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Steam boiler with hot water coil control

A steam boiler is used for both heating and DHW production. The boiler is controlled with Entech Boiler controller. Aquastat set to 180F, the boiler cycles half an hour. During off-cycle, the mixed domestic hot water temperature drops from 135F to 110F. Is there a way to solve this high water temperature range without the installation of a motorized mixing valve?


  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    I presume the mixing valve has a fixed setting? Substitute one which is thermostatic. Both Caleffi and Watts make them.

    And if the boiler isn't firing to maintain at least 140, fix the aquastat while you're at it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Murat
    Murat Member Posts: 2
    Thanks, Jamie. The thermostatic mixing valve seems like the best option.