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    Boiler system return flow problem - circ location? (4 Posts)

  • jb jb @ 7:41 AM
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    Boiler system return flow problem - circ location?


    I've got a bit of a jerry-rigged piped boiler system in an old house in Virginia.  The boiler was replaced in 2004 - with a new Weil McLaine boiler - but the piping system is from the 1920's I think.

    It's one zone supply and return pipe CI radiator system.  It appears some larger pipe on the return side was cut
    out and down sized as a result of a leak during the boiler changeout and a circulator was added
    to a return from the kitchen rad to increase flow to/from this radiator?  This added circ.
    pumps towards a Tee that brings in a return from a far flung piping branch (upper rear BR) that
    is not getting good heat flow.  Is this circ on the wrong side of this
    tee?  What happens when you pump at a Tee like that that should be returning flow from another branch?  The larger return pipes further from the Tee to the right seem to
    flow fine and perhaps due to pipe size seem to flow/heat well as compared to the smaller piped branches. 

    Should I relocate that circulator/the branch that it pumps towards - so that branch comes in on the suction side of the circ - and the circ will 'pull' both of those return branches?   If it's a certain number of diameters from the larger return coming in - does that insure it doesn't interfere?

    See attached photo.  All pipes shown are returns.  The other/main circ on
    the system is on the supply right as it leaves the boiler pumping out of the boiler - but it does pump towards the expansion tank/air eliminator (which I need to change so it 'pumps
    away' right?).  I'll raise/show that one in another post to see what you guys think.

    any thoughts would be appreciated.

  • Mark Eatherton Mark Eatherton @ 8:29 AM
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    Time for some good ol' SawZall Surgery....

    Cut all that crap out and put it in right, cause once you touch it, you own it, and anytime there is a problem, it becomes YOUR problem, not the previous installers.With gravity conversions, it is acceptable to decrease pipe size, by 1/2 the original, then drop one more pipe size. So for 2" gravity main, connecting with 3/4" is perfectly acceptable.Put balance cocks on all the returns to adjust flow to the individual radiators. THere is also a good chance that there are orificies in the upper radiators that are going to mess with your balancing program.And by all means, definitely set it up to pump away from the expansion tank and air separator and boiler.You will have to bottom fill, and top vent the system. It can not be power purged.Mark all lines before you start surgery, and do a good job of cleaning up that mess :-)Post photos when you are done.ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
    This post was edited by an admin on October 30, 2009 8:31 AM.
  • Jamie Hall Jamie Hall @ 8:50 AM
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    Whoever invented

    the SawZall was a genius...

    But to answer the specific question, yes that circulator is on the wrong side of the T, and yes it will kill any circulation there might have been in that far flung branch...

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • jb jb @ 9:00 AM
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    Thanks Gents.

    I was afraid of the 'cut out all the mess' prescription - but I know that's right.  It's my rental property and there is heat flowing (just not optimally) - so I will try to limp it along through this heating season - and then scrub in for "sawzall-ectomy" in the spring.  

    Appreciate the advice and expertise.
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