Contractors & Installers



Air conditioning and plumbing contractors are well aware that p-traps in condensate drain systems are subject to frequent failures. You have witnessed the severe water damage and contamination to air conditioning units and the damage to surrounding property caused by these failures. The seriousness of these failures is not fully appreciated by many in the air conditioning industry.  However, the fact that this situation is real is supported by the following assessment by 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. Your customers, 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.


Failed P-Trap Examples - Figure 1 Consequences of Trap Failures - Figure 2

Contractor’s Role

Air conditioning and plumbing contractors usually have the responsibility for installing and/or maintaining condensate drain systems. 

Installation: When condensate drain systems are defined by designers, a p-trap is commonly specified and the geometry defined. When so specified, the contractor’s installation task is relatively simple. Oftentimes, however, the specification simply states that the drain system “shall be trapped” or it makes no reference to drains systems. In either case, contractors must select and install a trap because most plumbing codes simply require them to do so. Unfortunately, it makes little difference whether the trap is designed or selected randomly. The p-trap exhibits so many failure modes that, regardless of the geometry, it is certain to cause damage to the air conditioning system, the building, the building contents and degrade indoor air quality.

Maintenance: The only remedy the industry offers to these costly problems is improvement in system maintenance. The fact is, satisfactory maintenance of such systems is virtually impossible. Even with the best possible trap geometry, the continual maintenance effort required to: (1) prevent flow blockage, (2) keep water in traps during winter operation, (3) prevent trap freeze-up during wintertime, and (4) ensure the trap is full at startup for summer cooling is at best unrealistic. Add to these the design deficiencies to those of randomly selected p-traps and effective maintenance is simply not feasible.

This situation places contractors in an unenviable position. They are forced to install drain systems which are failure-prone and cannot be successfully maintained. Evidence that contractors recognize this is reflected in typical contracts they offer to building owners, which often include the following warranties: compressors and coils – 10 years; condensate drain - 60 days. See 60 Day Warranties Acrobat

Fortunately, there is a proven effective and reliable solution to condensate drainage problems: The CostGard™ Condensate Drain Seal. A short video, accessible from the home page of this website, shows typical damages caused by failed condensate traps. It illustrates how the CostGard™ Condensate Drain Seal operates, and how it prevents these damages. To review the contrast in maintenance requirements for the CostGard™ Condensate Drain Seal system and the condensate trap, view this hyperlink: (Trap vs. CostgardTM Condensate Drain Seal) Acrobat

Some economic reasons why the air conditioning and plumbing contractors may want to take advantage of the features the CostGard™ Condensate Drain Seal offers and other advanced technologies are included in Reference 1, More Effective Performance Standards in 10 Steps Acrobat

Reference 1:  “More Effective Performance Standards in 10 Steps” by Mike Callahan, in the HVAC Business magazine, October 2009.

Other topics in this website that provide additional information about the features of this drain seal are listed below;