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Heat Loss Help

JimRaffertyJimRafferty Member Posts: 19
Here's the particulars:
Local school had a fire sprinkler system installed.
The exposed mains run up inside an unheated brick stair tower.
15'w x 20'l x 4 stories high. Very loose old construction, no insulation, 2 interior walls, 2 exterior walls, (2) doors to exterior, (4) 12 sq ft single pane windows. Phila zip code.
We have been asked to provide enough heat to protect the pipes from freezing in winter. Maintain 40*?
We recommended insulation to protect the pipes, but any ideas how to calculate a load for this application?


  • Jamie HallJamie Hall Member Posts: 12,937
    Honestly, I'd do it the same way as any other Manual J -- although there are going to be some loosey goosey assumptions in there. You know the wall area and the construction; you can get an R value from that. You have the window and door areas and their R values. I'd assume fairly high infiltration (heck of a stack effect in there!). What I would do is either add a fudge factor to the final number -- or use a higher internal target temperature; say 45 or 50.
    Br. Jamie, osb

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

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • pecmsgpecmsg Member Posts: 1,449
    Ray Chem heat tape and insulation
    Steve MinnichSTEVEusaPA
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 7,079
    If the building is heated you don't have to consider the two interior walls. I would put the heat near the two exterior doors and most of the heat on the lower floors due to the stack effect. I would make sure the doors close tight and are weather stripped.
  • STEVEusaPASTEVEusaPA Member Posts: 4,188
    40° doesn't give you much room for error.
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