Top tips for air curtain installation

Air curtains can help retail, commercial and industrial customers to save energy by reducing the amount of cold air that enters their building, while keeping the warm air inside.  To maximise the savings possible, air curtains need to be designed, sized, installed and controlled correctly.  Here Martin Phillips, marketing manager at Thermoscreens shares his technical tips for efficient air curtain installations.
 
1. Take the time to get it right
A poorly designed, selected or installed air curtain can actually consume more energy than if no air curtain was installed at all.  Take your time to get the spec right and you will ensure optimum performance and happy customers.
 
2. Air curtain vs space heater 
An air curtain isn’t designed to heat a room – it is designed to disrupt natural convection and reduce heat loss around frequently used entrances and doorways.  Although its air stream is warm (unless it’s an ambient/no heat model) and contributes to the heating around an entrance, air curtains actually work alongside a building’s heating system, rather than replace it.  Don’t confuse air curtains with over door heaters. Over door heaters are not designed to form a climate separation but merely to offer some local heating around the door way
 
3. Sizing up
When choosing which air curtain would be right for an application, it’s important to note that they should be specified on the size of the door, not the kW output.  Air curtains are generally available in 1m, 1.5m and 2m lengths and can be seamlessly joined together if needed.  
 
4. Perfectly positioned
Air curtains should be fitted horizontally over a door, or, if necessary, mounted vertically to the side.  They can be surface mounted or recessed, but must be installed inside the doorway, with the discharge airstream as close to the opening as possible.  They should be just wider than the opening with an overlap at both sides (or at the top if it is a vertical installation). 
 
5. Air stream success
It is really important to spend time getting the discharge air stream right; an air curtain won’t be effective if it has too little velocity or is too powerful.  The discharge air stream should be able to discharge air down to floor level  and across the entire width of the opening at a suitable air temperature and speed (2m/s at 30cm above the floor level is a good guide).  Don’t forget to factor in the characteristics of the building (height, orientation etc.) and the outdoor climate conditions (humidity, prevailing winds etc.) as well as the power requirements. 
 
6. Still not sure? Ask for advice
If you aren’t sure about how to set up an air curtain, there’s plenty of advice out there.  An engineering design procedure for calculating the supply air flow and thermal capacity of an air curtain is explained in the BSRIA Application Guide 2/97, Air Curtains – Commercial Applications.  Manufacturers should also be able to provide assistance.

7. Use an efficient heat source 
An air curtain’s warm air can come from various sources, including direct electric heating and low, medium or high temperature hot water.  Modern air curtains are designed to operate with 60/40 condensing boilers and heat pumps to increase their overall efficiency and deliver even greater savings to the customer.  The more efficient the heat source, the more efficient the air curtain.
 
8. In control
Many air curtains use manual controls which allow the user to change the settings for the flow and temperature of the air stream.  In our experience, these controls are very rarely adjusted by a customer so the settings will only be right some of the time, and wrong a lot of the time. To stop this waste of energy and money, automatic controls are now widely available which allow the air curtains to operate at an optimum setting all of the time.
 
9. Whatever the weather
Weather compensation controls can further improve efficiency for a user.  These state of the art controls monitor the outdoor climate via a sensor and automatically adjust the air stream discharge temperature accordingly.  So a warmer temperature will be selected if it is cold outside, and vice versa. 
 
Along with the other members of the HEVAC air curtain industry group, Thermoscreens is committed to helping architects, consultants and installers to select the right products and fit them correctly. 
Developed in conjunction with FETA, our online Air curtain checklist is free to use and gives guidance on best practice.