The CostGard™ Condensate Drain Seal was developed specifically to replace the failure-prone p-trap commonly used on blow-through HVAC systems. Unlike a draw-through system, the fan in a blow-through system blows air through the cooling coils creating a positive pressure in the drain pan compartment as shown in Figure 1. Positive pan pressure is favorable to condensate removal, and the ingestion of outside air through the drain line is not possible. However, a p-trap on a blow-through system is subject to the same issues as found on draw-through systems. Condensate flow can be obstructed by algae growth and other debris causing condensate pan overflow and property damage.
How the system operates can be explained by referring to Figure 2. Condensate and air leaving the drain pan enter Part A. Both then pass through the mitered elbow array, Part C, into Part B. From there, the condensate and a portion of the air pass to the drain outlet and on to the condensate disposal place. The remainder of the air passes into Part D and out through the vent. As the condensate and air pass through the mitered elbows, there is little resistance to condensate flow. Indeed, condensate flow is aided by the positive pressure in the drain pan and flows freely through the system. At the same time, these mitered elbows restrict airflow such that the velocity leaving the unit is far too low to cause entrainment and blowing of condensate. In addition, the air turbulence in the mitered elbows creates a scrubbing effect which prevents blockage by debris and algae growth.
When used in place of a p-trap, the CostGard™ Condensate Drain Seal offers building owners and managers a number of benefits in terms of operating cost and indoor air quality, including the following: