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Hoffman H style Float and thermostatic trap at a brewery

scottnjr
scottnjr Member Posts: 60
in Strictly Steam
Hi all,
I am a mostly residential hvac tech. Therefore I don't have much experience with f&t traps, but I understand how they work. My friend owns a brewery, so naturally I volunteered to solve a problem since it involved free craft beer. He has a steam boiler with pumped return. The vent from the condensate pump started spewing steam. I said "sounds like a trap stuck open or bad." So I narrowed it down to 3 possible traps, all Hoffman H type the were trapping mains. We ordered one and replaced the one that was spewing. I probably screwed things up though by removing the guts of the new one and replacing the old while leaving the old body in place. I started it up and at first all looked good, then after 30 minutes or so the vent went to spewing again. I cracked the union on the outlet of the three traps, the other two were quiet and dripping a little condensate, and the new one was spewing steam. Is the new steam trap bad, or did I cause the float valve to hang open by replacing the guts like I did? is there any trick I should know? I'm going back tomorrow to disassemble it and look. I'm guessing it's the float hung up and not the brand new thermostatic trap. Any advice?

Comments

  • Big Ed_4
    Big Ed_4 Member Posts: 2,973
    I don't know if I want to tell you ? Are we getting some of that free beer ?

    There was an error rendering this rich post.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,251
    @scottnjr

    Sounds like you did the right thing. It's common to buy new parts and leave the old trap body in place.

    Did you replace the valve seat? If not that could be the problem. No trick to it just replace parts and make sure the assembly is relitively clean
  • scottnjr
    scottnjr Member Posts: 60
    big ed, just come with me tomorrow lol.
    ebebratt: the valve seat comes with the guts of the trap, so yes.
    I'm wondering if the the float isn't stuck. maybe I hung it up
  • Sailah
    Sailah Member Posts: 826
    Most of the common H pattern trap faceplates from Hoffman, B & J, Tunstall, Sarco, Watts (not Armstrong or Mepco) are basically interchangeable and yes you can put them in upside down. The air vent should be on the top, float on the bottom. Also be sure that the trap body is installed correctly, inlets should be on top, outlets on the bottom. I've personally seen them piped in upside down and they don't work very well like that.

    Very common to leave old trap body in place and add new head unit. Just be sure gasketed surface is clean and it's a quick job.
    Peter Owens
    SteamIQ
  • Pumpguy
    Pumpguy Member Posts: 691
    What size is the orifice for the float valve? If too large for the load, there could be a seating problem. Did you check for good seating when the valve is closed?
    Dennis Pataki. Former Service Manager and Heating Pump Product Manager for Nash Engineering Company. Phone: 1-888 853 9963
    Website: www.nashjenningspumps.com

    The first step in solving any problem is TO IDENTIFY THE PROBLEM.
  • scottnjr
    scottnjr Member Posts: 60
    Well, I figure since it was brand new, the valve seat should be fine
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,251
    The trap should work but I would calculate the load on it just for fum an over sized trap can wire draw the seat and fail prematurely
  • Pumpguy
    Pumpguy Member Posts: 691
    I agree with @EBEBRATT-Ed. That said, a large orifice will have a large contact area with the valve, equaling more area for leakage. The smaller orifice will have less leakage. This comment is not from conjecture but from actual experience.

    Do all 3 of these H pattern traps have the same nameplate info? If yes, then it is not likely this is the problem.
    Dennis Pataki. Former Service Manager and Heating Pump Product Manager for Nash Engineering Company. Phone: 1-888 853 9963
    Website: www.nashjenningspumps.com

    The first step in solving any problem is TO IDENTIFY THE PROBLEM.
  • JUGHNE
    JUGHNE Member Posts: 11,248
    I only have changed heating traps.......2PSI operation.

    IIRC, there are different ratings for pressure differential.
    I would guess you are above 15 PSI.
  • JUGHNE
    JUGHNE Member Posts: 11,248
    Also if you take out the lower plug and install a test valve there it will tell you about where the steam is right away.
  • JUGHNE
    JUGHNE Member Posts: 11,248
    Also is it possible that steam from the boiler could be coming back to the pump thru a failed check valve. If the pump feed in high on a Hartford Loop that is......?
  • scottnjr
    scottnjr Member Posts: 60
    thanks for all the responses. This trap has a 15 psi limit, and they run at 12psi for hotter steam. I went back and pulled the trap apart thinking that the float maybe was stuck open. I didn't really find definitive evidence of that, but I adjusted the position of the rod in the hinge and reassembled. so far it is no longer spewing live steam.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,251
    @scottnjr

    Since your running close to the maximum pressure it is even more important that the traps be sized correctly.

    You can but 30 psi traps (It's usually the same or similar trap with a smaller oarfice) Traps are sized based on inlet and outlet pressure diff. So if a 15 psi rated trap carries x amount of condensate a 30psi trap of the same pipe size may carry 3/4 x

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