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Zoning a Steam System in an old school?

As I get ready to install a new steam boiler, is it generally a good or bad idea to zone the 1930's school? Is it cost effective? Will I create more problems?


  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    Zoning is generally a good thing

    but as with anything it must be done properly.

    You'd need to tell us a bit more about the system. Does it use cast-iron radiators in the rooms? If so, are there two pipes connected to each radiator or just one?

    If you can post some digital pics here of the boiler room and some radiators, that would help.

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  • ttekushan_3
    ttekushan_3 Member Posts: 958

    Hello, Br. What kind of boiler is to be installed? I strongly, STRONGLY recommend a boiler that is able to vary its flame level. A single firing level with zone controls (which vary the demand on the boiler) is asking for trouble. A boiler with as few as two output levels, i.e., full flame and "low" will make it feasible. You may see this as referred to as "turn-down ratio."

    On to the zoning. I don't recommend disturbing the main steam lines for the purposes of zoning for several reasons. Disturbing those lines will cause trouble. Installation of zone valves in steam mains is tricky business, and if the smallest detail is overlooked, you will wind up with water hammer that even the Good Lord will notice. Finally the existing steam main routing may be inconsistent with the heating needs in the rooms above.

    The only zoning via steam main valves, would be if you really only need one zone control, say for the church when rectory or school remain heated fully. More details would be nice.

    The easiest, cheapest and most effective would be zone control valves on the radiators themselves. Zone valves for radiators are available in electric models so room thermostats can be used. In the old days, we would use an elaborate pneumatically (air pressure) operated room thermostat system. Today, electrical operation is desired.

    Danfoss, and Honeywell and others make such valve/thermostat systems.

  • John White
    John White Member Posts: 120

    I would recommend reviewing Non Electric Therm. Rad Valves.
    Honeywell or Danfoss (and about 500 other companies!) make very good ones. when I was in the rep business I did a number of schools in the Carolinas this way. All very succesful. Just a thought. jw
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