Condensate leaks can be caused by a number of factors. For starters, it can originate from a cracked or corroded condensate drain pan. The PVC drain line can also form cracks or holes due to stress, accidental impact or age. Clogs caused by debris or mold can also cause leaks through an overflowing condensate drain pan.
Book Online Now! This performance advantage, however, comes with a costly penalty for building owners and managers, in the form of dry trap syndrome. The primary purpose of the P-trap in a plumbing system is to form an isolation seal between that system and the sanitary sewer, thereby preventing sewer gases and other contaminants from entering the building.
For this application, the operating conditions are such that the P-trap provides an effective seal. Generally, the only pressure across the P-trap seal is that resulting from the vapor pressure of water and sewer gases, and that is relatively small.
P-traps in this type of system are continually supplied with adequate water to form a reliable seal. And, frequent surges of water through the trap that occur — for example, in sinks, lavatories, and water closets — purge the traps and minimize the potential for trap blockage. The drain seal on the condensate drain line of a draw-through hvac system has an entirely different purpose.
Moreover, the operating conditions are vastly different and much more demanding. Contrary to what many in the industry seem to believe, the need for a seal on a drain of an hvac system has nothing to do with connection to the sanitary sewer.
In fact, all three of the regional plumbing codes in this country prohibit direct connection of the condensate drain line to the sanitary sewer. A drain seal is required on a draw-through system because the drain pan operates at a negative pressure partial vacuum. It is these conditions that cause the malady — property damage and health threats — referred to in the industry as dry trap syndrome.
There are two primary reasons why conventional condensate traps are frequently dry and ineffective: condensate evaporation and condensate leakage caused by freeze-damaged traps in outside locations. Anytime an hvac system is not providing cooling — and no moisture is removed from the air — for a period of a few weeks, evaporation will destroy the seal formed by condensate.
In addition, at most latitudes in this country, condensate in a trap in an outside location is subjected to freezing conditions, which can damage the trap and destroy its seal. Under these circumstances, the level of maintenance effort required to prevent dry trap operation is generally regarded as impractical. In fact, in some instances, successful maintenance is virtually impossible. During winter operation, dry trap syndrome has an effect on both human comfort and health. The ingestion of odorous gas sometimes from the sanitary sewer occurs frequently.
Reported incidences are widespread. The ingestion of toxic gas occurs less often but when it occurs, the consequences are far more serious. Carbon monoxide CO, a product of incomplete combustion in water heaters, furnaces, automobiles, etc. Incidents of CO poisoning are reported frequently as news items. Among these, there is documented evidence of persons being poisoned by carbon monoxide introduced into inhabited space through an hvac system operating without a drain seal.
One remedy for this malady, although maintenance intensive, is to manually fill the trap with water — frequently. A P-trap is needed to block air and allow condensate to drain properly. What type of furnace is running to this as well. High efficiency furnaces create an acid condensate that should not be discharged to the ground. For the most part evaporator condensate traps are required by the manufacturer help to meet the energy efficiency standards as without it air will blow through that hole.
If there is no trap…note it and tell them to still clean the line occasionally. Hi Larry, I believe there is a trap and vent added to the condensate drains. I saw this first hand on a commercial air handler I installed when I was in the field. I found water had filled the bottom pan completely simply because I did not pipe it correctly. Thanks for the explanation, Kevin. Is the evaporator coil up or down stream from the indoor fan?
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