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Easy conversion from "Break on fall" vaporstats to "break on rise" ?

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delcrossv
delcrossv Member Posts: 2,204
in Strictly Steam

Seeing a number of the older mercury vaporstats on the 'bay that are "break on fall" with the contacts on the mercury tube on the left. Is there an easy way to make these break on rise? Maybe use the 'stat to power a relay coil?

Hopefully helpful pictures:

image.png image.png
Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 27,396

    The 408B break on fall was something of an anomaly. I don't think they sold all that well — which is probably why they keep showing up on eBay and so on.

    Adding a relay is the obvious way to reverse the action, although it does require power — simple wire the coil through the vapourstat with a suitable power source, and use the normally closed contacts as your signal.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    delcrossv
  • ethicalpaul
    ethicalpaul Member Posts: 8,863

    Just take out the mercury bulb and reverse it. Just kidding, but maybe not really.

    NJ Steam Homeowner.
    See my sight glass boiler videos: https://bit.ly/3sZW1el

  • delcrossv
    delcrossv Member Posts: 2,204
    https://forum.heatinghelp.com/discussion/comment/1842439#Comment_1842439

    Doable, but not easy. Have to unglue it. @Jamie Hall 's idea is much easier.

    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.

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