How Hot is Your Faucet? What Color is the Water?

How hot is the water coming out of your tap? Knowing that the water in their apartment gets “crazy hot,” redditor [AEvans28] opted to whip up a visual water temperature display to warn them off when things get a bit spicy.

This neat little device is sequestered away inside an Altoids mint tin — an oft-used, multi-purpose case for makers. Inside sits an ATtiny85 microcontroller  — re-calibrated using an Arduino UNO to a more household temperature scale ranging from dark blue to flashing red — with additional room for a switch, while the 10k ohm NTC thermristor and RGB LED are functionally strapped to the kitchen faucet using electrical tape. The setup is responsive and clearly shows how quickly [AEvans28]’s water heats up.

This is version 1.5 — 1.0 rusted out, protect your projects, people! — and a forthcoming 2.0 will feature a smoother transition between colors. In the meantime, [AEvans28] had made his ATTtny code available here for anyone else similarly maligned by scalding tap water. If you are more concerned about the temperature of your wine, but don’t have the room for an appropriate cellar, get serious with this DIY satand-in.

[via /r/DIY]

26 thoughts on “How Hot is Your Faucet? What Color is the Water?

        1. Well, the item name says “Temperature Sensor” :-).
          I admit it’s not the exact same item I bought back then, but mine changes color with temperature rising. Don’t know the exact thresholds, but red definitely means hot.
          I don’t guarantee anything though. Hey, it’s AliExpress after all ;-)

          1. @Greenaum:
            The Aliexpress Part mentions a turbine in the description. But it is not clear if it really measures temperature. It mentiones 7 colors, like my showerhead, which cycles automatically. I know the temp sensitive device normalyl have only 3 colors.

          2. @Greenaum Mine definitely has a turbine and senses temperature. Now I can’t say for sure for this one but title says temperature and description says turbine. The simplest is to test because it’s so cheap.
            But let’s face it, it’s just a gadget and build quality is awful. It’s just good to show to friends and they say “Wow, awesome”. Then you can remove it ;-)

    1. I tried the ones from China but they don’t work here because of our high water pressure.

      I slowly turned the tap listening to the turbine going faster and faster thinking that it had to self destruct soon and then with a ‘Phuh’ and a splash it disappeared down the plughole.

    1. Real fix is to add a thermostatic mixing valve, to reduce the temperature of the hot water. Reducing the volume doesn’t help if you turn the tap to all the way hot. Could also just lower the hot water temperature, but that may be undesirable if you have a small water heater or are worried about legionella.

  1. Nice, but basically it needs to light up before you open the tap. I remember one occasion when I burnt myself because someone else had used it at maximum temp a minute ago (the remaining water dead- volume was still pretty hot).

    1. Hmmm…
      I’ve almost gotten frostbite because the previous user ran the water too cold.
      I guess one should never assume the water is safe; it really could have been at any temperature. :P

    2. Men have walked on the moon, I can chat with people in Brazil, even though I speak no Portuguese and they speak no English, we can edit the genetic code of living things to create new features. But can we get a shower to dispense water that is merely warm?

      1. You can If you wish to spend the money on it.
        I had an instantaneous gas system with a control pannel next to each shower. Set the desired temp and off you go.

        I just replaced it with a solar system and working on a way to use the existing control panels to regulate the temp.

      2. Yep. There are a ton of shower valves that have seperate flow and temperature controls. Set the temp you like (or remember it), turn the water on, wait for it to stabilize and you’re back in business. Not cheap (~$90 for the part), but blissfully nice. Lots of varieties, but this is what I’m talking about.

  2. I lived in an apartment building that had free hot water, and heating. The problem was we didn’t have a way to change the temperature of the water coming in, some days it’d melt your skin directly off your bones, and other times it’d be rather cool and you’d be left thinking, hmm maybe I should just boil some water myself.

    Now, we had mixer taps and it worked well once you got the hang of it. hand on top of the tap, run the hot water, wait for metal to heat up, if too hot to touch, turn cold water on too.

    The problem came with the heating. The TVR only really worked in two ways, on or off. If the room was hot enough the heating valve closed, otherwise it was open. We had a mixture of cast iron and more modern aluminium/steel, both in Victorian style column radiators, the cast iron ones tool a little time to heat up, but the aluminium ones were got in a matter of seconds, full on temp based on the water in them.

    The amount of times we’ve had been caught by a radiator suddenly getting rather hot, or brushing past or bending down and using it as prop to get back up, burning our hands, legs, butts etc. In the end we put covers on them, and dangled some string over the ones we couldn’t, so at least we could see the heat rising.

    I did try thermochromatic paint, but the temperatures were too high for what was durable enough for a radiator.

    1. Great comment, made me slightly regret my snarky comment above.

      Here’s a link to higher temperature thermochromic paint: I couldn’t find much info on materials that change reversibly around 100C°. I wanted to use color-changing paint for a solar oven.

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