Euro Controls

Choosing the right air curtain

Most electricians will install an air curtain at some stage but few probably do so on a regular basis. Phil Alcock, managing director at air curtain specialist Frico, looks at different types of curtain and issues affecting their installation.

Air curtains are most commonly found in retail premises but additionally in offices, hotels,
factories, warehouses: in fact, anywhere there is a need to protect doors that are regularly open and to provide comfort inside an entrance. Air curtains are also commonly used 'in reverse': in cold stores to keep cold air inside and in air-conditioned buildings in summer to prevent loss of the conditioned air.

Equipment referred to as an 'air curtain' falls into two distinct categories: true air curtains and
door heaters. The latter, frequently seen in retail premises, are inexpensive, simple to install and provide localised heating, but do not provide an air barrier. Although economical to fit, they do not have long life expectancy and can be inefficient, as most of the heat is sucked outside due to the low fan power.

True air curtains, the subject of this article, provide benefits of comfort, economy and long
operational life.

Air curtains come in a variety of types to suit different environments. Standard models, such
as the Frico AD series, are reliable, high performance units for most locations. More powerful industrial units are available and, increasingly popular, architectural air curtains finished in stainless steel are specified for prestigious buildings.

Heat sources may be electric, water or unheated (for cool rooms). The most common units are electric or water-heated, mounted above the door, while vertical units mounted to the side of the door are also gaining popularity.

The most important considerations when choosing air curtains are that the fan power is sufficient for the height of the door (manufacturers' information will assist with this) and that the curtain covers the full width of the open space.

Electrical requirements

Electric-heated units are convenient and provide relatively higher temperatures than water-heated units. That said, there is still a large market for water-heated units, the electrical connection of which is a simple single-phase circuit and control wiring.

Electric-heated 'true' air curtains almost always require a 3-phase supply. The high airflow
required to provide an adequate air barrier also requires a significant amount of heat to condition the air passing through the unit. Typically these units output up to 18kW or more of heating on a 3-phase supply. The fan itself is almost always single phase from a separate supply.

So, it is important to make an initial check of the power available and existing wiring, as it may well be necessary to upgrade both to allow installation of the correct air curtain.

Mechanical installation

Fitting air curtains is relatively simple but, as they are heavy appliances and often mounted at high level, a lift may be required. By definition, an air curtain is going to be in a building entrance, so access must also be considered.

Most over-door units have an option of wall or ceiling hanging, via brackets or threaded rods. Even the most difficult locations can normally be accommodated in this way. A popular and simple solution is to recess the air curtain in a ceiling void. An air curtain package designed for recess mounting will ensure that correct clearances are maintained and provide a more reliable installation.

Controls

The simplest controls are output and fan speed switches. Controls are mounted remotely for
convenience and normally require a multi-core connection of around 10amp capacity. They
can be enhanced with the addition of thermostats for economy, door or occupancy activation
and BMS systems. All control options are relatively easy to connect but there are a few things to consider. Many of the more powerful electric air curtains have a fan overrun to cool the elements; this means that the single-phase supply should remain available even when the heating circuit (3 phase) is off. Units should also be correctly isolated for maintenance.

Commissioning

Air curtains require no specific commissioning other than to check that the fans, heating and
controls are operating.

Maintenance

Regular maintenance is limited to cleaning the inlets and ensuring no restrictions to airflow from dust and dirt build up. In locations such as clothes shops, hairdressers and restaurants, cleaning may be required frequently. In other situations, an annual check may be sufficient. If a problem does occur, it will most likely trip the thermal cut-outs, which will require an electrician to reset.

Electricians faced with an air curtain installation should not be daunted; it is relatively
straightforward, as long as the above considerations are taken into account. Manufacturers'
installation manuals will provide detailed guidance and, at Euro Controls UK Ltd, we are happy to provide technical advice pre, during and post installation.

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Submitted by Tim Watts on Thursday 15th September 2011