By Frank Federman
A âpainlessâ primer about cooling fans and systems for home theaters and electronics.
|This photo shows an example of a small enclosure cooler mounted in a cabinet. This size unit is designed for installation in an enclosure or cabinet up to about 12 cubic feet in volume, typically measuring about 2-ft by 3-ft by 2-ft, with no more than one shelf or a small section of a larger enclosure. The location for a fan panel varies, depending on factors such as how close the cabinet is to a wall, whether the cabinet stands on feet, etc.|
Most home theater components are designed to run in well-ventilated areas. Unfortunately, when installing several components in an enclosed area without adequate airflow, the combined heat from the various components will shorten the life and hamper the performance of many expensive components. There are cooling products and systems that can help. For cabinet shops that handle a lot of entertainment center projects, the following information may be of use.
The three steps to successful cooling are:
1. Identify the cooling problem and the product you need.
2. Decide how and where to install it.
3. Install it.
You would probably like a little more detail, especially in Steps 1 and 2. Without getting into advanced math or thermodynamics, here are a few comments. There are formulas that determine how many cubic feet per minute (cfm) are needed in order to remove a given amount of heat. As these are difficult to apply in AV work, I have found it is easier to think about minutes between air changes. Change the air in a home theater system every few minutes, and problems go away.
Quiet, effective cooling is achieved by allowing all enclosures to breathe freely, to let air pass through slowly (and therefore quietly) and by being certain that the airflow flows where it should â over the hot equipment. Recommendations for achieving this are slightly different, depending on whether you have unenclosed or enclosed installation.
Unenclosed Installation: There are many types and styles of cooling devices, and the particular installation and size dictate which of these are most effective for a given situation. Generally, these are good rules to follow:
â¢ If the equipment is not completely enclosed but is on a bookshelf, in a corner or otherwise has some, but not enough, ventilation (i.e., a cabinet with no back and no doors), use a cooling device that sits below or on top.
â¢ Use a cooling-base type device that sits underneath the equipment if the component has bottom slots, or a top-mounted fan unit if the vent openings are on top. If you want to put a heat-sensitive device, like a DVD player, on top of something hot, use a cooling-shelf (âheat-shieldâ) product, and cool the âsomething hotâ while shielding the device placed on top. This lets you put more gear in a given area than you safely could ordinarily.
Enclosed Installation: If the equipment generates a moderate amount of heat and if the enclosure is compact, a small system-type cooling package is the solution. A computer in a kitchen cabinet or small music systems in a section of a larger cabinet are examples. In these cases, look for a cooling product with a couple of fans and grilles. These devices can be used to either pull in cool air or push out the hot.
If the enclosure is mid-size (24 to 30 inches) high and one or two components wide) and the equipment is the typical home theater assortment of a receiver or amp, DVD player, a cable or satellite box, etc., there are larger system kits available to address the size and complexity of the configuration. Quality system sets will include multiple slow-turning fans, grilles, power supplies and a control device. They should be heat-sensitive and able to automatically adjust to environment and usage temperature changes with fan speed controlled by (or better yet) proportional to temperature rise.
If the system is more ambitious, with a whole-house amp, TiVo, power conditioner, etc., look for a still larger version of the system kits with full four-fan versions of the same automatic temperature-sensitive cooling systems.
For the larger jobs, such as closets and enclosed video projectors, where you have to move the hot air up into an attic or dead space, use a system that states it is specially designed for and suitable for converted coat closets, enclosed single-chip (up to about 500 watt) projectors and large cabinets that are about the same size as coat closets.
Finally, for the largest jobs (and the most power-hungry video projectors), there are serious commercial air handlers capable of moving air tens of feet to utility areas where it can dissipate.
More Tips and Advice
Fans can be mounted in various positions while moving air in patterns that will produce reasonable ventilation, depending on the availability of space behind or beside cabinets or the presence of feet or a kick-panel, etc. If the equipment is on shelves, put holes in the shelves under the gear. If it is a rack installation, leave some open space in the rack, using vent panels. This lets cool air get in and around the equipment, so heated air can leave the rack and be removed from the enclosure.
Try to get complex air motion, i.e., side-to-side, down-to-up, front-to-back. If fans will be visible when installed (on a wood cabinet) and âlooks count,â consider products made from matching woods that are now available.
As you can see, moving air successfully in order to cool your jets, so to speak, is a precise undertaking but, done correctly, it adds stability, performance and safety to any home or office electronics installation. The best advice is to look for products from a company that specializes in cooling.
Ultimately, if the system and the installation are a bit too complicated for your employees, donât hesitate to involve a licensed system integrator who, again, has cooling and ventilating as a specialty or a significant business group dedicated to this area.
Frank Federman is CEO of Active Thermal Management, a supplier of cooling systems and products. He is happy to answer questions via his e-mail, firstname.lastname@example.org, or visit ATMâs Web site, www.activethermal.com, for more information.
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