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Condensate in a Standard Tract House Atmospheric Boiler Installation During Fall Weather

allthumbs Member Posts: 6
I have read discussions pro-to-pro regarding condensate with low return temps. I couldn't find the answer I need. I use my atmospheric hydronic boiler during the fall. It quickly satisfies the thermostat, and the return temp is always less than l30 degrees at shutdown. In the winter, the return temp. is always above 130 at shutdown. The boiler is a 35 year old Utica. Should I avoid heating the house during the Fall?


    EBEBRATT-Ed Member Posts: 9,678
    edited October 3
    If your boiler is 35 years old and you have no damage signs from the condensate so far then your probably ok

    It's normal for the return water to be below 130 on initial start up but you don't want to run the boiler continuously or for long periods of time with 130 deg or colder return water.

    If you were getting condensate damage you would usually see:

    Deterioration of flue pipe
    Rust stains on the boiler jacket or running down the boiler jacket, especially around the flue pipe.

    And you would usually see white deposits around from the calcium in the flue gas condensation

    If you post a few pictures we could take a look
  • Jamie Hall
    Jamie Hall Member Posts: 16,591
    Pictures are always good... one might ask, though, what are the output temperatures? And what kind of flow rate is being used? It might be possible to tweak either the flow or the output temperatures -- or both -- to get the return temperatures to come up.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • dopey27177
    dopey27177 Member Posts: 717
    If this a water heating system I would raise the aquastat temp to 190 with a 20 degree differentialto try to get the return temperature ti 140 degrees.

  • STEVEusaPA
    STEVEusaPA Member Posts: 5,187
    Down the road, when it's time to replace, make sure they pipe it for boiler protection, unless it's a Mod/Con.
  • hot_rod
    hot_rod Member Posts: 14,868
    Gas or oil? Metal vent pipe or masonry chimney?
    Ideally the boiler should be operating out of condensing temperatures within a 10 minute run time. 10 minutes or more run time is preferred to get to steady state efficiency, dry out the flue, etc.

    Watching the entire run cycle on a mild heating season day would show you if it is "dripping" condensing, insides. Making sure the flue piping warms sufficiently can be a bit tricker.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • mattmia2
    mattmia2 Member Posts: 3,668
    Increase the anticipator on the t-stat to make it run longer cycles?

    Maybe the heat that is still in the boiler from the last cycle is enough to satisfy the t-stat. Maybe use a 2 stage t-stat, first stage runs the ciruclator, if it doesn't satisfy after 5 or 10 minutes, second stage fires the burner.