric water valve — either two-port or three-port depending on the hydronic system design — modulates or on-off controls the chilled or hot water flow through the heat exchanger coil in response to the thermostat's temperature control signal, providing the room temperature regulation function that is the fundamental purpose of the complete system.

Section 3: Technical Specifications

Complete Model Performance Data:

All models: maximum working pressure 1.6 MPa, water connection 3/4" BSP female, condensate connection 3/4" BSP male, unit height 250mm, unit depth 455mm.

Section 4: Static Pressure Selection Guide — Low Static Pressure vs High Static Pressure

Static pressure specification is one of the most important selection decisions for the Horizontal Concealed Fan Coil Unit and is frequently misunderstood by procurement teams working outside their core technical specialty. Selecting the wrong static pressure specification results in either insufficient airflow in high-resistance duct systems or unnecessarily high noise in low-resistance systems.

Low Static Pressure Configuration — ≤12 Pa Available External Static Pressure The low static pressure configuration is appropriate when the fan coil unit discharges air directly through a supply air grille with minimal or no duct run between the unit outlet and the room space. This configuration is common in hotel guestrooms where the unit is installed directly above the ceiling void of the room it serves, with short flexible duct connections to one or two supply grilles in the ceiling of the same room. The low static pressure configuration achieves the lowest noise levels in the range — 37 to 54 dB(A) across the model range — making it the preferred specification for noise-sensitive applications including hotel guestrooms, bedrooms, healthcare patient rooms, and library reading rooms.

High Static Pressure Configuration — 30 to 50 Pa Available External Static Pressure The high static pressure configuration is required when the supply air must travel through a rigid duct distribution system to reach multiple supply grilles, or when the duct run from the unit to the supply grilles is long enough to generate meaningful pressure loss. Open-plan office floors where a single fan coil unit serves multiple workstations through a branched duct network, hotel suites where the same unit serves the bedroom and bathroom through separate grilles, and commercial spaces where air must be distributed to multiple areas from a centrally located unit are the primary applications for the high static pressure configuration. The increased fan speed and power consumption required to deliver the higher static pressure result in modestly higher noise levels, which are typically acceptable in the commercial and office building applications where this configuration is most commonly used.

Section 5: How It Works — Air Conditioning Cycle

Room Air Intake Room air is drawn through the return air grille by the negative pressure created at the fan inlet. The return air grille may be integral with the unit face panel or may be a separate ceiling-mounted grille connected to the unit return air inlet by a short flexible duct. All return air passes through the washable filter immediately inside the return air inlet, where airborne particulates are captured before the air reaches the heat exchanger coil.

Heat Exchange — Cooling Mode In cooling mode, chilled water at approximately 7°C flows from the central chilled water plant through the supply water pipe to the heat exchanger coil, and returns to the chiller plant at approximately 12°C after absorbing heat from the room air. Room air passing over the fin surfaces of the coil transfers heat to the much cooler water inside the tubes. The air temperature drops from room temperature — typically 26-28°C in a cooling application — to the supply air temperature of approximately 16-18°C at the coil outlet. Simultaneously, the coil surface temperature drops below the dew point of the room air, causing water vapor in the air to condense on the fin surfaces and drain into the condensate tray. The cooler, drier supply air is delivered back to the room, reducing both the temperature and humidity of the occupied space.

Heat Exchange — Heating Mode In heating mode, hot water at approximately 50-60°C from the central boiler plant flows through the heat exchanger coil. Room air passing over the fin surfaces picks up heat from the hot water and is delivered to the room at supply temperatures typically in the range of 35-45°C, raising the room temperature to the thermostat set point. No condensation occurs in heating mode — the coil surface is above ambient dew point at all times.

Temperature Control The room thermostat continuously compares the measured room temperature with the user-set temperature set point. When room temperature deviates from the set point beyond the control dead band, the thermostat signals the electric water valve to open, allowing chilled or hot water flow through the coil, and starts the fan at the selected speed. When room temperature returns to the set point, the thermostat closes the water valve and stops the fan, conserving energy and maintaining thermal comfort without overshooting the target temperature.

Section 6: Manufacturing Process and Quality Control

Dezhou Pengkai Air Conditioning Equipment Co., Ltd. applies systematic quality management throughout Horizontal Concealed Fan Coil Unit production:

Copper Tube and Fin Coil Fabrication Copper tubes are cut to length and inserted through pre-formed fin arrays in the specified tube pitch and row depth configuration for each model. The tube expansion process uses hydraulic mandrels driven sequentially through each tube, permanently expanding tube diameter by a controlled amount to achieve the specified tight mechanical contact at the tube-to-fin collar interface. Each completed coil undergoes pressure testing at 1.5 times the maximum working pressure with dry air or nitrogen to verify zero leakage before assembly.

Impeller Dynamic Balancing centrifugal fan impellers are dynamically balanced after assembly to minimize vibration transmission to the unit cabinet and through the ceiling void structure. Residual imbalance directly affects acoustic performance — a misbalanced impeller generates a characteristic tonal noise at rotational frequency that is highly perceptible in quiet room environments. Dynamic balancing to the required grade is verified for every impeller before installation in the fan assembly.

Cabinet and Condensate Tray Assembly Cabinet panels are cut and formed from galvanized steel sheet and assembled with the insulation lining applied continuously to all internal surfaces. Condensate tray slope angle is verified against specification during assembly. Drain outlet connection dimensions and sealing integrity are tested before the tray is installed in the cabinet.

Electrical Assembly and Function Test Motor terminal block wiring, thermostat interface connections, and water valve interface connections are installed and verified for correct function at all three speed settings before the unit is sealed. Insulation resistance of the motor is measured and verified against rated values.

Final Inspection and Running Test Every completed Two Pipe Four Pipe Fan Coil Unit undergoes a running test at all three speed settings, verifying correct airflow at each speed, absence of abnormal noise or vibration, and correct condensate tray drainage with a measured water volume test.

Section 7: Product Features and Advantages

Complete Concealment for Premium Interior Environments The flat horizontal profile — 250mm body height across all models — allows complete installation within standard ceiling void depths. The only visible elements are the supply and return air grilles, which can be selected to match any ceiling finish material and grid pattern. This total concealment is the defining advantage of the Horizontal Concealed Fan Coil Unit over all visible terminal device alternatives.

Low Noise Operation — 37 to 54 dB(A) The combination of centrifugal fan aerodynamic design, dynamic-balanced impeller, and acoustic insulation lining produces noise levels from 37 dB(A) for the smallest model at low speed — equivalent to a quiet library environment — to 54 dB(A) for the largest model at high speed. This noise performance is appropriate for hotel guestrooms, bedrooms, offices, healthcare patient areas, and all other noise-sensitive occupied spaces.

High Energy Efficiency — EER 2.8 to 3.1 Seamless copper tube and hydrophilic aluminum fin coil construction with hydraulic tube expansion contact produces heat exchanger effectiveness consistent with EER values of 2.8 to 3.1, significantly above the minimum standards for commercial fan coil equipment. Combined with the inherent efficiency advantages of centralized water-based cooling generation, this delivers materially lower operating energy costs compared to distributed refrigerant-cycle systems.

Two-Pipe and Four-Pipe System Compatibility The Ceiling Concealed Central AC Terminal is compatible with both two-pipe seasonal switching systems — where the same piping carries chilled water in summer and hot water in winter — and four-pipe simultaneous cooling and heating systems where separate chilled water and hot water circuits allow different zones of the building to cool and heat simultaneously. This compatibility ensures the unit can be specified for the full range of building hydronic system designs without modification.

Left-Hand and Right-Hand Water Connection Options Water supply and return connections can be configured on either the left-hand or right-hand end of the unit body, allowing the most convenient connection routing to the building pipe distribution system without requiring offset pipe fittings in the ceiling void. This flexibility simplifies site coordination between the fan coil installation and the piping installation subcontractor.

Washable Filter for Low Maintenance Cost The standard washable mesh filter can be removed, cleaned under running water, dried, and reinstalled by building maintenance staff without specialist tools or knowledge. No consumable filter replacements are required under normal maintenance schedules, reducing the ongoing maintenance cost compared to disposable filter systems.

Section 8: Application Scenarios

Hotel Guestrooms and Suites Hotel guestrooms represent the highest-volume application for the Horizontal Concealed Fan Coil Unit globally. The completely concealed installation preserves the designed guestroom interior without any visible mechanical equipment, the low-speed noise level of 37 to 43 dB(A) for smaller models meets the strict acoustic requirements of hotel guestroom design standards, and the individual zone temperature control from the in-room thermostat allows each guest to set their preferred room temperature independently. The low static pressure configuration is typically specified for standard guestrooms; the high static pressure configuration serves suites and interconnected room configurations where a single unit serves multiple spaces.

Office Buildings and Commercial Premises Individual offices, small conference rooms, reception areas, and private meeting rooms in office buildings and commercial premises represent the standard application domain for the Ceiling Concealed Central AC Terminal. The high static pressure configuration serves open-plan areas where duct distribution from the ceiling void is required to reach multiple workstation positions or multiple room positions from a single unit. The concealed installation maintains the clean ceiling appearance specified in commercial interior fit-out standards.

High-End Residential Buildings Premium residential developments including villa projects, large-format apartments, and serviced apartment buildings specify concealed fan coil systems as the standard air conditioning terminal for the interior design quality and zone control flexibility they provide. The Horizontal Concealed Fan Coil Unit is installed in each bedroom and living area, with individual thermostats in each room allowing family members to maintain different temperatures in their private spaces while the central system optimizes overall energy consumption.

Healthcare Facilities Hospital wards, general consultation rooms, examination suites, pharmacy areas, and nursing station environments require air conditioning equipment that meets clinical hygiene standards and operates at noise levels compatible with patient rest and clinical concentration. The Two Pipe four pipe fan coil unit with washable filter, concealed installation, and low-speed noise performance of 37 to 45 dB(A) for smaller models meets these requirements in non-critical clinical areas. Note that operating theatres, ICUs, and clean room clinical areas require dedicated air handling and filtration systems beyond standard fan coil equipment.

Educational and Cultural Facilities Libraries, reading rooms, archive rooms, museum exhibition galleries, and school administration offices require air conditioning that operates with minimal acoustic intrusion into the quiet environment that these spaces require. The low-speed noise performance of the Horizontal Concealed Fan Coil Unit in smaller models is appropriate for these applications, and the concealed installation avoids any visual intrusion into the carefully designed interior environments of premium cultural and educational facilities.

Precision Manufacturing and Laboratory Environments Electronic component assembly areas, precision instrument production environments, research laboratories, and quality control rooms require stable temperature control without the air turbulence and acoustic intrusion of high-velocity supply air systems. The fan coil system's gentle centrifugal air delivery and individual zone temperature control capability serve these applications while the concealed installation keeps the clean-room aesthetic of precision production environments intact.

Section 9: Customer Application Feedback

Our horizontal concealed fan coil unit products have been supplied to hospitality, commercial, and residential projects across Southeast Asia and international markets:

"We specified Pengkai horizontal concealed Fan Coil Units for a 280-room hotel project. The low-speed noise performance met our acoustic design requirement for guestrooms, the left/right water connection flexibility simplified coordination with our piping contractor on site, and all units passed commissioning inspection without issues. The certification documentation package provided for the project submission was complete." — MEP Contractor, Hotel Development Project, Southeast Asia

"For a premium residential tower project, we installed Pengkai Horizontal Concealed Fan Coil Unit products in all apartments. The 250mm body height fitted comfortably within our ceiling void specification, and the EC motor option we selected for the master bedroom units has delivered the quiet operation our clients expected. After-sales support for replacement filter supply has been straightforward." — Building Services Consultant, Residential Development

"We have standardized on Pengkai fan coil products for our office building portfolio projects. The consistent quality across supply batches, the complete technical documentation including dimensional drawings for our ceiling void coordination, and the responsive after-sales team have made this our preferred specification for the Ceiling Concealed Central AC Terminal category." — HVAC Engineering Contractor

Section 10: Installation Guidelines

Pre-Installation Checks Verify that the selected model, static pressure configuration, water connection hand, and dimensional specifications match the project mechanical and electrical design documents. Confirm that the ceiling void depth at the installation position is sufficient for the unit body height of 250mm plus any required clearance above the unit for service access. Inspect the unit body, coil, fan assembly, and condensate tray for transport damage before beginning installation.

Suspension and Leveling The unit is suspended from the building structure above the ceiling void using threaded hanger rods at the four designated hanger bracket positions on the unit body. Anti-vibration rubber mounts are installed between the hanger rod brackets and the unit suspension points to attenuate vibration transmission from the fan assembly through the hanger rods to the building structure. The unit must be leveled transversely to ensure the condensate tray drains consistently toward the drain outlet — a unit that is tilted in the wrong direction will cause condensate to pool at the sealed end of the tray rather than draining, resulting in overflow and water damage to the ceiling below.

Water Piping Connection Connect the chilled/hot water supply pipe to the coil inlet connection and the return pipe to the coil outlet connection using flexible hose connections at the unit end to accommodate any minor positional offset and to prevent pipe vibration from transmitting directly into the unit body. Fit isolation valves, balancing valves, and drain cocks at the unit water connection points per the hydronic system design. Purge all air from the coil water circuit before commissioning.

Condensate Drainage Connect the condensate drain outlet to the building drain system using the specified drain pipe diameter and material with a P-trap immediately downstream of the unit drain connection. The P-trap water seal prevents sewer gas from entering the unit through the drain line. Ensure that the drain pipe has adequate fall to the nearest drain point — a minimum gradient of 1:50 is generally recommended. Test the drain system by introducing a measured volume of water to the condensate tray and verifying that it drains completely without overflow.

Electrical Connection Electrical connection must be performed by a qualified electrician. Connect the three-speed motor supply, thermostat interface wiring, and electric water valve wiring per the unit wiring diagram. Verify that the power supply voltage is within the rated range for the motor. Test all three speed settings from the thermostat after electrical connection.

Section 11: Maintenance Schedule

Monthly Inspection Inspect the return air grille and supply air grille for dust accumulation. Check the condensate drain for correct flow by observing tray drainage during cooling operation. Listen for changes in operating noise that may indicate developing bearing wear or impeller fouling.

Quarterly Filter Cleaning Remove the return air filter, wash under clean running water, allow to dry completely, and reinstall. For high-dust environments including commercial kitchens, workshops, and high-occupancy commercial spaces, increase filter cleaning frequency to monthly.

Annual Professional Inspection Clean heat exchanger fin surfaces using appropriate fin cleaning solution applied by spray and rinsed according to product instructions. Test electric water valve for correct open and close function. Check all water connection fittings for drips or seepage. Verify condensate tray slope and drain function. Test thermostat calibration accuracy. Inspect unit suspension and anti-vibration mount condition.

Section 12: Packaging, Shipping, and Lead Time

Packaging Each Horizontal Concealed Fan Coil Unit is individually packaged in protective carton packaging with foam corner cushioning and internal cardboard supports protecting the coil fins and fan assembly from transport damage. Water connection fittings, hanger brackets, and installation accessories are packed with the unit. Larger project orders are palletized for container loading. Export-grade outer packaging is available for sea freight shipments.

Minimum Order Quantity We accept both small-quantity orders for project sampling and large-volume orders for full building supply contracts. Please contact our sales team to discuss project-specific requirements, model mix, and volume pricing.

Lead Time Standard models in common configurations are available from warehouse stock for short lead times. EC motor configurations and high static pressure variants are produced to order with lead times confirmed at order placement.

Shipping We ship from Dezhou, Shandong Province. Sea freight, air freight, and international express courier options are all available. We work with established freight forwarding partners serving Southeast Asia, the Middle East, and global destinations. Both FCL and LCL sea freight options are available for project-volume orders.

Sample Policy Product samples are available for pre-order quality and specification verification. Sample costs and shipping fees are agreed with buyers prior to dispatch. We recommend buyers inspect samples before placing full project supply orders.

Payment Terms We support T/T bank transfer and other payment arrangements as mutually agreed. Please contact our sales team to discuss terms appropriate to your procurement process and order volume.

Section 13: Certifications and Quality Assurance

Dezhou Pengkai Air Conditioning Equipment Co., Ltd. manufactures horizontal concealed fan coil unit products in compliance with applicable national standards for fan coil unit performance, safety, and energy efficiency. Each production batch is subject to coil pressure testing, impeller dynamic balance verification, and completed unit running tests before dispatch. Product quality documentation is available to buyers upon request. We welcome third-party pre-shipment inspection arrangements for project-specific orders.