Thermal space, a determining factor in the design of electric heating resistors (25/05/2023)

In the electric heating elements’ industry there are many key factors to take into account in order to implement electric heaters in the best way. One of the most important is the thermal space.


In any such design, whether for air or liquid heating, sizing the heating area is as important as sizing the junction box area. The electrical resistance of a heating element determines its ability to generate heat, and the amount of heat it generates will be influenced by the surrounding thermal space. The creation of this space is intended to protect all electrical and electronic components from high temperatures.

In some situations, the space available for the connection area is small, so the thermal space will be limited. If this thermal space is too small, the heating element can be overheated and its electrical resistance may change, affecting the amount of heat generated. The existence of this probability forces in these cases the placement of heat sinks inside the connection box by means of fans, grills or cooling elements.

On the other hand, if the thermal space is too large, the air can be cooled before leaving the device. This would reduce the effectiveness of the heating element when heating the room.

Taking all this into account, the measurements and the type of separator with which a thermal space is created around the heating elements must be chosen considering multiple variables: the medium to be heated, the flow rate, the type of regulation, the temperature working temperature, the sheath material... Actually, it is very important to take into account the difference between working temperature and sheath temperature.

The working temperature is the one with which a device or component normally works following its technical specifications. The sheath temperature refers to the one of the surface of an object, such as a cable or a tube covered by thermal insulation. The latter can be significantly higher than ambient temperature, something that can affect the durability and performance of electrical components.

The thermal space also affects the safety of electric heaters. If it is insufficient, it may cause a fire if the heating element gets in contact with nearby combustible materials.

At Electricfor we always design each industrial electric heater according to the particular needs of each client, with an adequate thermal space that guarantees not only its efficiency when it comes to heating in a uniform and effective manner, but also its safety and durability.

Thermal space, a determining factor in the design of electric heating resistors
Thermal space, a determining factor in the design of electric heating resistors