How Water-Cooled AC Units Work and When to Use One

Portable air conditioning units are a good solution when you have a relatively small space that needs some extra cooling — a restaurant kitchen, a server room, a hospital room, a telephone switch room or a retail store dressing room, for example. However, water cooled units do not need to be vented where air-cooled AC units must be vented, and that’s not always feasible.

When you don’t have a window and can’t duct hot air, and you do have a nearby water source, a portable water-cooled AC unit may be an excellent choice, according to Scott Kubota, facilities maintenance specialist at United Rentals.

Water-cooled AC units attach by hose to a faucet that serves as the water supply. The faucet can be as far as 75 to 100 feet away or greater in some cases. The water flows through the condenser coils to remove heat from the refrigerant inside the coils. The heated water is then sent out through another hose into a drain. A water cooled unit does not introduce water or humidity into the area being cooled.

No ducts are needed, which avoids the situation air-cooled units sometimes create in small rooms that lack make-up air. This situation is known as negative air pressure and can freeze up the AC unit.

Speed and efficiency

If you’re looking for the fastest and most energy-efficient way to cool a room, especially a room with a high ambient temperature, a water-cooled AC unit is often a better choice than an air-cooled portable AC.

A water-cooled unit uses less electricity because it has only one blower motor, whereas an air-cooled unit has two. It also offers greater cooling capacity. A 5-ton water-cooled single-phase unit requires only 30 amps compared to 50 amps for a comparable air-cooled unit.

When an air-cooled AC rejects heat through a duct, it makes the duct warm, emitting heat into the space. Water-cooled units cool faster because they don’t discharge any hot air into the space. They cool about 500 to 600 square feet per ton of AC power.

Common concerns

Some building managers have been hesitant to use water-cooled AC units because they worry the connection between the hose and faucet will leak, risking damage to floors and equipment. (Joining the hoses to the unit has usually required a wrench and some elbow grease.) But with the water-cooled AC units United Rental provides, that risk is eliminated.

“We have quick-connects that just about anybody can use to put the hose on; it is clean, simple, doesn’t require a wrench and is leak proof,” Kubota said.

Water usage is another common concern. It varies by job and the temperature of the water (the colder the water, the less is required), but it averages in the neighborhood of half a gallon per minute per ton of AC power. With 1,000 gallons of water costing about $1.50 on national average, the cost of operation isn’t high in most areas. In addition, water-cooled AC water only flows when the unit’s compressor is on. When the unit’s compressor is not running, neither is the water. Therefore, when the room reaches the desired temperature, the water stops running and that conserves water and reduces operating costs.

A temporary equipment provider can help you determine the best temporary cooling solution for your specific circumstances, as well as the applicable rules and regulations related to your site and to your situation.

To learn more, visit our United Rentals Climate Solutions page, or give our team a call at 833.426.1188