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Reducing gas supply to oversized steam boiler????

Steve Nichols
Steve Nichols Member Posts: 124
Hi all,

I just jumped over from the steam section at the suggestion of Crash2009. He's been helping me out on my newest adventure.

I replaced my original (old) steam boiler with a new Burnham 5SIN steam atmospheric boiler.  It turns out that the contractor incorrectly calc'd the boiler size and this thing heats stuff up in a hurry.  Main issue here is short cycling (shutting off on Pressuretrol).  I can only get about 2 minutes run time before it shuts off, drops pressure and then refires (repeat and repeat and repeat....)

The Burnham rep is coming out on Tuesday with the contractor.   I have no clue what may happen.  Ideally, I'd like to exchange for a 4 section as that would fit much better with my connected load.

I've heard a lot of options out on the message boards (swapping out boiler, removing a section and replacing with proper burner assembly, and plugging orifice in existing burner..also something about CGA's)

So, can anything be done to decrease the "fire" to the boiler so that it still functions efficiently but at a reduced BTU?  Right now I'm about 30% oversized.

I like to hedge my bets and understand what options could possibly be tossed my way with regards to manipulation of the input gas.   In case the rep. tosses the responsiblity back on the contractor, I think I should be informed as to what is an appropriate course of action that still leaves me with a functioning and efficient steam boiler.

I have no knowlege in gas heating so any assistance you can provide would be great.
striving for peaceful coexistence with an oversized boiler....


  • JStar
    JStar Member Posts: 2,752

    Lowering, or derating, a gas appliance is both innefficient and unsafe. That method is largely regarded as a terrible idea. The contractor has a responsibility to correctly size and install the boiler.
  • Steve Nichols
    Steve Nichols Member Posts: 124
    Cross that one off my list!

    Thanks JStar, that makes it easy for me.  No modifications to the gas system!  Man this thing heats water fast!
    striving for peaceful coexistence with an oversized boiler....
  • crash2009
    crash2009 Member Posts: 1,484
    We were discussing

     that subject over in steam as a possible "bad idea"  Thanks for confirming.

  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    It is a good thing the

    rep is coming to look at the boiler. He will be able to tell you what the options are. As has already been stated here reducing input on a design gas boiler is never a good idea as it can reduce boiler efficiency which in turn reduces overall efficiency.

    Something else to think about is adding some radiation to some areas that may be cold in the house. Such as entry hall ways, work shops in the basement etc this will help with the short cycling.
  • Steve Nichols
    Steve Nichols Member Posts: 124
    But wait...

    Thanks Tim,

    It turns out that the Burnham rep is coming out b/c I questioned the use of an undersized equalizer pipe in the install.  He has no idea about my concern regarding the short cycling issue. 

    As for adding additional radition load, that is what I was thinking about, but this thing is soooo overisized that I would need a lot of cast iron radiators to use up that available heating input.  Just for informational purposes, with adequate main venting and a properly set pressuretrol and a reasonably stable water line,  the boiler only runs for 2 minutes before shutting off on high pressure, time and time again until Tstat is satisfied.
    striving for peaceful coexistence with an oversized boiler....
  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    edited October 2012
    The rep should be able

    to answer any of your concerns. What size is the header on this setup and what size is the equalizer?

    As for the contractor oversizing that is on him and he should amke good by replacing the boiler with one sized correctly. Next time he will be more careful and do a heat loss and measure the square feet of EDR (radiation).

    What is your location in the country?
  • Steve Nichols
    Steve Nichols Member Posts: 124
    edited October 2012
    Here's hoping

    that the contractor will make good.  We just had a phone conversation and he said that he gave my EDR numbers to his engineer and he came up with a 5 section.  I don't think he read my sheet correctly as I included both bare sq ft. of steam and one that is 33% larger for the pickup factor. 

    No need to get into all the particulars of the conversation except to say I am worried that he will try to downfire the boiler or something like that to get out of it.  JStar has already weighed in and altering gas supply will NOT be an option on the table.  I think the Burnham rep will agree that that is not a reasonable solution.

    But with the rep. being a "third party" does s/he really have any pull with a contractor in the end? 

    Header size is 2", current equalizer is 1.25".  EDR is 256sq ft of thin tube convectors.

    I'm located a bit north of Boston, MA.

    Thanks again, Tim.
    striving for peaceful coexistence with an oversized boiler....
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