International Environmental

International Environmental is a manufacturer of hydronic fan coil units and terminal HVAC units for commercial and residential applications, operating under the brand name IEC. Headquartered in Oklahoma City, Oklahoma, International Environmental has built more than 75 years of expertise in fan coil unit engineering and manufacturing, establishing itself as the industry leader in hydronic fan coil systems for hospitality, multi-family, healthcare, and education facilities. IEC operates a state-of-the-art manufacturing facility in Oklahoma City that produces the full range of vertical, horizontal, and specialty fan coil configurations for North American commercial projects. The IEC product portfolio spans vertical stack units, horizontal ceiling units, direct-drive blower coils, belt-drive blower coils, and fan-powered terminal units, with specialty systems such as the SureFlow two-pipe platform delivering four-pipe system performance. For mechanical engineers and HVAC contractors specifying hydronic terminal equipment, IEC provides custom-engineered solutions across the broadest fan coil product range in the North American market.

Product Lines

Vertical Stack Fan Coil Units

IEC vertical stack fan coil units are designed for multi-story applications where units are stacked floor-to-floor, sharing a common hydronic riser and serving individual rooms in hotels, multi-family buildings, and similar residential-over-commercial construction. The vertical stack configuration minimizes the piping and wiring infrastructure required per floor by aligning units on a common riser, reducing both installation labor and mechanical room space. IEC vertical stack units are available in a range of cooling and heating capacities to match the load requirements of individual rooms in multi-story hospitality and residential projects. Mechanical engineers specifying IEC vertical stack units for hotel corridors or apartment buildings benefit from IEC's custom engineering capability to match unit dimensions and capacities to the structural and acoustic requirements of the project.

Horizontal Ceiling Fan Coil Units (CXB Series)

IEC horizontal ceiling fan coil units, designated as the CXB series, are compact designs adaptable for both exposed and concealed installation in smaller ceiling spaces in commercial and light-commercial applications. The CXB series is appropriate for perimeter zone applications in offices, retail spaces, and healthcare facilities where ceiling height and mechanical room access limit the use of larger AHU equipment. IEC CXB units are available in horizontal airflow configurations and can be ducted or applied as non-ducted units depending on the distribution requirements of the space. Contractors installing IEC CXB ceiling fan coils in retrofit applications can work with IEC's engineering team to specify units that match existing hydronic riser capacity and space constraints.

SureFlow Two-Pipe Fan Coil System

IEC SureFlow is a specialty fan coil platform designed to deliver four-pipe system performance, providing simultaneous heating and cooling capability, from a two-pipe hydronic installation. The SureFlow system achieves independent heating and cooling from a single pipe connection by integrating a hydronic heat exchanger and electric resistance element in the unit, reducing the piping infrastructure required compared to a conventional four-pipe design. SureFlow is designed for multi-family, hospitality, and healthcare projects where occupants require simultaneous heating and cooling in adjacent spaces but the cost or complexity of a full four-pipe distribution system is not feasible. IEC SureFlow is the appropriate specification when a project requires zone-level heating and cooling flexibility but two-pipe distribution infrastructure has already been installed or is specified for the project.

Direct Drive and Belt Drive Blower Coils

IEC direct-drive blower coils are horizontal or vertical units designed for larger-capacity applications where individual fan coil units are not sufficient for the zone load. Direct-drive blower coils use motors directly coupled to the fan wheel, providing quieter operation and lower maintenance compared to belt-drive configurations in the same capacity range. IEC belt-drive blower coils are horizontal or vertical units for large common area applications, including lobbies, atriums, and large open commercial spaces, where motor speed adjustment via belt-drive ratio allows system optimization for the specific airflow and pressure requirements of the space. Mechanical engineers specify IEC blower coils for high-capacity applications where individual room fan coil units are undersized and dedicated AHUs would overserve the zone.

Why Contractors Specify International Environmental

International Environmental has maintained more than 75 years of fan coil unit manufacturing expertise in Oklahoma City, establishing a production and engineering record that positions IEC as the industry leader in the commercial hydronic fan coil category. IEC's custom engineering capability allows the company to produce units engineered to project-specific dimensional, acoustic, and capacity requirements rather than fitting projects to standard catalog configurations. The SureFlow two-pipe platform addresses the four-pipe functionality requirement without the cost of a full four-pipe distribution system, a specification advantage for multi-family and hospitality projects with riser cost constraints. IEC's manufacturing facility in Oklahoma City produces the full product range, supporting lead-time and quality control for North American commercial projects.

How to Choose a International Environmental Product

The most important decision variable when specifying an IEC fan coil unit is the installation orientation and distribution type: whether the unit needs to be vertical-stack, horizontal ceiling, vertical floor, or cabinet-mounted, and whether ducted or non-ducted distribution matches the project's architectural and mechanical constraints.

For multi-story hospitality and multi-family projects with individual room temperature control, the IEC vertical stack fan coil unit is the standard specification, allowing stacking on a common hydronic riser with individual room controls. The key sizing variables for IEC vertical stack units are the room cooling load in tons or MBH, the hydronic supply water temperature for cooling and heating, and the unit height and width constraints set by the architectural chase dimensions.

For ceiling-mounted commercial applications, the IEC CXB horizontal ceiling fan coil is appropriate in smaller ceiling spaces where exposed or concealed installation is required. Airflow volume, static pressure capability, and duct connection size are the key specifications for CXB ceiling units.

For projects where four-pipe heating and cooling performance is required but only two-pipe distribution infrastructure is available, the IEC SureFlow system is the designed solution. Which IEC blower coil is right for large open spaces depends on the zone's design airflow in CFM, the available static pressure for duct distribution, and whether direct-drive or belt-drive motor configuration better matches the speed adjustment requirements of the application.

IEC recommends early engagement with their engineering team on custom projects to confirm dimensional tolerances, acoustic ratings, and capacity verification before submittal documentation is prepared.

FAQs

Where are International Environmental fan coil units manufactured?

International Environmental fan coil units are manufactured at IEC's state-of-the-art manufacturing facility in Oklahoma City, Oklahoma. IEC has maintained over 75 years of fan coil manufacturing expertise at this location, producing the full range of vertical, horizontal, and specialty fan coil units for North American commercial projects.

What warranty does International Environmental offer on fan coil units?

IEC warranty terms are available through authorized IEC representatives and on iec-okc.com. Contractors and mechanical engineers should request current warranty documentation for the specific IEC product line being specified, as terms may vary by unit type and application.

What is the difference between IEC vertical stack units and horizontal ceiling units?

The difference between IEC vertical stack units and horizontal ceiling units is installation orientation and application type. Vertical stack units are designed to be installed vertically in chases or closets in multi-story buildings, stacked floor to floor on a common hydronic riser, and are the standard configuration for hospitality and multi-family individual room applications. Horizontal ceiling units (CXB series) are installed horizontally in ceiling cavities for perimeter zone applications in commercial spaces where vertical installation is not practical.

What is the IEC SureFlow system and when is it specified?

The IEC SureFlow system is a fan coil platform that delivers four-pipe simultaneous heating and cooling performance from a two-pipe hydronic installation. SureFlow is specified on multi-family, hospitality, and healthcare projects where adjacent spaces require independent heating and cooling but a full four-pipe distribution system is not feasible due to cost or existing piping infrastructure constraints.

What applications are International Environmental blower coils designed for?

IEC direct-drive blower coils are designed for larger-capacity HVAC applications in lobbies, atriums, and large open commercial spaces where individual fan coil units are undersized for the zone load. Belt-drive blower coils are used in similar large-capacity applications where motor speed adjustment via belt-drive ratio allows optimization of airflow and pressure for the specific space requirements.

How are IEC fan coil units controlled?

IEC fan coil units are compatible with standard hydronic system controls including two-pipe and four-pipe thermostat configurations, and IEC offers accessories including thermostats, control boards, and Wi-Fi thermostats for use with IEC units. The specific control compatibility for an IEC fan coil unit depends on the unit model and the system configuration being specified, and IEC's engineering team can confirm control compatibility for custom applications.