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Boiler Water Temp

as we typically define it, is a function of running water through the boiler that is below the flue gas dewpoint, <i>while the burner is firing</i>.

If the burner is off and the system goes cold (to ambient temperature), any rust you have is just a function of too much humidity. Much less of a concern than condensation of corrosive flue gasses within the boiler.


  • JM_9
    JM_9 Member Posts: 5
    Boiler Water Temp & Condensation

    I have a 12+ year old Slant fin w/Beckett and indirect water heater which I installed. Live in NE. The indirect Boiler Mate has some build up on the inner coil and calls for heat more frequently. To further save precious oil, I put a timer on the indirect control to the Aquastat so that the boiler will only kick on in the early AM & PM during the warm summer months as the thermostats are off. The boiler mate does a good job of keeping the water hot during the day (we both work). My concern- the boiler is off most of the day/evening and as it cools down do I need to be concerned about condensation/rust buildup? Boiler temp is set at 170. basement has dehumidifer so basement dampness is not an issue.
  • JM_9
    JM_9 Member Posts: 5

    Brad, Thank you for your prompt reply. I have read other articles that warn about too low a boiler water temp that can cause condensation and potential rust problems with the cast iron sections. This is a typical baseboard hot water setup w/indirect water heater that is programmed on in AM and PM (1 hr each- enought to bring the hot water up to temp) to so the boiler is off much of the day. The boiler temp gage goes down below 100 F
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