Most Frequently Asked Questions About PTC Heating  What are PTC (positive temperature coefficient) heaters? PTC, positive temperature coefficient, is a term used to describe the resistance characteristics of ceramic thermistor heating elements and their relationship between temperature and current flow through the device.  You may also see the term positive temperature coefficient resistor (PTCR) used in scientific & manufacturing. The term means that as the temperature of the device increases, the resistance also increases, slowing the current flow and the ceramic element's temperature increase.  The device's temperature is on the X axis on the top graph, with the resistance of...

What is better?  UL Listed or CE Marked?

The two marks aren't comparable in that they are for different purposes.  UL is a private testing laboratory and CE marking to create conformity across diverse European countries and languages for the common European market.  UL began 80 years before CE for entirely different purposes. Learn More.

Industrial Electric Air Heaters

Electric duct heaters are used for industrial, commercial, and residential applications by being placed in the airflow of HVAC ductwork to transfer heat into factory floors, offices, and homes to warm the air.

PTC heating elements are used in duct air heating systems.

Ceramic PTC, positive temperature coefficient, heating elements will not cause the ignition of dust or other combustible materials in the ductwork since they do not use resistive wires.

Finned structure for air heaters

The structure for transferring heat to the air flowing through the ductwork needs to cause a minimum pressure difference across the elements.  While multiple types of fin structures are used the Delta fin provides the lowest pressure drop across the heater.

Duct heater temperatures

Depending on the application there are both high and low-temperature duct heaters available.  Industrial process heaters often require high heat for a manufacturing operation requiring material heating.  While space heating for offices or homes requires lower temperature heating elements.

What do duct air heaters look like?

Modern duct heaters are aluminum honeycomb or finned structures that fit either partially or completely across the inside of the square, rectangular, or round ductwork.

What typical features of PTC electric heaters?

PTC electric airflow heaters come in multiple sizes, voltages, and wattages.  The dimensions of the ductwork and available voltage are primary factors.  The output wattage and temperature requirements are taken into account.

What is differential pressure in the ductwork?

If you ever changed your home air conditioning or heating system filter it is because a dirty filter has a higher differential pressure than a clean one.  Differential pressure is the resistance to airflow through a filter, heater, or cleaner placed in the air stream.

Air heaters' primary purpose is to heat the air in a specific space or area. The space to be heated could be an industrial process, air duct to a larger area, equipment cab, or interior of a house or car.  The design of the duct or forced air heater is dependent on the specific application.

The design of this type of heater is a honeycomb or other fin-type structure that will transfer heat efficiently to the air being forced across the structure.  Electric resistance heaters are embedded inside the fins or honeycomb structure that in turn transfers the heat to the air flowing through.

For process air heaters the fin or honeycomb structure made of aluminum or stainless steel typically will span the inside dimensions of the duct carrying the air to an area targeted for heating.  This creates a very efficient & consistent heat transfer.

There is an extensive variety of heat exchangers arrangement for duct heaters including finned tubular, open coil, honeycomb, triangular, and straight fins.  The configuration depends on the required airflow and each offers different heat transfer characteristics.