ACHRNEWS

Portable cooling needs on the rise

June 1, 2000
“My computer room air conditioning just went out! If the computers overheat, I’m out of business!”

This is only one of the frequent scenarios being played out in the temporary portable a/c market. When breakdowns occur, time is of the essence, and this is when a rental company that specializes in portable air conditioning, really shines.

Having the proper equipment in sufficient quantity and in good working order, along with the ability to quickly deliver and assist with the installation, is essential. Today, portable a/c units are used in a variety of markets to fix a growing list of difficult cooling problems.

The units are fast and easy to install; many units plug into a standard 115-V wall outlet, other units use electrical quick connects and are fused at the unit. The units are portable and easy to move about, allowing you to direct the cold air precisely where it is needed most.

Portable units that are rugged and dependable, inexpensive to operate, and thermostatically controlled can provide a cost-effective alternative to central systems.

Solving the emergency cooling needs of critical heat-sensitive equipment such as telephone switch rooms, computer rooms, and electronically controlled machine tools during unplanned downtime has been the mainstay of portable a/c rental companies for years.

Today, as businesses continue to add more employees and office equipment into existing buildings, the hvac system becomes more heavily loaded. It is often not feasible for these companies to upgrade to new, larger cooling equipment, particularly if the building space is being leased.

Portable air conditioning has become an economical method of providing additional cooling precisely where and when it is needed most, to cool either people or equipment.

Growing applications

It is common for large, commercially managed buildings to have their central cooling systems shut down during nights, weekends, and holidays in an effort to save energy costs. Tenants are often charged $100 to $200 an hour to have the cooling turned on during irregularly scheduled hours.

Portable air conditioning is ideally suited to provide inexpensive cooling precisely where it is needed to prevent overheating of people and equipment during these scheduled downtimes.

Many units have programmable thermostats, allowing for the units to automatically turn on and off at predetermined times, providing hands-off, worry-free operation.

Conversely, buildings that currently run the cooling system around the clock in order to cool one or two computer rooms at night and on weekends could realize substantial savings by using portable air conditioning units to provide localized cooling to these areas. This would provide an opportunity to shut down the central system, saving money and energy.

Industrial users have developed their own unique uses for portable a/c. Cooling confined spaces during repairs, such as heat treat ovens and storage tanks, can reduce downtime by days.

The cooling of certain manufactured parts and heat-sensitive production equipment can dramatically increase productivity in many applications. Plant personnel are cooled, not only to increase productivity but for safety concerns as well.

Special events is the fastest growing market for the use of portable a/c. These applications consist mainly of cooling tents but vary greatly in the size and scope of the applications. Tents as large as 20,000 sq ft are erected for corporate functions, charitable fund raising activities, and entertainment facilities during professional sports tours as well as other special gatherings.

Events of this magnitude require large cooling units and power-generating equipment to do the job. The more common smaller tents, such as those used in a backyard wedding, can often use small portable units placed inside the tent. These portable units provide cooled air as well as dehumidification.

Portable air conditioning applications can be placed into three categories: emergency breakdowns, planned temporary usage, and permanent applications.

Emergency breakdowns require an immediate response, day or night, 365 days a year. When a building a/c system crashes, it is usually not practical from an economic standpoint to temporarily cool the entire building. End-users will need to prioritize their needs.

Perhaps there are critical areas, computer rooms, workstations, etc., that require cooling, while less sensitive areas such as hallways, rest rooms, and storage space may not require cooling.

How do we get cooling precisely to these critical areas? The most common method is to use mobile air-cooled units and place the units directly into the environment being cooled.

These types of units are available in sizes from 1- to 5-ton capacities. This method offers the greatest flexibility and the easiest and fastest installation.

Important considerations

When using air-cooled units, it is absolutely essential that there is an adequate space to vent the condenser air.

In many instances the condenser air can be vented into the above-ceiling plenum. This plenum space must be large enough to handle the volume of condenser air.

This warm air would ideally be able to escape to the outside or would be able to disperse itself evenly throughout the entire plenum space. Windows or other suitable openings to the outside are ideal to use if we are fortunate enough to have them available.

There are applications where there is no way to remove the warm condenser air, perhaps if the ceiling plenum is simply too small and there is no access to the outside. For these circumstances, air-cooled units would actually add additional heat into the space we are trying to cool.

To overcome this problem, mobile water-cooled units can be used. These units conveniently connect to a water source by way of a hose kit with special fittings. This simple and quick method of installation eliminates any need for ducting the warm condenser air. These units are available from 1- to 5-ton capacities.

Large open areas are often better served using large area units. These units are designed to be placed outside. The supply air and return air can be ducted directly to the area to be cooled or can be tied into the existing ductwork.

In either case, flexible duct is used to bring the air to and from the unit. Three-phase electrical power is required to operate the larger units.

To facilitate the installation, the unit should be equipped with cam locks or other suitable quick connecting electrical devices. In addition to the quick connects, a circuit breaker or fused switch should be an integral safety component mounted in the unit.

These three features, the ability to accept flexible duct, electrical quick connects, and integral circuit protection are necessary to achieve an easy, fast, inexpensive installation.

The life of a portable air conditioning unit is a difficult one. Being moved from location to location, loaded and unloaded on and off of trucks, withstanding the bumps and potholes along their travels, installation, dismantling, and reinstalling again and again is difficult.

For a portable unit to be dependable and rugged enough to successfully perform its job, it must be designed and built, from the ground up, to be a portable unit. The duty cycle and environments experienced by portable units are too severe for other units to withstand, no matter how well they are modified.

Nearly every sizable metropolitan area has at least one company that specializes in portable air conditioning units. It is important that the people you work with are experienced and skilled in the hvac field. Applying portable units is often as much an art as it is a science and there is no substitute for experience when you are trying to overcome difficult cooling problems.

Some of the important issues you should consider when selecting a supplier of portable a/c equipment include:

  • Do they have the ability to modify equipment to meet or enhance the requirements of the job?

  • Are supplies necessary for a proper installation, such as duct and flanges, available?

  • Is the equipment clean, presentable, and well maintained?

  • Is the delivery of the units conducted in a timely manner with trucks equipped to quickly and easily handle the job?

  • What happens if you experience problems while using the equipment and is 24-hour emergency service available?

Customers no longer need to suffer with the frustrations and anxiety caused by poorly operating, inadequate, or broken down air conditioning systems. Portable air conditioning offers an effective proven method to solve a wide variety of cooling problems.

Portable air conditioning has experienced significant growth over the past 10 years. As awareness continues to grow, and companies continue to benefit from its many uses, this positive trend will continue.