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Water Temperature sensor?

New twine owner. Nifty gadget. Any idea of a water temperature sensor that would work with the breakout board? Intended use is to monitor a hot tub at a remote cabin at elevation to make sure water temperature stays above a certain level. If heater/electricity cuts out unexpectedly and temp drops below a threshold, email warns me and I can take action before I have a giant block of ice. Thanks in advance!


  • 6 Comments sorted by Votes Date Added
  • Once they get the code working for the analog portion of the breakout board working you might be able to use an external probe. But why would you need to? Twine will monitor the room temperature, so as long as that's above freezing your hot tub won't freeze. Of course, if power goes out you won't have wi-fi so it's a moot point.
  • The hot tub is outside at 8000 feet in elevation, often covered in snow, in a climate that will go weeks at a time below freezeing. The reference to electricy/heater is to the hot tub it self, not the cabin, so wi fi will, generally, be available at the time and isnt a moot point.

    Any word on a timeframe for being able to use an external probe?
  • A simple, cheap thermostat (eg., round Honeywell) will close its contacts when the temp drops below the setting. Set it to the lowest operating temp when the heater is running, or just below. Place the thermostat where it will be warmed by the hot tub, maybe under the cover. Run the wires into the house and connect them to the breakout board so you can get a notification of falling temps. Keep the twine inside as it may not be reliable in temps below 0.
  • This has also come up with people who want to monitor freezers. Since all Twine external monitors are essentially on/off switches, a cheap thermostat, suitably waterproofed (since the bimetal coil will work in or out of water, the only concern would be the connections to the mercury switch, and some silicone rubber would take care of those) should work. Run the wires from the mercury switch to your Twine break-out board, connect it using a transistor as described on the break-out board manual, and you'll get your warning (assuming you can get warnings by SMS or email; I can't) if the temperature of the water drops below your setpoint. One caveat, you'll probably want to run your Twine off USB power, as any external sensor is an extra power drain on the batteries; the drain is higher when the sensor is "on". Now if only the Twine team provided a "Powered by battery/Powered by USB" signal that can be used in rules, you could set up something like, "if USB power has been off for x seconds, send me a text", as well as "If water temperatures has dropped below x, send me a text" which would protect you against power failures as well as heater failures
  • Thank you for the suggestion. Anyone else care to weigh in on a water temp sensor that can directly monitor water temperature via the breakout board?
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