Background
Building owners and managers worldwide are continually incurring excessive property damage and degraded indoor air quality caused by the failure to successfully remove condensate (water) from air conditioning units. These conditions are the direct result of commonly used faulty condensate drain systems. Condensate drainage is not a simple process since the pressure inside the units is generally lower (negative – a partial vacuum) than the pressure outside. Attempts to control drainage of condensate with p-traps are costly failures.
The most authoritative assessment of the condensate trap for drainage control is included in ASHRAE [American Society of Heating, Refrigerating and Air Conditioning Engineers] Standard 62-89R, paragraph 5.6.4, which reads as follows:
"Condensate traps exhibit many failure modes that can impact on indoor air quality. Trap failures due to freeze-up, drying out, breakage, blockage, and/or improper installation can compromise the seal against air ingestion through the condensate drain line. Traps with insufficient height between the inlet and outlet on draw-through systems can cause the drain to back-up when the fan is on, possibly causing drain pan overflow or water droplet carryover into the duct system. The resulting moist surfaces can become sources of biological contamination. Seasonal variations, such as very dry or cold weather, may adversely affect trap operation and condensate removal."
Consequences of Trap Failures
Despite this assessment of the condensate trap, it remains the choice of the industry as a means of drainage control. The building owners and managers suffer the consequences. Some of the many trap failure modes identified by ASHRAE are illustrated in Figure 1. These failure modes, which occur frequently, allow condensate blowing and flooding as illustrated—causing property damage and air contamination. Since all the air in a building passes through the air conditioning unit at a rate of several times per hour, the circulated health threatening pathogens inevitably expose occupants to degraded indoor air quality, as indicated in Figure 2.
Figure 1
Figure 2
The air conditioning units in your buildings are, undoubtedly, equipped with condensate traps. If they have been in operation for at least 5 years, the p-traps have probably failed several times and have been removed, cleaned, or replaced. And the units will likely exhibit conditions like those illustrated. If so, this deterioration can be stopped by having your service personnel install the CostGard™ Condensate Drain Seal. In new construction, simply instruct designers to specify this drain seal.
