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Hi Again from San Francisco!- Question on Venting

SFbirdSFbird Member Posts: 103
Hello all, You might remember all my epic threads regarding our new boiler and all the ongoing issues we had mainly due to our plumber being not as "with it" as you all are here!

Anyhow, things are going pretty well! We finally found the source of an ongoing steam hammer problem that has been with us since we had an earthquake retrofit done in our garage in 2006. Turns out a main line from the boiler that went horizontal from the header, through the boiler room wall to the garage to the mains and risers had been "reconfigured" by some genius who thought it could go south again for a foot and then back up again a foot later, to more easily go around some of the 2x4's in the wall. So basically we had flat bottom "U" trap with water sitting in it that was waking up the owner in the unit above that area every morning at 5:30 when the boiler came on.

Anyhow, in the process of reconfiguring that pipe, I am afraid my plumber took all my talk of "more venting" to heart and he put a vent right on top of the pipe from the boiler. See the photos below. The old pipe that is no longer connected is still hanging from the ceiling right above the vent so don't let that confuse you. Just please tell me if this is just totally useless, dangerous, or harmless. I don't see any purpose in having a vent this close to the header but I am not a plumber. From all the great diagrams on venting that Rod has sent me through this forum, this does not seem familiar to me and I need to know if I should have my guy remove it before he goes back to insulate the new pipes. Thanks!


  • SFbirdSFbird Member Posts: 103
    small photo is sideways

    Sorry! Don't know why my computer does that to me. Pic is the same vent from different angle. First picture shows accurate orientation.
  • MTCMTC Member Posts: 181
    that vent is useless.

    it will vent for about the first second of producing steam, then slam shut and serve no purpose.

    is it unsafe? no, not particularly. the only real danger is that this vent will probably take a lot of abuse in this location, and fail quickly. that may allow steam/water to come out the vent, making the system less efficient, and possibly dripping on electronics below or something and causing damage.

    it should be taken out and plugged.

    i haven't read your previous posts (I don't think). Do you have 1 or 2 pipe steam? Is there a good place after the last riser to a radiator on the steam main(s) to add venting? That's where you want it to be, ideally. Or it can also go on the return pipe similar to where it is on that supply line, for easier access.
    backwords flue

    Not sure if I am seeing it correctly but is the flue pipe backwards(meaning male/ridged part of flue pipe toward boiler)? If yes then you have yourself a rather dangerous situation on your hands. Again pic is a bit blurry so I might not be seeing it right.
  • SFbirdSFbird Member Posts: 103
    not sure.....

    The first photo is oriented correctly, second is not( sideways flip).

    I am adding another one that was taken before that steam pipe was shortened and the vent was added. The flue is the big aluminum pipe right? Our hot water heater is vented into the same flue as the boiler, you will see that part of it coming in front...then they join and go out through the wall to the chimney. I can take a close up tomorrow of the connection if you think it is problematic.

    And to answer that other question, we have one pipe steam. I will see if I can dig up the old threads if you are interested......drama and more drama!
  • SFbirdSFbird Member Posts: 103
    Old Threads, Second One VERY long

    Just for background if you have an hour to kill. Very long and drawn out but let's just say this forum has saved our condo association a lot of pain so far. 1st link is most recent.
  • Paul48Paul48 Member Posts: 4,253
    Hey Bird!

    How's the building heating now? Any problem areas?
  • MTCMTC Member Posts: 181
    I can't see the flue vent enough to tell,

    but if bn is right, its a good catch!

    Maria, the flue is the aluminum pipe coming out the top of the boiler. It takes the exhaust gas away from the boiler to the outside.

    Now think like you're hot air moving very quickly through that pipe. You want every fitting in the pipe to fit inside the next one in the direction of air flow, so that it guides you inside the next pipe. If the fitting is the other way where the pipe closer to the boiler goes around the outside of the next pipe down the line, there will be a lip there that is oh so tempting to you, as hot air, to try to squeeze through to the much cooler area outside the pipe. Hot always moves to cold.
  • SFbirdSFbird Member Posts: 103
    Hi Paul!

    The building has been heating well. Now that I solved that long festering steam hammer issue I actually was rewarded with a bottle of wine from the owner of the unit that was being disturbed every time the boiler came on! We are still working on getting the TRV's and boiler controls installed before the weather gets warmer ( if you can call SF warm, ever). Our "original installer" made off with my copy of Dan's book ( Pocket Full of Steam Problems) but judging from that vent he just put in, he wasn't reading it too closely.

    Now I have to be sure that flue isn't going to kill someone......
  • SFbirdSFbird Member Posts: 103
    I'll check it out

    I'll get better pictures in the morning and see if I can figure out what is happening down there with that flue. I wasn't really ever impressed with the whole configuration but I'm hoping that the installer wasn't totally clueless.....

    The boiler room itself is really well ventilated,;there is a window that pretty much has two 7x5 ( at least) panes missing so there is air moving through there all the time. But obviously if the thing is set up the wrong way I would want to get it fixed right away.
  • RJRJ Member Posts: 484

    Check the horizontal pitch on the flue pipe.   Do you work around Pacific Heights lots of intersting old steam systems in that area.
  • RJRJ Member Posts: 484

    This is not the first picture i have seen on the wall where the installer has used a vent tee for the steam vent.  I had problems on a couple of bldg's with this install in one case i replaced a leaking vent only to find it leaking  2 wks later.  I gave the customer a quote to repipe with a tee on the horiz. run   see page 115 lost art of steam
  • PumpguyPumpguy Member Posts: 274
    The usual

     arrangement used when piping steam mains or condensate returns around obstructions is called a DOOR LOOP.  This is illustrated in the lower left corner of page 95 in The Lost Art book.  Other solutions to this problem are also discussed. 

    This being a one pipe system, the boiler side of the steam main should connect to the door loop at a minimum 1" lower than the system side. 

    A condensate pump can be used as a mechanical lift in extreme situations, but with a one pipe system, you would want to avoid using a pump if you can. 

    If you don't have The Lost Art book, just Google DOOR LOOP PRINCIPLES, and you'll find illustrations and discussion of how it works.
    Specializing in vacuum pumps for steam heating systems, especially older Nash Jennings units. We build new ones too!

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  • SFbirdSFbird Member Posts: 103
    edited February 2013
    More Photos of Flue Vent Pipes

    Hope these are more helpful. I can't tell what is going in the right direction or not, I'm just a homeowner not a plumber!

    Just FYI, that thinner vent pipe running across the room in picture 2, going into wall on right is a clothes dryer vent pipe that goes out the window that is just out of view on left. Boiler and heater venting goes through wall in pi. 2, takes a slight turn on other side into chimney.
  • MTCMTC Member Posts: 181
    In those shots

    Everything looks ok to me, that I can actually see. There are a couple that are hard to tell b/c they've taped them and such, but the ones I can see look proper.
  • SFbirdSFbird Member Posts: 103

    That makes me feel better, thanks! When we get our guy out here to work on installing the TRV's and boiler/thermostatic controls I will have him inspect the flue ( he is a different contractor, not "original installer").
  • SFbirdSFbird Member Posts: 103
    Not a Plumber...

    myself, so I don't see many other systems. This replacement in our building has forced me into a quick steam "education". Thankfully, I found this website!
  • RJRJ Member Posts: 484

    Your latest post  now shows 2 boilers, i didnt see the other boiler before when i remarked about the flue pitch. I would still check the peerless boilers and Tele. Larrs recommended flue sizes, alot of times the flue needs to be larger than the flue collar connector on the boiler depending on the commom flue height.
  • SFbirdSFbird Member Posts: 103
    Hot Water Heater

    The smaller unit in the wider shot of the boiler room is the hot water heater, don't know if that makes a difference as to flue pipe sizing requirements?
  • RJRJ Member Posts: 484

    I forgot,    the flue seems to reduce when going through the wall,  what are the btu ratings of both boilers and what are the dimensions of your chimney.
  • RJRJ Member Posts: 484

    Most deffnetly makes a difference in the common flue size
  • SFbirdSFbird Member Posts: 103
    Steam Boiler is 399 BTU

    Need to check on the water heater, will post in a bit.
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