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Which size to choose?

felixm Member Posts: 3
First off, let me give a big thanks to this forum for helping me out years ago to explain to an installer what a Hartford loop was. Much thanks!

I am deciding between the Burnham MST288 and the Burnham MST396 for my steam system with 325 sq. ft. of radiator to replace the Weil McLain 86 rated for 355 sq. ft. The 288 is under-sized by @ 12%, and the 396 over-sized by @ 23%. What factors should I consider? Already one contractor is leaning one way, and one the other way.


  • northernboiler
    northernboiler Member Posts: 55
    The MST396 only

    i would also recommend installing it using a drop header. As per the manufacturers specs. The only thing I would do, if possible to augment Burnham's specs as to the near boiler piping is this:

    1. The 2 risers exiting the boiler, get them as high up as possible. not just the 24" to the bottom of the swing joint.

    2. The main boiler header. I would increase the size to 2 1/2" to 3"

    (This piping will assist with slowing down the steam & help in keeping it as dry as possible.)

    3. The hartford loop pipe at 1 1/2"

    4. The return line. I would not use any size less than 1 1/2"

    5. Make sure your installer uses an automatic water feeder with a manual bypass.

    (I recommend a VXT-120 because it has the meter display)

    6. Make sure the installer use black pipe and Cast iron fittings (CI) for the piping- NOT COPPER

    (I really shouldn't have to say this, but given how many steamers we re-install every year, because some people either do not how to do it properly or want to take a short cut, for time purposes, I mention it.)

    7. Have the system completely flushed before installing the new unit.

    (We do, and I must tell you, around here, almost no one else does it. Let alone even knows it needs to be done. It may cost a little extra labor but the benefits far out way the cost)

    8. Main vents ok? As a matter of course, we replace the main vents on every install. (when equipped) Some would argue, that it isn't always necessary, however, when a client is already spending thousands, why not. It's not going to hurt.

    Remember, it is the details of the job and the extra little things, like i wrote that will make the install go better and the system perform correctly and most importantly, efficient. saving you $$ in the long run.

    btw- where are you located?

    And good luck, the MST is a fine unit, works very well, when installed properly
  • felixm
    felixm Member Posts: 3
    Reply to northernboiler

    Lancaster County, PA, @ 10 miles from the Burnham plant. A co. who goes there for training is taking a look in a few days. Thanks for the advice.
  • vaporvac
    vaporvac Member Posts: 1,520
    Great tips...

    These are great tips for a new instal. Could you share how to flush out a system? I'm a homeowner of a two-pip Trane Vaporvacuum system that will soon be getting new boilers. I'd like to do this myself to ensure it gets done.and hadn't considered this  before.I will be re-piping the wet return.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • Steamhead
    Steamhead Member Posts: 16,732
    MegaSteam with drop header

    here's one example.........

    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
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