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Prog. Tstat on steam


On of our offices has an oil fired Weil McLain boiler that has two zones of baseboard heat and the second floor is steam.  The two 1st floor zones have programmable thermostats and the steam zone used to have an old pin type programmable thermostat.  That thermostat is no longer there and they have been told that a digital, programmable thermostat will not work on the steam zone.  Is this true or are there models/types of digital programmable thermostats that will work?


Bill Lafley


  • nicholas bonham-carter
    thermostat for steam

    the honeywell vision-pro thermostat is rated for steam, and has the advantage that it can have a remote sensor.

    i suspect with a hot-water zone, that maybe a more sophisticated control from tekmar, with an outdoor sensor might do a better job of running the whole system, rather than having several different controls, operating independently. for instance, it might be better to run the hot water circulator at the end of the steaming cycle.

    if you could post a layout drawing here, it might be easier for all to see your situation more clearly, and comment/suggest.--nbc
  • nicholas bonham-carter
    further off wall communication on this

    i received an off wall query about this, and replied; but am copying it here. the poster is seemingly very interested in energy efficiency!a layout plan with the btu's for each hot water zone and the radiator sizes of the steam, would be needed for the experts to give their opinion. just post it on your original thread. in the meantime the honeywell visionpro is certainly steam certified. don't use much setback though as the energy used for recovery from a few hours of setback can equal the savings. best to keep the same temp constatly, and if you can get the system as comfortable as when first installed, that temperature could be lower than 68 deg. have you found a good steam/hydronics man? you can use "find a professional" on the site-where are you? i will add this reply to the thread.--nbc

    -----Original Message-----

    From: HeatingHelp.com

    To: nicholasbc@aol.com

    Sent: Tue, Nov 30, 2010 8:29 am

    Subject: Someone from The Wall has sent you a message.

    Name: Bill Lafley

    E-mail Address: blafley@cetonline.org

    Phone Number: 413-695-2730

    Company: Center for Ecological Technology


    Problem I have is I work in a different office where the boiler is located and I

    don't get out there often (over an hour away). What information do you need?


  • Jamie Hall
    Jamie Hall Member Posts: 23,433
    What an ideal application

    for a computer controlled or programmable logic controlled system!  I like NBC's idea of running the circulator at the end of the steam cycle -- but I would refine it: run it as soon as the pressure goes above a very low set point (use a vapoustat which makes on rise).  That way you will take some of the extra boiler capacity which would otherwise build pressure -- don't need that -- and pump it out into the hydronic side.  Where the computer or PLC would come in is when you need more heat on the hydronic side -- you would want to over ride the vapourstat, and start pulling hot water earlier in the cycle.  Could get a little fiddly, but I can see some real opportunities for optimizing the whole system here...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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