verheating is prevented when there is sufficient cool air flowing through the cabinet to carry away any excessive heat.

In the absence of any air motion, hot air will build up in a pocket around each heat producing component in a cabinet. If this is allowed to happen, the temperature will keep rising until the system has fried itself. What prevents overheating is movement in the air. More specifically, it is the movement that allows cool air to flow in and replace the warm air.

When a stream of cooler air meets a pocket of warmer air, the warm air is caused to rise toward the top of the cabinet. A steady flow of cool air into a hot component system thus creates an ongoing, upward stream of warm air. This process is called convection.

Passive ventilation

Natural convection, as the name indicates, is the process of air replacement that takes place due to natural turbulence in the air. If your component cabinet has sufficient openings for cool air to flow in and hot air to escape, then your components will be cooled to some extent just due to the fact that the air is set in motion by any movement in the room. Whenever the air is stirred up, cool air will make its way into the cabinet and cause a flow of hot air out of the cabinet. This process is also known as “passive ventilation” – “passive,” because it takes place without any effort to facilitate it.

StudioTech’s Ultra cabinets are designed to facilitate such a process of passive ventilation. The mesh screen door, side vents, and generous rear openings jointly make possible a substantial flow of air right through the cabinet.

Creating an effective airflow

To achieve the most effective passive ventilation you must try to create a “chimney effect” by leaving an unobstructed vertical column of air where hot air can freely rise and escape. Ultra U-48 and U-60 cabinets are designed to create such an effect. Rather than reaching all the way to the sides or rear of the cabinet, the shelves inside are situated in the space between four corner pillars. This design leaves narrow “chimneys” on both sides and at the rear. However, the relatively narrow design of the cabinets places some limitation on the effect.

To ensure that heat can freely escape each component, leave some space between shelves. If you pack the interior of the cabinet densely, airflow is restricted and pockets of hot air will more easily form around your components.

The upward motion of warm air is created by the temperature differences (called “gradients”) between cool and warm air. To create the most effective airflow, you should strive to place the hotter components at the top of the cabinet. This way you create the greatest temperature contrast, and keep the warmest air closest to the exit.

Also make sure to keep the surrounding room temperature down. In order for cool air to flow into the cabinet, there must be cool air in the surroundings. And in order for hot air to rise out of the cabinet and escape, the outside surroundings must be cooler than the escaping air. To maintain the maximum operating temperature of your components at 85^o F it is recommended that you keep the air in the surrounding room at 75^o F.

Ultra cabinets

Here is how you make best use of the passive ventilation features built into your Ultra cabinet:

• Create a “chimney effect” by leaving vertical columns of air unblocked.
• Leave space between shelves.
• Place the hottest components toward the top of the cabinet.
• Keep the surrounding room temperature at or below 75^o F