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Can I bypass this ventless radiator in the basement?

david_and_heather Member Posts: 28
edited May 2021 in Strictly Steam
There is a very strange radiator in my basement. The upper right of the radiator connects to a supply. Just inside the wall, the lower left rejoins the dry return below the radiator. There is no vent. There is no valve. The radiator rarely gets more than a little bit warm. It is a one-pipe system.

My question is: can I safely have this radiator removed from the system entirely? If so, can I simply cap the pipes at the upper left and lower right, or should I still have a pipe that connects them? If I need to connect them, does it need to cut diagonally across the opening, or can it make a right angle? I'd love to reclaim this precious wall space for a mini-split and/or a HRV.


  • Jamie Hall
    Jamie Hall Member Posts: 23,324
    I honestly have no idea why that might be there -- but there are things in Cedric's home which baffle me as well.

    On cutting it out. That depends on what it is doing (or not doing) rather than why it is there at all. There are three things it might be doing: helping to vent the steam main which feeds it; helping (oddly) to vent the dry return into which it connects; and providing some heat to the space. There is also a chance that it actually also serves as a drip of sorts for the steam main.

    So... it's not providing much heat, and you don't need the heat anyway. So much for that one.

    Now. Venting. If the steam main to which it connects is adequately vented, while it may be vaguely usedful for that it would seem it isn't required. Had this been a situation where the main was not vented, but the dry return was, then it would have been needed -- and the condensing capacity would have made moderately certain that steam would not get into the return and mess things up. So this option must be considered, but, as I say, if the main is otherwise adequately vented, can probably be discounted.

    On the other hand, there is the question of the return -- and there one has to ask how that return is vented. If it is a true dry return (oh dear, here we go again!) -- that is, separated from the steam mains by a trap and possibly a water seal, and accepting air released from radiators -- then the return does need to be vented somehow (usually with a vent or cluster of vents at the boiler). On the other hand, if the return is simply an extension of a steam main, then it is not surprising it doesn't heat -- more or less equal pressure on both sides -- and isn't needed for venting, as the steam main vents do that.

    I think on the whole the possibility of its serving as a combination drip and vent for the steam main is actually pretty good, particularly if that dry return is a true dry return.

    I would really have to look at how the rest of the system involving that main and return is piped to be sure, but on the whole I would think that if there is adequate venting for those pipes, and if there is a definite way for condensate in the steam main to make its way back to the boiler somewhere else, it could probably be simply capped at both inlet and outlet and filed under "hmm... I wonder what that really was for?".
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JUGHNE Member Posts: 11,062
    Do you know where the 2 pipes are connected into the system?
    Is the inlet the end of the steam main?
    Where is the air venting for the system.
    Is the lower pipe truly a dry return?
  • david_and_heather
    david_and_heather Member Posts: 28
    Thanks, all. I don’t know if the return is a “true” dry return but I can find out if you can tell me how to investigate. It’s definitely above the waterline. The inlet branches off fairly early from a steam main that goes on to feed much of the first floor. It’s actually the first radiator fed by this main, if I recall correctly. There is a vent on this main. The vent is downstream of the radiator.

    We have never seen the entire piping system because part of it is in the wall., including a piece that is sandwiched between brickwork and a beam where there had been an extension built 80 years ago. When we had the ceiling open, though, we saw the connection from the main to the inlet, and we can see where the radiator joins the return below on the left, just inside the wall.
  • motoguy128
    motoguy128 Member Posts: 393
    Let sleeping dogs lie. IF it isn’t causing a problem. Making a change could potentially cause a big headache. A little heat in the basement isn’t a bad thing. I find that Much of it becomes radiant floor heat for the 1st floor since there usually is no ceiling in a basement, so 80F+ air above the joists make for a slightly warmer floor above.

    The kitchen floor is so well heated above my boiler room I’ve debated if I could remove that radiator at some point as I consider renovations. Maybe add a couple small sections of steel fin tube off the dry return and drip them back to the boiler return if needed.
    JUGHNE Member Posts: 11,062
    Is there a recess in the wall behind that rad?
    Are there any unions close to the rad? I don't see any.
    At the end of the steam main where the air vent is located, is there a return line connected on the end of the main?

    Was the inlet to this connected to the bottom of the main?
    If so and there is no end of main return, this section of main could have been counter flow and the rad is the drip for returning condensate.
  • Fred
    Fred Member Posts: 8,542
    If the return is above the boiler water line, it is a dry return. It almost looks, to me like a two pipe radiator on what is otherwise a one pipe system. Are you sure there are no valves or traps behind that wood framing? How far does that left (lower pipe) go before it drops below the water line?
  • david_and_heather
    david_and_heather Member Posts: 28
    @JUGHNE the wall behind the radiator is the brick foundation of the house. @Fred definitely not sure--never seen behind these walls. Sounds like there are a lot of unanswered questions that would need clarification before I messed with this radiator. And since I'm not sure I'm going to like what I see if I peel off these wood panel walls, I suspect those questions will remain unanswered. :-/ Oh well; thanks for your help!
  • clammy
    clammy Member Posts: 3,112
    I ve run into a few exactly like you have . We have always just left them . Some where on single and even a few trane 2 pipe systems w a rad on the end of the supply main pretty much as you have . Of course they where the last to get heat . As other have stated let a laying dog sleep if it ain’t broken or leaking leave it be unless you want to pay some one to remove and repipe Which I doubt will be free ,let it be unless it’s causing issues like banging . Peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • mattmia2
    mattmia2 Member Posts: 9,669
    edited January 2021
    Do those pieces of wood along the bottom look like they were always there? What is above it, does it look like there is a hole for a vent patched in the wall or floor? Double you have the cover that was over it, maybe that was open at the bottom. Maybe it was an indirect radiator.

    Also, think about where the water line was on the original coal boiler, usually they were much higher than on a modern boiler.