Overheated Telecom Closets Put the Equipment at Risk
If the building is still in the design and planning stages, the closet’s cooling requirements can be taken into account and a dedicated air-conditioning system specified.
In the case of many existing buildings, electronic equipment is frequently installed in a converted clothes closet or small storage room. In the summer months, the air conditioning system may provide adequate cooling, and no further thought is given to the equipment. As the weather turns cool, however, and the building’s HVAC system switches to heating instead of cooling, the situation can dramatically change. Since electronic equipment generates heat, and the server closet may be very small, the temperature can quickly rise. Unless adequate air conditioning is provided to the closet, there is a high risk of heat-caused equipment failure and possible costly damage. For many businesses, system downtime can be even costlier.
Electronic equipment usually requires a cooler ambient temperature than the human occupants of a building. As a result, even during the summer months, when the building’s main air conditioning system is on, electronic equipment may not receive adequate cooling to ensure long-term reliability. Although there may be no outward signs of overheating, and the equipment may not fail immediately, even moderately excessive heat can shorten its life cycle. More importantly, if the air conditioning system is turned down during off-hours, on weekends or on holidays, the temperature in equipment rooms can quickly soar. If the equipment runs 24/7, it can easily be affected. In these situations, a new class of self-contained, ceiling-mounted industrial spot air conditioners offers an efficient and cost-effective solution.
The Solution: Self-Contained Spot Air Conditioners
The introduction of a relatively new class of self-contained commercial air conditioners, called spot air conditioners or spot coolers, provides a convenient, more efficient and more cost-effective alternative to precision-cooling systems. There are two basic types of spot air conditioners: air-cooled or water-cooled. Water-cooled air conditioners are more efficient than air-cooled ones, but they use high-pressure water lines that can leak. Consequently, like evaporative coolers, they are usually considered unsuitable for use with electronics equipment. Air-cooled spot conditioners are the choice for cooling telecom closets.
How Spot Air Conditioners Work
Self-contained spot air conditioners combine both a compressor and evaporator coil in a single unit. Within the unit, cold refrigerant flows through copper tubing from the compressor to the evaporator coil. A fan blows over the coil, pushing cold air out. A second fan pushes hot exhaust air out through the system’s built-in flexible ducting, which is usually directed into the crawl space above a drop ceiling. Excess moisture removed from the air collects in a small condensation tank, which can be emptied manually or, with most models, automatically via a pump.
Portable vs. Ceiling-Mounted
Spot air conditioners are available in both portable floor as well as ceiling-mounted models. Even though portable models are primarily designed for applications where they can be quickly and easily moved, they are often used in permanent installations as well. Their small size makes them ideal for use in applications where space is at a premium, such as small- to medium-size server rooms. Most server closets do not have even the small amount of floor space that a portable spot air conditioner requires. In such cases, a ceiling-mounted model is usually the only practical choice.
Benefits of Ceiling-Mounted Spot Air Conditioners
- Quick and easy installation - Unless there are special circumstances, a typical installation usually takes two installers working together for only about four hours. Spot air conditioners consist of only a single, pre-charged unit. This means that they do not require sweating or brazing of copper connecting tubes or refrigerant charging, as precision-cooling systems do. These procedures add significantly to installation costs.
- Smaller footprint - Ceiling-mounted spot air conditioners are considerably smaller than precision-cooling systems, so they are easier to fit into the limited crawl space found above most server closets.
- Convenient voltage - ceiling-mounted spot air conditioners are available in 115 V models, whereas precision-cooling systems are generally offered only in 230 V configurations, potentially increasing installation costs still further.
- Flexible placement of air supply and return - Ceiling-mounted spot air conditioners use flexible air ducts for both supply and return. This allows the air conditioner itself to be conveniently placed anywhere in the crawl space, independent of where the supply and return need to be located. Also, the location of the supply and return can be easily changed whenever necessary, to eliminate any new hot spots that may result from changes in equipment configuration.
What to Look for in a Ceiling-Mounted Spot Air Conditioner
When choosing a ceiling-mounted spot air conditioner, here are three important criteria to look for:
1. Quality of Manufacturing: Air conditioning must be reliable, especially when critical electronics or telecom equipment is involved. Look for a system that is built to the highest quality standards. Specifically, check to see if the fan motors are fully enclosed in protective housings to prevent dust from building up. Dust that accumulates on the motors can absorb moisture, leading to corrosion or electrical shorts.
Next, look at the sheet-metal panels to see if they have stress-relief notches at the bends. Also, are the panels attached to the frame at load-bearing points by machine screws and weld nuts, or by lighter-duty sheet-metal screws? Is the weight of the fan housing supported by a sturdy, interior frame panel, or only by a lighter cover panel?
Another important area to pay attention to is the refrigeration unit itself. Is it hermetically sealed, or does it have service valves, which are prone to leaks? Are the refrigerant pipes connected by reducers and expanders, or by pinching and brazing? Pinching and brazing restricts the flow of the refrigerant, reducing cooling efficiency and long-term performance. In addition, the connections created using this method are weaker and more subject to vibration-caused stress cracks and subsequent leakage. Such quality-oriented details are telling indicators of high-quality equipment that is designed and manufactured with long-term reliability in mind.
2. Verified Performance: When comparing performance specifications, check to see if the manufacturer has its equipment evaluated by a nationally recognized, independent testing laboratory such as ETL (Electrical Testing Laboratories) or UL (Underwriters Laboratories). Unlike the ETL Listed or UL Listed marks, which are safety certifications, the ETL Verified mark is a performance certification. ETL Verified means that the equipment in question has been independently tested and found to perform at the levels the manufacturer says it will, using actual performance data, not calculated data. This type of performance verification is another indicator of high quality.
3. Established Manufacturer: Look for a company that has established itself for many years in the industry and stands out as a leading manufacturer of air-conditioning equipment. This is a good sign that the company will be around to support their equipment well into the future. Also look for a company with a broad distribution base and a large number of dealers who will support and service their equipment throughout North America and globally.
Article courtesy of Movin Cool, Inc.