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Steam not reaching all convectors

SteamCT
SteamCT Member Posts: 22
I have a two-pipe Steam system with insulated supply pipes and under 5 PSI pressure from the boiler.  I am trying to figure out why steam isn’t reaching all of the convectors.  It is a larger house with some convectors ~60 feet from the boiler.  I realize there are probably lots of reasons, such as bad steam traps, but I’m wondering if I’m missing anything obvious?  

Comments

  • SteamCT
    SteamCT Member Posts: 22
    I know, a very open ended question.  My water level is good, no cycling, no leaks, but not all convectors getting (or holding) steam.  It’s probably a venting/trap issue, as you note, but wondering if anyone would suggest increasing the pressure somewhat, for example.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,512
    Take 3-4 pictures of the boiler and the piping near the boiler and post. Stand back so we can see. Post a couple of pictures of you convectors.

    5psi is too much pressure should be 2 psi max 1.5 is better.

    Is your system 1 pipe or 2 pipe?
  • Jamie Hall
    Jamie Hall Member Posts: 23,272
    If anything, decrease the pressure. If things don't work on 2 psi, there's something else wrong.

    For starters... where is the thermostat and, if it is digital, what cycles per hour setting is it set for and, if it also has settings for type of radiation, what are that set for? A common problem is that the thermostat doesn't allow the boiler to run long enough.

    Second, are all the steam mains insulated? That can make a big difference.

    Third, since this is two pipe steam, are the returns adequately vented? They must be. That's actually more important than main venting (which, on many two pipe systems, is done by crossover traps, not vents, anyway).

    Fourth, go and check the returns. It's OK if they are warm, but not OK if they are really hot. Really hot would mean that at least one trap is failed open -- and just one can kill the heat to a substantial part of the system.

    Fifth, go and check any wet returns. Are they firmly and definitely below the water line for their full length? If not, that's another way that steam can get into the dry returns and kill your heat.

    Sixth, go and check all the traps. They do fail -- particularly if they are run on excess pressure, which yours are (do get that pressure down to where it belongs). They may fail either open or closed; if open, that convector will heat beautifully, but nothing else on that dry return will. If failed closed, that convector will heat very little, if at all.

    Seventh, go and check all the vents. They also will live a short and miserable life on excess pressure, although it is more likely that they will fail open rather than closed (which gives rise to excess water use, which will kill the boiler...).

    Some project for you. Report back what you find, please!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    ethicalpaul
  • SteamCT
    SteamCT Member Posts: 22

  • SteamCT
    SteamCT Member Posts: 22

  • SteamCT
    SteamCT Member Posts: 22

  • SteamCT
    SteamCT Member Posts: 22

  • SteamCT
    SteamCT Member Posts: 22
    Honeywell thermostat in the living room, Pro 4000 Series.  I’m not aware of cycles per hour setting, though will look into it.

    Pipes are freshly insulated.

    Returns are just warm.

    the main vent is pretty new and whistles beautifully.

    Wet returns are below the water line.

    As for return venting, I’m not sure what to look for.

    And with the convectors traps, I’ve replaced the cage units on some of them but more to do (I’m using Barnes & Jones thermostatic trap interiors).

    Thanks
  • JUGHNE
    JUGHNE Member Posts: 11,058
    Show us the pressure control settings with the cover off if not clear plastic.
    Also more shots of your boiler piping from different angles so one can see what pipes are joined wherever.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,512
    The near boiler piping.......not liking it so far
    BobCethicalpaul
  • Jamie Hall
    Jamie Hall Member Posts: 23,272
    Nor am I @EBEBRATT-Ed . Can we have some more pictures -- from at least three sides -- showing how that boiler is piped? All the way up to the overhead?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • archibald tuttle
    archibald tuttle Member Posts: 1,085
    "wondering if anyone would suggest increasing the pressure"

    i'm late to the party but everyone on here will tell you immediately, lower the pressure. that is the magic of steam, it takes almost no pressure to deliver heat as long as the venting is working.

    I service a two pipe steam convector system similar to this (although not with repsect to the boiler or near boiler piping, i concur it might be less than ideal but you can get a way with murder as long as it's not slugging water into the steam mains which, if serious problem, should be obvious by the banging of steam passing through trapped water pockets). Absolutely the first thing you do for any convector not getting steam is pull the trap cover with steam on. If the convector fills directly, your steam trap is the problem. If steam comes from the trap exit instead of filling the convector that would indicate steam trap[s] failed open elsewhere in system.

    Speaking of which, you say the main vent whistles. maybe you do have a closed circuit main vent with steam trap and you hear it, or are the main and return not connected except through the convectors and you have an open to air steam vent at the end of the main?

    I'm not familiar with the brand/operation of the handle-less convector valves on the supply side. If those aren't easy to close you need to be ready to throw the top back on directly if this test is successful at steaming the convector until you have a replacement.