Cold rooms and freezer rooms are heavily insulated, yet every time the door opens, cold escapes and warm, humid air gets in. In catering, food retail, pharmaceutical storage and logistics the door often opens dozens of times a day. An air curtain for a cold room forms an air barrier in this opening that reduces air exchange without obstructing staff, pallet trucks or forklifts.
In this guide we explain what physically happens when a cold room door is opened, why cold room air curtains work without heating, how a door contact controls operation and what to look out for when selecting and installing a unit. The technical details are taken from the data sheets and technical articles of the manufacturer Frico.
What happens when a cold room door is opened
Cold air is heavier than warm air. When the door of a cold room is opened, the cold air flows out at the bottom of the opening while warm air from the anteroom flows in at the top. This exchange starts immediately and continues as long as the door is open. The greater the temperature difference between the cold room and its surroundings, the stronger the flow. In a freezer room with clearly sub-zero temperatures the effect is correspondingly more pronounced than in a cold room for drinks.
Frico describes the consequences as follows: each time the door is opened, cold air escapes and at the same time warm, humid air enters from outside. This leads to energy losses, condensation and ice forming on floors and equipment. The refrigeration system then has to remove the heat and moisture that have entered.
Consequences: energy, icing and safety
Energy loss is only part of the problem. The moisture carried in with the warm air condenses on cold surfaces and freezes in freezer areas. Frico names several consequences that are noticeable in operation:
- Ice formation: in a freezer unit without automatic defrosting, a layer of ice gradually forms with every opening because the incoming moisture freezes again and again. Defrosting a large freezer room is laborious because goods often have to be moved for it.
- Risk of slipping: according to Frico, less ice on the floor means more safety because the risk of slipping falls.
- Visibility and labelling: with less condensation and ice, surfaces, packaging and shelf labels remain easier to read.
- Equipment: according to the manufacturer, less ice formation has a positive effect on the condition of the refrigeration system, lighting and fittings.
- Goods: according to Frico, a more even temperature helps the shelf life of food and medicines.
Humid air, condensation and ice are also familiar from home ventilation. We explain in detail how condensation forms on cold surfaces in our guide to condensation on windows. The same physical principles apply in a cold room, only at much lower temperatures.
Why cold room air curtains work without heating
At shop entrances in winter, air curtains are usually used with heating. At a cold room the aim is different: no heat should enter the room. Frico therefore explicitly recommends units without heating for cold room openings. The air curtain blows an even jet of air across the opening and so separates the two temperature zones.
On savings, Frico gives a specific manufacturer figure for the PAEC3200 series: according to it, the unit can reduce energy consumption by up to 85 % compared with an unprotected, open door. In general, referring to independent tests, the manufacturer states that correctly installed air curtains can reduce energy loss at an open door by up to 80 %. Both figures are maximum values under favourable conditions; the actual effect depends on door size, temperature difference, how long the door is open and installation.
Two Frico series in our range are explicitly intended for cold rooms. The following table summarises the manufacturer data:
| Feature | Frico PAECS | Frico PAEC |
|---|---|---|
| Application according to Frico | cold and freezer rooms, entrances to air-conditioned areas | cold rooms and entrance areas |
| Heating | none | none |
| Lengths | 1,050, 1,560 and 2,050 mm | PAEC 2500: 1,050, 1,560, 2,050 mm; PAEC 3200: 1,068, 1,578, 2,068 mm |
| Air volume | 1,450, 2,200 and 3,100 m³/h depending on length | steplessly adjustable |
| Mounting height | cold rooms up to 4 m, entrances recommended 2.5 m | in cold areas up to 5 m, depending on the area |
| Motor, voltage | EC, 230 V | EC, 230 V |
| Protection class | IP44 | PAEC 3200: IP44 |
The slim PAECS cold room air curtain is connected via a 1.5 m cable with plug and mounted horizontally with the supplied wall brackets. For ceiling mounting, Frico offers accessories such as ceiling brackets and threaded rods.
Door contact and controls: output only when the door is open
A cold room air curtain does not have to run at full output all the time. According to the data sheet, the air volume of the PAECS series can be set separately for an open and a closed door. A door contact reports the status to the unit: with the door closed the fan runs at low speed, with the door open at high speed. The low setting is adjusted on the internal potentiometer, the high setting on the external PAMP10 potentiometer.
In the data sheets for PAEC and PAECS, Frico specifies the AGB304 door contact switch as the door contact, a position limit switch rated at 4 A at 230 V with protection class IP44. According to the manufacturer, one PAMP10 can control up to eight units, or up to four units with a length of 2 m. Alternatively, the unit can be controlled via a 0 to 10 V signal from the building management system. The control cables of the PAECS are brought out for this purpose.
- Door closed: low speed or off, low power consumption and little noise
- Door open: high speed, stable air barrier across the whole opening
- Connection to the building management system: on and off and fan speed via 0 to 10 V
Air curtain or strip curtain?
Many cold rooms are fitted with PVC strip curtains. They are simple and inexpensive, but obstruct visibility and passage and become dirty over time. Frico names as advantages of the air curtain that the view into the cold room remains clear and that vehicles and goods can get in and out more easily. According to the manufacturer, the airflow remains intact regardless of how many vehicles pass through the opening.
Which solution fits in an individual case depends on the temperature difference, how often the door is opened, the traffic and the hygiene requirements. Discuss the choice with your refrigeration contractor, because the air curtain affects the load that the refrigeration system has to remove. If you are planning a new catering kitchen with a cold room, you will find further advice in our guide to planning a commercial kitchen.
Selection and installation in practice
The same basic rules apply to cold rooms as to any other entrance. Frico recommends that the air curtain covers the full width of the opening and is mounted as close to the opening as possible. For wide doors, several units are placed side by side. The actual mounting height is decisive for the selection. You will find detailed advice in our guide on sizing an air curtain correctly.
Also pay attention to the following points:
- Protection class: a higher protection class makes sense in damp areas. According to the manufacturer, PAECS and PAEC 3200 are rated IP44.
- Noise: for the PAECS, Frico states a sound pressure of 44 to 51 dB(A) at 50 % and 62 to 67 dB(A) at 100 % airflow depending on length, measured at a distance of 5 m. With a door contact the unit runs at the low setting most of the time.
- Maintenance: on the PAECS the front section can be removed for installation and maintenance, and the outlet grille is adjustable.
- Power supply: the PAECS is supplied with a plug. Door contact, potentiometer or BMS connection require professional wiring.
For installation and connection, we work with installation partners who can take care of fitting, installation and maintenance on site.
Frequently asked questions
Does a cold room air curtain need heating?
No. Frico recommends units without heating for cold room openings, because the aim is to stop warm air from entering. The PAEC and PAECS cold room series are offered without heating.
Is an air curtain also suitable for freezer rooms?
According to Frico, the PAECS is intended for cold and freezer rooms. In freezer rooms in particular, reducing the moisture carried in is important, because otherwise it freezes as ice on the floor, evaporator and fittings.
Does the air curtain also run when the door is closed?
That can be set. With a door contact, the PAECS runs at low speed when the door is closed and switches to the high setting when it opens. The two settings are adjusted separately.
How much energy does an air curtain save at a cold room?
For the PAEC3200, Frico states up to 85 % lower energy consumption compared with an unprotected, open door. That is a maximum value. How much you actually save depends on door size, temperature difference and how long the door is open.
Conclusion
Every time a cold room door opens, it costs cooling and brings moisture into the room, which causes problems as condensation or ice. An air curtain without heating separates the temperature zones without obstructing passage and, according to the manufacturer, reduces energy losses, ice formation and defrosting effort. What matters is a suitable length across the full door width, the right mounting height and a door contact that adapts the output to the door status. You will find Frico cold room air curtains and matching accessories in our air curtains category.
