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F&T trap piping problem

Hello Guys, I work for a mechanical contractor and I have not posted on here in many years but I do look up information on the website but I am stuck on this one.
This is a small school. 2 pipe steam Weil McLain series 80, natural gas 10 section boiler. The system has 2 motorized zone control valves with a boiler feed pump. The one zone has a water seal before it enters the boiler feed tank the piping goes under a doorway and comes back up. That one zone splits into 2 mains which have F&T traps at the end but no main steam vents. The one main has condensation backing up badly I drained at least 40 gallons today. The F&T trap is a Barnes and Jones FT2015-3, and the piping out of the outlet goes upward to tie into the dry return. The static head is minimal only 4-6” drop, 50% of the insulation is missing and there is no steam pressure to help the condensate along after the zone valve close. This clearly has been a issue because there was a boiler drain on the 3/4” tap on the wye strainer with a bucket hanging on it. I really do not want to change the F&T trap out because I don’t think it is going to work properly anyway. The other main on this zone they have room to drop the T&F trap but that main is not experiencing the same issue.
Is there a trap I can use in this situation that will be better to use? Can you install a main air vent on the inlet pipe to the F&T trap instead of trying to pipe in a tee on the main? Any help or ideas are greatly appreciated.


  • AMservices
    AMservices Member Posts: 610
    Put main vent on the f&t. Use the steam inlet on the trap not being used.
    You got the right idea.