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Stumped

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Tinman
Tinman Member Posts: 2,808
I was in a boiler room today that had a 1.4 MBH steam boiler, piped correctly, short cycling due to inadequate main vents.

Here’s what I don’t get. There was a strap-on aquastat on a vertical return above the water line, wired in series with the pressuretrols.

What is it’s purpose?
Steve Minnich

Comments

  • Danny Scully
    Danny Scully Member Posts: 1,426
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    What was it set to? Is there a tekmar control or a heat timer control somewhere?
  • Tinman
    Tinman Member Posts: 2,808
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    It was set to 200F and there was an R & D Contol.
    Steve Minnich
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,616
    edited February 2019
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    What's and R &D control?
    Have seen aquastats on large steam boilers to keep the burner on lo fire until the boiler gets warm. Obviously not used for that.

    Just a guess. Inadequate venting building not heating well radiation short of steam so they shut burner off if the return reaches 200. radiation cold returns hot. Maybe a banging pipe limit LOL. As mentioned could be a "heat established" sensor for a heat timer as mentioned above but not wired that way

    Tinman
  • Tinman
    Tinman Member Posts: 2,808
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    R and D is a very popular steam control manufactured and used here in Chicago. I see that one more than Heat Timer or Tekmar.
    Steve Minnich
    Mike
  • KC_Jones
    KC_Jones Member Posts: 5,741
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    To detect steam at end of main for timing the cycle perhaps?
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
    Tinman
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,516
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    Steve I have seen aquastats used to keep the burner at low fire until the boiler water reaches a certain temperature.
    Ray Wohlfarth
    Boiler Lessons
    Tinman
  • Tinman
    Tinman Member Posts: 2,808
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    Thanks guys. I bet that's what it is, Ray. The aquastat for low fire and the operating pressuretrol for high fire?
    Steve Minnich
  • Tinman
    Tinman Member Posts: 2,808
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    Two stage Weil LGB-12
    Steve Minnich
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,516
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    @Steve Minnich Typically The operating control was set for the desired operating pressure and the aquastat will keep the boiler at low fire until the temperature reaches the setpoint. Once it does, the burner goes to high fire until the call the firing rate or operating control changes it
    Ray Wohlfarth
    Boiler Lessons
    Tinman
  • Tinman
    Tinman Member Posts: 2,808
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    Thanks Ray. I appreciate the help.
    Steve Minnich