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Brass Thermowell for boiler tap?

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JaymeHart
JaymeHart Member Posts: 71
in Strictly Steam

Is brass the right material for a 1/2" thermowell in the boiler cast iron block?

Comments

  • hot_rod
    hot_rod Member Posts: 27,262

    Brass, copper and stainless are options.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • JaymeHart
    JaymeHart Member Posts: 71
    https://forum.heatinghelp.com/discussion/comment/1882710#Comment_1882710

    Is there anything I need to consider with brass?

    My plan was to use both Teflon tape and pipe joint compound to seal it.

    I definitely dont want to deal with galvanic corrosion and have to replace the boiler in 10 years.

    Corktown
  • hot_rod
    hot_rod Member Posts: 27,262

    Pretty much all the trim and safety valves screwed into a cast block are brass or a brass alloy. Same with stainless, copper, steel and aluminum block boilers. Occasionally you see stainless wells in some high efficiency boilers.

    Yes teflon tape with a smear of teflon thread dope is a common method, for threading into the boiler.

    Do you have a failed well? If so what material is it?

    Some wells are a brass connection with a thin copper tube as the well. Those have been known to pin hole from aggressive water often.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • pecmsg
    pecmsg Member Posts: 7,007

    a little Teflon and never-seize

  • JaymeHart
    JaymeHart Member Posts: 71

    No, not a failed well. Just adding a new well to add a aquastat for my hot water loop, so I can control the boiler firing better when just that hot water loop is calling for heat.

    Currently, there is an unused 1/2" tap below the LWCO line, which right now is sealed with a black iron plug.

    hot_rod
  • pecmsg
    pecmsg Member Posts: 7,007

    concentrate on getting that plug out first.
    easier said than done

    hot_rod
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,051

    Or use a strap on aquastat.

  • hot_rod
    hot_rod Member Posts: 27,262

    Good point @EBEBRATT-Ed

    consider an electronic setpoint control with a thermistor probe

    Take a hose clamp and fasten it to the pipe coming off the boiler, a piece of insulation around the probe

    It is probably less$$, has more adjustability , and digital display
    .
    Skip the well and drain down😉

    IMG_1846.jpeg
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • JaymeHart
    JaymeHart Member Posts: 71
    https://forum.heatinghelp.com/discussion/comment/1882729#Comment_1882729

    just installed a month ago, and I see some teflon tape around the plug.

    1000010819.jpg

    Therenis an existing aquastat for the hot water loop, but it was installed on the pipe out of the boiler. Which would have been fine, but the plumbers had no idea I needed a bypass loop/mixing vale to keep it from flash boiling. When I called them, they insisted it was plumbed properly. It wasnt. I was getting loud flash steam in the hot water loop when the boiler was calling for steam for my main line.

    1000010234.jpg

    So I had to remove that drain, and plumb in that bypass loop myself.

    Now, that exisiting aquastat is right between the water flows, and the water temp at that junction is of course quite variable.

    1000010902.jpg

    I ordered a new digital thermometer/aquastat to plug into the boiler and measure the water temp there. unfortunately, I dont have anywhere else to put it without having to break into the copper lines. And I have no interest i doing that right now.

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