Portable Air Conditioner
Given the static nature of most data centers, cooling infrastructure is often integrated into the physical structure of the building. But what happens when built-in AC is not enough to adequately cool the environment or, worse yet, goes down?
The average server puts off approximately 1,200btu, so IT managers know it is not long before temperatures can reach critical highs, even to the point of damaging computer systems. When disasters such as an HVAC system failure strike, managers often turn to portable AC units during the interim to maintain safe temperatures in their data centers.
Today IT managers are also more likely to change office configurations, often adding numerous electronics, which generate a significant amount of heat. In older buildings, air conditioning systems were not designed for the high heat load per square foot that the modern wired office presents.
For these reasons, portable AC systems are becoming more popular as alternatives to permanent installations as well as wise investments for HVAC failures. There is nothing wrong with buying a portable, says Mike Renier, vice president of sales for KwiKool. He stresses portables a/c cost effectiveness vs. making changes to a permanent system.
Convenience, flexibility, and ease of use also factor into the choice for portable AC units. You wheel it in, plug it in, and turn it on. It is very simple, says Eddie Stevenson, product marketing manager at MovinCool.
Portable AC systems are ideal for offices, schools, healthcare, and other facilities with servers, routers, telecom, or other heat-sensitive equipment and workspaces, Spot Coolers has portable air-cooled, water-cooled, and split AC units.
Different models from 1 to 10 tons of capacity in unitary, split-system, and water-cooler and air cooled units are available in the market.
Size Matters
Prior to purchasing a portable AC unit, it is extremely important to calculate the total heat load. An Improper sizing of air conditioning systems is a disaster,as warns Renier.
Garth Tagge, vice president of sales at Spot Coolers, the leading supplier of portable AC in the United States, explains there are two facets to determining total heat load: heat generated by equipment, which is known as equipment load, and the heat in the room from radiant sources such as electrical wiring, windows, floors, and people, known as room load.
Equipment load can be calculated by adding up the wattage of each device and converting it to btu, a measure of heat. Wattage can be found either in the device’s manual or by multiplying amps with voltage, both often found on the model plate. For example, most servers operate with 120 volts and consume 3 amps, meaning they generate 360 watts. For every watt consumed, 3.41btu are generated. To convert watts to btu, multiply by 3.41, which would result in 1,227btu of heat per hour per server.
Calculating room load is also relatively simple. The rule of thumb is a typical commercially built 500-square-foot room with an 8-foot ceiling experiences a ton of room load and therefore requires a ton of cooling. This ton of cooling is for normal room and people loads. Add a copier or any heat-generating equipment, significantly more people than a room is designed for, or windows, and that load increases.
Once the room load is known, you merely add it to the equipment load. This yields your total internal load, or the amount of air conditioning you need to overcome the heat generated within the room.
Tonnage is another term often used when describing heating and cooling capacities. There are 12,000btu in a ton. This means that to cancel out 12,000btu of heat, 1 ton of cooling is required.
Buying Tips
There are a number of variables to consider when considering portable AC units and they are as follows:-
Total heat load from equipment. How much heat does the equipment within the space generate? “The equipment load is almost always the biggest heat source in the room,†says Tagge.
Secondary heat load from the room. All interior rooms have hidden heat sources referred to as “room loads.†They are a result of heat generated from electrical wires in the walls, lighting, people, radiant heat from windows, and heat from adjacent rooms and floors.
Condensate disposal. All AC units wring moisture from the air, known as condensate. Considerations have to be made on how the condensate will be removed. Some units have collection buckets that must be frequently emptied. When they fill up, they shut off the AC unit to prevent flooding. Equipment room AC units are typically operated around the clock. Emptying buckets on nights and weekends would require someone to always be there, so most are equipped with a pump to continually dispose of the condensate. “The biggest challenge to adding a pump is finding a source for draining the condensate,†says Tagge.
Power requirements. The smallest portable AC units operate on 110 volts. As such, they can typically use standard house power. However, units greater than 18,000btu or 1.5 tons use higher voltages, such as 220 or 460 volts. You will want to make sure there is the availability of this power once your loads exceed 1.5 tons.
Adequate space. Most portable AC units are placed directly in the room to be cooled. You will want to check the room for adequate space for the equipment, as well as ensure that where you place the unit allows for adequate and even airflow. Placing a unit behind something that blocks or deflects the air might create hot spots or even inadvertently shut down the unit.