Biddle CA2 Manual do Utilizador descarregar pdf (Página 10)

The correct selection

An air curtain functions well if it covers the entire doorway and has sufficient heat

capacity to bring the incoming cold air to a comfortable temperature. The selection

of the right type of air curtain depends on door height and door width and of the

volume of natural ventilation through the open door.

1. Door height (from floor to bottom of unit) and door width

Based on these known data an air curtain can easily be selected from the table on

this page. It is important for the distance between the air curtain and the door to be

as small as possible. In addition, the air curtain should be at least as wide as the

doorway.

2. Natural ventilation

It is difficult to determine the volume and the temperature of the incoming outside

air, because the conditions round the doorway are continuously changing.

Constructional aspects may also influence the need for capacity. The following guide

lines apply to a simple selection and prove to be successful in actual practice:

Favourable situation: covered shopping centre or entrance with revolving door

Normal situation: little direct wind effect, no opposite open doors, ground floor

Unfavourable situation: on a corner or a square, storeys, open staircase.

Strength of an air curtain

A properly working air curtain does not need to displace much air. The strength of an

air curtain is determined by the correct ratio between speed and width of the air

stream blown out. The air speed is determined by the turbulence in the air stream as

well. By applying the patented rectifier technology of Biddle the air stream hardly

fans out and much less air displacement is required than with air curtains without

rectifier. Apart from giving more comfort less boiler capacity is needed and the

energy consumption is lower. With an air curtain that is too strong the efficiency is

reduced, because the stream collides with the floor and part of the heat is lost.

To avoid air leakage on the sides the

unitshouldbeatleastaswideasthe

doorway.

Byusingthistableanaircurtaincan

easilybeselected.

Type

Door height

Favourable situation Normal situation Unfavourable situation

S to 240 cm to 220 cm -

M to 280 cm to 250 cm to 220 cm

L to 330 cm to 300 cm to 280 cm

XL to 380 cm to 350 cm to 320 cm

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 19 20

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Biddle CA2 Manual do Utilizador Página 10