Description
Electric Rectangular Duct Heaters & Preheaters – EHR Series
Reliable Electric Heating for Ventilation and Air Handling Systems
The EHR Series Electric Rectangular Duct Heaters and Preheaters are designed for efficient heating and preheating of clean air in ventilation systems and air handling units (AHUs).
With a wide range of electrical power, duct dimensions, control options and monitoring functions, the EHR series can be configured to meet different HVAC and industrial air-heating requirements.
The heaters are manufactured with an aluzinc-coated metal enclosure and stainless steel heating elements, providing a practical and durable solution for installation directly into rectangular ventilation ductwork.
Applications
EHR rectangular duct heaters can be used in a wide range of ventilation and air-handling applications, including:
HVAC Ventilation Systems
The heaters can be installed in supply-air ventilation systems to increase air temperature before the air enters occupied areas or other sections of the ventilation system.
Air Handling Units
The EHR series can be used as a heating or preheating stage within air handling units (AHUs). Preheating can help maintain the required supply-air temperature under low ambient conditions.
Fresh Air Systems
Electric duct heaters provide controlled heating for fresh-air systems where incoming outdoor air needs to be heated before distribution.
Industrial Ventilation
The rectangular duct configuration makes the EHR series suitable for industrial ventilation systems where larger air volumes and customized duct dimensions are required.
Heating and Preheating Functions
The EHR series can be configured either as an air heater or air preheater.
For standard heater configurations, the temperature setpoint range is 0 to +30°C. Other temperature ranges can be configured according to project requirements.
For preheating applications, standard temperature ranges include -10 to +20°C and -30 to 0°C. Preheater configurations are additionally insulated.
This flexibility allows the same product family to be adapted to different HVAC operating conditions.
Technical Specifications
| Parameter | EHR Series |
|---|---|
| Product type | Electric rectangular duct heater / preheater |
| Application | Ventilation systems and AHUs |
| Heating medium | Clean air |
| Supply voltage | 1~230 V / 2~400 V / 3~400 V |
| Output power | 0.5–99 kW |
| Duct dimensions | Approx. 200 × 200 to 1000 × 1000 mm |
| Protection rating | IP44 |
| Heating elements | Stainless steel |
| Casing | Aluzinc-coated metal sheet |
| Temperature control | Optional electronic controller |
| Airflow monitoring | Optional |
| Pressure monitoring | Optional |
| Communication | RS-485 MODBUS available on EHR../MB |
| Contactor | Optional |
| Configuration | Standard or customized |
The published technical data specify 1~230 V, 2~400 V and 3~400 V supply options, 500 W–99,000 W output power, 200–1000 mm rectangular duct dimensions and IP44 protection.
Electronic Control Options
Depending on the selected configuration, the EHR series can be supplied with different control functions.
SI – Internal Temperature Setpoint
The SI configuration uses an internal temperature setpoint and a duct temperature sensor for controlling the heater.
SE – External Temperature Setpoint
The SE configuration allows the temperature setpoint to be adjusted externally using a separate control device.
CE – 0–10 VDC Control
The CE configuration allows the heater to receive an external 0–10 VDC control signal from another control system.
F – Airflow Control
The F configuration provides airflow monitoring to help prevent heater operation when adequate airflow is not available.
FC – Airflow and Pressure Control
The FC configuration combines airflow and pressure monitoring for additional protection and system control.
SR – Pressure Control
The SR configuration provides pressure monitoring. Available pressure monitoring ranges include 0–200 Pa and 0–500 Pa, depending on the selected configuration.
Airflow and Overtemperature Protection
Airflow monitoring is an important safety function for electric duct heaters.
The control system can monitor airflow and prevent the heating elements from operating when sufficient airflow is not detected. This helps reduce the risk of overheating when the ventilation fan is stopped or airflow is insufficient.
The Valtronika documentation also specifies two overtemperature thermostats: an automatic-reset thermostat at approximately 70°C for output-air temperature control and a manual-reset thermostat at approximately 100°C for overheating cut-off protection.
For standard applications, the published catalogue specifies a minimum air velocity of approximately 1.5 m/s through the heater.
RS-485 MODBUS and BMS Integration
For projects requiring building automation, the EHR../MB version provides an RS-485 MODBUS interface.
This allows the electric duct heater to be integrated into a Building Management System (BMS) and provides a convenient solution for centralized monitoring and control of ventilation heating equipment.
Construction
The EHR heater enclosure is manufactured from aluzinc-coated sheet metal. The heating elements use stainless steel tubes, while sealing components can be used to provide a tight connection with the ventilation duct system.
This construction is suitable for installation in rectangular HVAC ductwork where reliable electrical heating and straightforward mechanical integration are required.
Typical Model Configuration
The EHR model designation can be used to identify the main product configuration.
For example:
EHR 200x200x200/3.0/2/SE/FC/MB/K
This configuration indicates:
- EHR – electric rectangular duct heater
- 200x200x200 – duct width × height × heater length
- 3.0 – 3.0 kW heating capacity
- 2 – number of phases
- SE – external temperature setpoint
- FC – airflow and pressure control
- MB – RS-485 MODBUS
- K – contactor
The manufacturer documentation uses this type of model structure to identify the duct dimensions, heating capacity, phase configuration, controller and additional functions.
Why Choose an Electric Rectangular Duct Heater?
An electric duct heater is a practical solution when a ventilation system requires controlled air heating without using hot water, steam or a separate thermal-fluid circuit.
The EHR series provides several configuration options so the heater can be selected according to:
- Airflow
- Required air temperature
- Heating capacity
- Duct dimensions
- Electrical supply
- Control method
- Airflow requirements
- Pressure monitoring requirements
- BMS integration
- Installation requirements
This makes the EHR series suitable for both standard HVAC applications and customized engineering projects.
Applications
Typical applications include:
- HVAC ventilation systems
- Fresh-air handling units
- Air handling units (AHU)
- Supply-air heating
- Fresh-air preheating
- Industrial ventilation
- Commercial buildings
- Industrial buildings
- Warehouses
- Clean-air ventilation systems
- Heating sections in air-handling equipment
Engineering Selection
Correct sizing of an electric rectangular duct heater should consider several parameters:
Required heating capacity
The required heating power depends primarily on airflow and the required temperature increase.
Airflow
The airflow rate must be considered together with the heater’s allowable air velocity and pressure drop.
Electrical supply
Available electrical voltage and phase configuration must be confirmed before selecting the heater.
Duct dimensions
The heater should match the rectangular duct cross-section or be designed with suitable transition sections.
Control method
The required control method should be selected according to the HVAC control architecture, such as local temperature control, 0–10 VDC control, airflow/pressure monitoring or MODBUS/BMS integration.
Safety
Airflow monitoring and overtemperature protection should be considered when designing the complete ventilation heating system.
Custom Engineering
EHR rectangular duct heaters can be supplied with different combinations of controllers, monitoring systems and contactors. Customized configurations are also available according to project requirements.
For engineering projects, Wili can assist with heater selection based on:
- Airflow
- Inlet air temperature
- Required outlet temperature
- Duct size
- Heating capacity
- Voltage
- Number of phases
- Control signal
- BMS/MODBUS requirements
- Airflow and pressure monitoring
Technical Support and Selection
To select the correct electric rectangular duct heater, please provide the following information:
- Airflow – m³/h
- Inlet air temperature – °C
- Required outlet air temperature – °C
- Duct width × height – mm
- Available power supply – V / phase
- Required heating capacity – kW, if known
- Control method
- BMS/MODBUS requirement
- Airflow or pressure monitoring requirement
Our engineering team can then recommend a suitable EHR configuration for the ventilation or air-handling system.
Wili – Heating Solutions for Industrial and HVAC Applications
