If your business is like most, you probably have a rooftop air conditioning unit. Generally these work well and can perform without problems for years with regular annual maintenance. Occasionally, though, moisture issues occur that are caused by your rooftop unit. The following guide can help you spot the potential for problems so you can get them fixed before you have a disaster on your hands.
Issue #1: Improper supports
The unit should not sit directly on the roof. This can lead to all sorts of problems, including ponding water from rain or condensation runoff around the main unit. Many modern units are placed on support rails, which leave an air space beneath the unit so water can drain and dry quickly, as well as distributing the weight of the unit appropriately. Other units may be placed on an elevated foundation pad. The roof should slope upward slightly toward the pad so that rain and condensation runs off instead of ponding around the base of the pad.
Issue #2: Weak duct seals
The duct work coming out of the unit and entering into the building is exposed. Moisture can easily get into the joints between the ducts, collect in the ductwork inside the building, and then cause water damage where it drains out. The exposed ductwork should be sealed so that it is watertight. Once sealed, it should be inspected during regular service visits to ensure it hasn't degraded and doesn't need to be replaced.
Issue #3: Condensate draining
Condensation is a natural byproduct of any AC unit, and there can be an especially large amount of it for a rooftop commercial unit. The drainage hoses typically lead to a drain that takes the condensation off the roof and to the main sewer line the the exterior drainage system. Occasionally these lines can become blocked by algae growth or other debris. When this happens, the moisture backs up, pools on the roof, and leads to leaks. Check that the condensation is draining properly and that all drains and hoses are clear during your regular inspections.
Issue #4: Traffic damage
Flat commercial roofs aren't generally intended for regular foot traffic. This can weaken the roofing material and lead to leaks in the building, so most flat roofs have a few reinforced paths that lead to the rooftop appliances to avoid this problem. Most business owners depend upon the building maintenance crew to perform normal monthly service and only call in HVAC professionals when there is a problem. Make sure that the safe paths are clearly marked on your roof so both your maintenance crew and any contractors can easily find the least damaging way to reach your rooftop unit.
For more help with AC leaks, contact a commercial air conditioning contractor such as Ragan Mechanical Inc.