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Old system, big problems

Meterman Member Posts: 2
Hi guys: I have an old steam system I want to describe to you. Steam boiler changed back in 2005. The system has had problems for years before the replacement and after. In the boiler room is a Hoffman Differential Loop. Techs previous to our company have totally removed all steam trap inner components and ran the system as high as 7 psi to compensate. The current steam control is a standard Honeywell Pressurtrol set at 1/2 pound with a differential of 1.5 psi. The auto-feeder is over feeding the system. The returns have steam pressure in them and the boiler goes into a vacuum to the point that draining the boiler is a project in it's self. If I am reading the "Deadman Books" properly, I have a true vapor system and should have a Vaporstat controlling, and all of the traps re-instated. Please let me know if I am on the right track here. I have only worked on one other vapor system in thirty-plus years and would welcome anyone's input. Thanks a lot, Meterman


  • Jamie Hall
    Jamie Hall Member Posts: 18,953
    Yes indeed. If there is a Hoffman Differential Loop you have a Hoffman equipped vapour system. Or you did. From what you are describing, you now have a catastrophe...

    First, I hope the Loop is still there, and is properly connected to the system. That is, all the dry returns are connected together and connect to the loop, there is a return from the loop down to the boiler, and there is a line from the boiler header to the loop. If not, we go on a slightly different approach...

    Second, all your main vents should be on the dry returns very near where they tie into the Differential Loop. NO vents anywhere else on the system.

    Third, at the ends of the steam mains there should be crossover traps which tie into the corresponding dry returns. Hopefully at least the bodies of the traps are still there. Since some bright child took the guts out of all the traps, you will need to put the guts back in.

    Fourth, the same bright child took the guts out of the radiator traps. They will all need to be put back in.

    Look on the bright side: you will know that all of your traps are new and working...

    Fifth, install a vapourstat to control the boiler, and set it for no more than an 8 ounce cutout with a 4 ounce differential (giving a 4 ounce cutin). Anything higher than that and the system, if it works at all, will work very poorly indeed.

    Now... having done that, sit back and catch your breath. Next is venting. There are debates on how much venting is really needed -- but if you can get this thing rebuilt as outlined above, it is unlikely that you will need more than 2 Gorton #2s at the main vent location. But you will need that.

    Run the system. If you still have overfeeding problems, check for clogged wet returns or, possibly, returns which should be wet but are now dry because the boiler water line is too low. If you have water hammer, check all the mains and dry returns, including all the runouts, for pitch.

    If you have uneven heat, you can control the radiators individually with the inlet valves, assuming that they are still Hoffman or another quality metering valve.

    Come back with more!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Meterman
    Meterman Member Posts: 2
    Thanks Jamie, I appreciate your input. Now I get to try to explain this to the customer. Fifteen years and now this...I hope they will trust us for the fix. Thanks again. It is really great to have professionals to bounce these problems off of. Meterman
  • Jamie Hall
    Jamie Hall Member Posts: 18,953
    Go for it! You get it all done, you will have one of the best performing steam systems ever made!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Don_197
    Don_197 Member Posts: 184
    @Meterman..............you get to be the saviour! Please keep us posted! For what it's worth, there are very few people left that know anything about these systems, and that's not your fault. I currently work for a Fireplace shop that has a full service department (that I have been managing since last June) There are only 5 or 6 technicians left in our Metro area (almost a half million population) that specialize in Fireplaces/Inserts/Pelletstoves/Woodstoves, because most all the other shops gave up on running in home service, leaving all the work to those 5 or 6, unless people take the risk of having their normal hvac techs work on their hearth products (not usually a good idea). I take calls every day from frustrated people who can't believe how busy we are, or how much we charge for our service. Many of these people try to hang up to call someone else and I beg them not to.............because I KNOW that they will either end up calling me back, or end up paying much more for having "non hearth specialists" work on their hearth products. We have to do the best with what we are left with. Steam is MUCH more specialized, so don't let em be too hard on you (and know that you are the one to take care of them, as long as you care to use this forum and Dan's books to help you)! Now go save that beautiful old system!