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mega steam mst396 or mst 513

Replacing peerless jot 150 4 section boiler with burnham mega steam added up my edr of rads EDR comes out to 370 times 1.33 pick up factor gives me a DOE rating of 118,000. my steam main is fully insulated with fiberglass If I use the 1.5 pickup factor because I use a setback thermostat at night and when I am not home I also have a 10 ft run through a a cold crawlspace. My DOE rating is 133.000  the mst 396 rating is 127.000 and the mst513 rating is 164.000 I also plan to add a heating loop in the basement at some point.I seem to be in the middle of these two models.My current peerless jot150 has a beckett burner with a firing rate of 1.00gph and heats really well I am seeking the efficiency of the 3pass system to utilize more flue gas heat what do you guys think any help is greatly appreciated


  • SWEI
    SWEI Member Posts: 7,356
    SImple route

    370 feet of EDR.  MST396 has 396 sq feet.  Done.
  • ChrisJ
    ChrisJ Member Posts: 15,462
    Just a homeowner

    Don't increase your pickup to 50% just because you do a setback.  The 33% pickup factor already includes this and in my opinion is too much.  I feel a 10-15% increase is enough especially with insulated mains and piping just as long as you calculated your radiation accurately. 

    How well is your radiation matched to the heatloss of the building?  if its oversized, which most are this is even more reason to cut down on the pickup factor.  The radiation being oversized is enough on its own to increase temperature after a setback.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • charlie_22
    charlie_22 Member Posts: 18
    mega steam mst396 or mst513

    Thanks youre probably right