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Water leakage sensor ideas

Discussion in 'Electronic Basics' started by ehsjr, Feb 2, 2006.

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  1. ehsjr

    ehsjr Guest

    My gas water heater (50 gallon) will spring a leak in the next
    two years, if past history is a reliable indicater (Replaced in
    '78, '88, and '98, neighbors also get ~ 10 years out of theirs).

    It will leak slowly, at first (again, if history repeats).

    I want to detect that and replace the thing at the first signs.
    Has anyone brewed up a sensor for that purpose? I have two
    ideas (but they are not necessarily the best):
    1) two pieces of aluminum screening separated by a piece of
    thin cardboard. Connections via stainless screws & nuts.
    2) Piece of PC board etched to have a bunch of parallel
    traces.

    The circuit is trivial and I'll use a wall wart - the question
    is what's the simplest effective sensor. The tank sits on the
    floor, so the sensor can't be directly underneath.

    Thanks,
    Ed
     
  2. Guest

    Try this thingy for $80. Kills the water for you.

    http://www.home-technology-store.com/detail.aspx?ID=1904&iorb=4764

    Or, you could replace the heater now and avoid the mess.
    GG
     
  3. John  Larkin

    John Larkin Guest

    Classic solution: a clothespin, a couple of pennies, and an aspirin
    tablet.

    John
     
  4. John G

    John G Guest


    My heater stands on concrete outside the house (temperate Australia) and
    leaks are very apparent and not messy.
     
  5. Guest

    Neither copper or aluminum are good for this application. You need
    gold. I was planning on trying a gold plated header strip for this. I
    will place multiple sensors at strategic places in the basement and the
    detection circuit will drive a relay which will disconnect the well
    pump.
     
  6. Rich Grise

    Rich Grise Guest

    I saw a helpful hint on this - don't clamp the tablet between the
    pennies - actually, you should use brass screws through the clampy
    part of the clothespin, but then put the aspirin edgewise in that
    little clothesline notch in the clothespin, so there's no aspirin-stuff
    between the electrodes.

    Cheers!
    Rich
     
  7. Jasen Betts

    Jasen Betts Guest

    Replace the electrode.
    Most water heaters have a zinc or is it magnesium electrode down their
    centre which stops them from rusting out, when the electrode becomes
    depleted they start to rust.
    Either of those will do. but if the floor's wooden i'd go with s ring of
    thumbtacks with wires soldered to alternate ones.

    Or could you drain it and slide a tray under it?

    Bye.
    Jasen
     
  8. John Fields

    John Fields Guest

    ---
    I'd cut up a sponge into little blocks and then thread two stainless
    steel wires through them long enough to surround the base of the
    heater, then bend the affair around the base of the heater and hook
    the like ends together to keep them in place. Or, make a bunch of
    individual sensors (one sponge block and two wires per sensor) like
    that and wire them up in parallel around the base of the heater.
     
  9. Rich Grise

    Rich Grise Guest

    Soak the sponge blocks in brine, and let them dry in the sun or
    something. :) For that matter, you could use blotter paper and
    a couple of alligator clips, but don't forget the brine! :)

    Cheers!
    Rich
     
  10. Dan Akers

    Dan Akers Guest

    "My gas water heater (50 gallon) will spring a leak in the next two
    years, if past history is a reliable indicater (Replaced in '78, '88,
    and '98, neighbors also get ~ 10 years out of theirs).
    It will leak slowly, at first (again, if history repeats).
    I want to detect that and replace the thing at the first signs. Has
    anyone brewed up a sensor for that purpose?"
    _____________________________________
    Re;
    I just built one for my hot water heater about a year ago. My heater
    sits in a small closet and I was concerned not only about "wet" leaks
    but also leaks that evaporate before puddling that would go
    unidentified.
    So, my leak detector has two simple sensors; one to detect liquid water
    in the pan the water heater sits in and one to detect high relative
    humidity in the closet.
    My wet leak detector simply consists of a discarded 6V wall wart cord
    with one of those concentric male plugs on the end; you know center
    positive, sleeve negative or vise-versa.
    My high humidity detector consists of a piece of cotton string,
    suspended between two stainless steel wires, that has been soaked in a
    nearly saturated sodium chloride (table salt) solution and allowed to
    dry. When dry the string does not conduct electricity, but when the
    relative humidity reaches 75%, the NaCl deliquesces and the string
    conducts. This "sensor" is simply mounted on the circuit board ( the
    string is has about 2" clearance from the board surface, to get a fair
    sample of the ambient air) and electrically parallels the "wet puddle"
    sensor which has it's cord to allow the remote location of the wet
    "sensor" in the water heater pan.
    I epoxied a magnet onto the circuit board so I could stick it on the
    side of the heater. It operates on a single, circuit board mounted, 9V
    battery and has near zero idle current. A piezo buzzer sounds when the
    wet probe gets wet or when the closet RH goes above 75%.

    Dan Akers
     
  11. John Fields

    John Fields Guest

    ---
    Frayed knot...

    NaCl is hygroscopic.

    Haven't you ever seen saltshakers with rice in them?
     
  12. ehsjr

    ehsjr Guest

    I have to ask - why gold instead of copper or aluminum?

    Thanks,
    Ed
     
  13. ehsjr

    ehsjr Guest

    Thanks to all who have replied.

    Some interesting ideas!

    Here's one from E that didn't make the board. Paraphrasing:

    Sink a stainless steel bolt into the concrete floor if it's
    on concrete (they usually are), and use it as one half of the
    sensor with the heater the other half. When the concrete gets
    wet the resistance will drop.

    Anyone know anything about that? If nothing else, it's an
    interesting experiment I could try using a cinder block.
    I wouldn't use the body of the heater - hafta scrape the paint
    off to do that. I don't think the circuit connection would
    cause electrolysis (guessing a few micro amps) - but bare metal
    on concrete isn't something I want to do. But two bolts might
    be worth considering. The advantage is that (if viable) it
    detects without a puddle - the water doesn't have to reach
    some minimum puddle height to touch the sensor.

    Ed
     
  14. Guest

    Aluminum oxide does not conduct and copper will tarnish badly at
    basement floor level. Neither will make a particularly good sensor.
    Stainless steel or almost any other off the shelf plated connector
    would be better e.g. nickel, tin, phosphor bronze are also common
     
  15. Guest

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  16. Ross Mac

    Ross Mac Guest

    This was my first thought....the sacrificial anode has disolved and your
    water heater becomes the new anode and then leaks. Change your anode rod
    every 5 years or so (just a guess based on your 10 year time period). Is
    your plumbing all copper, galvanized (my guess) or plastic? The least noble
    metal will plate out and that is where the leak will start. Perhaps you need
    a dieltric union where your water heater connects to your plumbing....good
    luck, Ross
     
  17. ehsjr

    ehsjr Guest

    Thanks. Actually I'm not trying to solve the "problem"
    of the heater leaking. My assumption, right or wrong,
    has been that these appliances have a life expectancy
    of ~ ten years in this area. It would be interesting
    to discover what the average life expectancy is, or
    should be. That said, I will investigate the idea of
    replacing the anode. I suspect it will turn out to be
    impractical, but I don't know. The reason I say impractical
    has to do with clearance above the heater. It may be
    that the thing has to be "uninstalled" to get at the
    anode. When this heater goes bad, I'll have full access to
    the defective, uninstalled unit, and can go through
    removing the old one and then replaceing it (pretending
    it is new) just to see what's involved.

    To answer part of your post - it's copper plumbing
    throughout. And to address another issue in the thread:
    there is no mess when it leaks. It sits on concrete
    in a cinder block room - part of the garage - and drains
    outdoors if it leaks. You don't see the leak in the
    garage, so it is only by happenstance you might discover
    it. The reason I want to detect it at first sign of
    the leak is to (possibly) avoid unscheduled emergency
    replacement or an unexpected cold shower.

    I appreciate the interest and replies. While some things
    may not apply to my situation - like the dielectric union
    or the mess avoidance - they are certainly valid in other
    circumstances, and belong in the thread.

    Ed
     
  18. Rich Grise

    Rich Grise Guest

    Then you should go ahead and swap out the water heater, and plan on
    replacing the anode in maybe 5 years. First, see what's involved
    in swapping out the anode - there's a possibility that it'd be
    fairly simple to disconnect the water pipes (like, use unions)
    and tilt the drained heater to slide the anode out:
    http://images.google.com/images?q=water+heater+anode

    Also, be sure to drain the sediment out periodically.

    Have Fun!
    Rich
     
  19. ehsjr

    ehsjr Guest


    Thanks.
    You're the second person to say that, and I'm puzzled by the
    idea. I'd be throwing away 20% of the thing's life, if the
    ten year figure holds true. Am I missing something?

    The maintenance you mention below may extend the life
    considerably - I don't know - but at least I "get"
    that idea.

    and plan on
    Nice link!
    Thanks again,
    Ed
     
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