Air Curtains &
Over Door Heaters

An overdoor heater (often referred to as an over door heater or simply a door heater) is a linear fan heater positioned above a door.  It produces a relatively low velocity air stream that blows down across the doorway.

Electrically heated overdoor heaters (such as those manufactured by BN Thermic) incorporate electric heating elements which heat the moving air to a pleasantly warm temperature.

Frequently used in shops, cafes and restaurants, overdoor heaters provide a warm welcome for customers and localised heating at a point of high heat loss.  Overdoor heaters also mitigate against cold draughts.

An air curtain is a linear device installed above a door.  Its primary function is to produce a stream of air across an open doorway creating an invisible barrier and, in doing so, limiting the loss of warm air.

Some air curtains offer no heating whatsoever and these are generally known as ambient air curtains.  However, an unheated, high velocity air stream induces a very noticeable cooling effect which can be uncomfortable for people in the vicinity.  For this reason, most air curtains are supplied with either built-in electric heating elements or hot water coils.

An overdoor heater (often referred to as an over door heater or simply a door heater) and an air curtain are similar in that they are both positioned above a door and produce a stream of air directed downwards towards the floor.

The difference is the velocity of the air stream.  Overdoor heaters produce a relatively low velocity air stream when compared to a similarly sized air curtain.  The implications of this difference are as follows.

• Comparing units with the same kW output, an overdoor heater will produce an air stream that feels warmer
• An overdoor heater will be quieter than a similarly sized air curtain
• An overdoor heater will not be as effective at producing an invisible barrier across an open doorway as an air curtain and, therefore, will not be as efficient in limiting the loss of warn air from a heated building

An overdoor heater (often referred to as an over door heater or simply a door heater) is most commonly used in high street shops, cafes, small-scale reception areas etc.  Because it is relatively quiet compared with a similarly sized air curtain, it is more welcome when people are positioned in close vicinity to the door.

An air curtain reduces heating bills by creating an invisible air barrier across a doorway and preventing heated air from escaping.  Higher velocity air curtains will produce a more effective barrier and be suitable for a higher mounting position but will produce more noise than a lower velocity equivalent.  Higher velocity air curtains will also need a higher output heater to achieve an acceptable air stream temperature resulting in somewhat higher running costs.

BN Thermic offers two types of air curtain.

High capacity air curtains are ideally suited to larger commercial and industrial premises such as superstores and large-scale reception areas.

Commercial air curtains are better suited to convenience stores, small-scale reception areas and lobbies etc.

There are many ways of controlling overdoor heaters and air curtains.  The most suitable approach will be determined by the physical layout of area and how the space is being used. Here is a quick overview of the control options. If you would like to discuss a specific project, please call our Customer Service Department.

Overdoor Heaters and Commercial Air Curtains

The simplest approach is to simply turn the overdoor heater or air curtain on and off using the built-in switch (overdoor heaters only) or suitable wall-mounted switch.

A wall-mounted controller can be positioned in a more convenient location and will provide a higher degree of control, offering on/off/high heat/low heat/ fan only settings.

Thermostatic control can be achieved by ordering a model with a built-in thermostat or by connecting a wall mounted thermostat to the heater.  To prevent unauthorised personnel adjusting the temperature setting, we generally suggest a tamperproof thermostat.

Thermostatic control is particularly important to prevent overheating in a confined area.  A good example is when the overdoor heater or air curtain is installed in the area between two sets of doors rather than in a large open space.

SystemX Control

Both overdoor heaters and commercial air curtains are available in SystemX format.  High capacity air curtains are only available in this format.  This technology is particularly useful when there is a need to control more than one overdoor heater or air curtain from a single point.  A SystemX controller can be linked to a chain of up to 12 overdoor heaters or air curtains with control connections made using data cable.  The SystemX approach ensures very quick and error free installation.

Depending on the controller selected, SystemX can offer manual control, thermostatic control, programmable thermostatic control or simple BMS (building management system) interface.