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hydronic separator

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Snowmelt
Snowmelt Member Posts: 1,415
in THE MAIN WALL
i ave a 80,000 BTU cast iron boiler with 2 - 007 pump, there is existing 2 baseboard zone roughly 30,000 each . I want to add a 1" NPT Hydro Separator (found at the shop laying in the box) and add a 3rd zone for possible radiant floor. the radiant is a small kitchen 1 loop roughly 6,000 to 7,500 BTU's. will the hydro separator over come the return temp of the radiant floor so no condensation goes in the chimney?

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  • hot_rod
    hot_rod Member Posts: 22,143
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    Nope. In the simplest form a separator is just a jumbo sized closely spaced tee assembly.

    However that is a fairly small load for a 80K boiler and should not offer too much of a low temperature return issue when it alone is running.

    Is the 80K input? If so, at 83% efficiency you have a 66K output. Two 30K and one 6K is right at the boiler max. output.

    You will need a mix down device for the radiant zone.

    You could crunch some numbers and see what that low temperature return would do to the boiler when all zones, high and low temperature are running. Plug flow rates and know temperatures into the mixed temperature formula.

    Consider UltraFin and run it at the same temperature as the fin tube zones. Then all the concerns are addressed, no mix valve required, no issues with return temperature, no hydrosep needed.

    You will experience short cycles if and when just the 6K load calls, on a one speed boiler :)

    The 007's seem large for 3 gpm zone requirements? If they are multiple speed, run them at low setting.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Snowmelt
    Snowmelt Member Posts: 1,415
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    thanks hot rod, that was my second plan, my first is use a small indirect, ( other post) use it for the radiant floor side. I have until beginning of October to do this.
  • hot_rod
    hot_rod Member Posts: 22,143
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    As others mentioned, it seems the indirect tank, while a great solution, will be fairly $$.

    if the application allows the UltraFin is ideal for a small floor warming.

    There are some simple ways to add a mixed zone to the fin tube zone, but it would require running one of the fin tube zones to have the radiant zone. Some examples here.

    https://www.pmmag.com/articles/84495-a-little-floor-warming-please-john-siegenthaler
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Snowmelt
    Snowmelt Member Posts: 1,415
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    I already have plates from viega from another job so I am just going to tack them up with zip screws. i have 1/2 inch heating pex also. i am just going to buy a 3 zone board and i already have the pumps in my work truck. I think i will just buy a small 30 gallon indirect and go with that. but I appreciate all the help you and the heating help crowd gave me on this one.
  • hot_rod
    hot_rod Member Posts: 22,143
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    Remembering also, the "dangled tube" (suspended tube) method was promoted as a floor warming, high operating temperature system.

    Uponor Appendix E Joist Heating- No Plates has output graphs for that installation method. If the load is low in relation to the square footage you have available.. it's an option.

    I suppose putting plates on suspended tube sort of builds a UF system. If you are looking for simple and inexpensive.

    Once you attach plates you need to supply lower temperature to them.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream

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