Positive Pressure Low-profile Air-Trap

A new concept in condensate trap design permits condensate removal from AC or other condensing equipment while blocking airflow all year and requires only 2 7/8″ height for positive 0-40″ WC pressure (PLP-084) and 2″ for the smaller 0 to 5” WC pressure (PLP-051). They will never “dry out” or freeze because they do not  depend on water to seal, only fan pressure.

For a hundred years the P-Trap, a carryover from use on toilets and sinks, has been used on AC equipment to prevent air loss. Unlike the P-Trap, the PLP was designed specifically for HVAC equipment and does not require standing water to prevent air leakage. AC equipment produces condensate mostly during summer. The remainder of the year little or no condensate is produced, and the P-traps are dry most of that time. When they do have water, the bottom of the trap is prone to develop sludge and growth. The PLP operates dry when no condensate is being produced and uses a levered, horizontal pancake designed float-valve with a mechanical advantage about a pivot point. This allows the PLP to require less than 2 7/8″ inches of height for up to 40 inches WC pressure instead of the 8 to 60 inches required for a standard P-Trap.

Because positive pressure, resulting from blow through units, does not create the problems associated with negative pressure condensate traps, such as sucking air and blowing condensate over the cooling coil compartment, positive pressure traps are many times left out of the drain line. This results in air that has just been cooled or heated being blown to ambient and unconditioned ambient air of equal amount being drawn into the space through the building envelope or ducting. Another problem facing engineers and contractors that prevent using a positive P-trap is the height required by the trap to enable it to contain enough condensate to prevent dry-out and leakage of conditioned air during the entire year. Also, there are essentially no universal mechanical codes that require traps on condensate lines that would prevent loss of conditioned air. The PLP-Series Air-Trap solves all the problems just mentioned.

PLP shown installed with a larger and smaller pipe using a connector and bushing respectively.


The Air-Trap™ concept has been incorporated into IAPMO IGC 196-2018 Standard for Condensate Traps and Overflow Switches for Air-Conditioning Systems.

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Scandinavian Distributor:

Air-Trap Scandinavia

C/O Energiteknik Lolland ApS  

Jesper Frederiksen

Klostervænget 1a

4900 Nakskov

+45 29440005

The FCN-Series Air-Trap™, N-Series Air-Trap™, P-Series Air-Trap™, RLC-Series Air-Trap™ and Union-Strainer™ are trademarks of Des Champs Technologies. All products are developed and manufactured by Des Champs Technologies, Virginia, USA.