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I have tight taps in my sinks and bathroom which are difficult to control — it's either too hot or too cold and never easy to manually set the preferrable temperature. I'd like to solve this old problem electronically.

I figure I'd need (per sink) a temperature sensor, at least two motors (with belts to wrap around each valve, I don't want to interfere with the insides) and a device that polls the sensor several times per second and rotates the motors. I'd like to keep it simple and cheap.

user1306322
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    Electronics & water.. nice combo – m.Alin Jul 26 '12 at 09:21
  • @m.Alin yeah, I think I'll have to pour a ton of hot glue over everything. – user1306322 Jul 26 '12 at 09:24
  • Not sure what you mean by 'I have tight taps', which may be causing me to make a bad suggestion. Why not use a thermostat sink mixer tap? They don't require batteries: http://t2.gstatic.com/images?q=tbn:ANd9GcTKzoTiq6PBj7GBON9EtPmtPoW0LRNWK7wLHgtU3sYnCt_hejNX&t=1 – jippie Jul 26 '12 at 18:25
  • @m.Alin "Electronics & water", in an industrial electronics that is not widely known, Induction Heating, water and electricity is essential. Better known as water cooled. HOW EVER, safety must come first – Marla Dec 04 '15 at 22:06
  • Why not just pop down to your local plumber's merchant and buy a thermostatic mixer valve? No electronics required. – Simon B Dec 04 '15 at 23:41

2 Answers2

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You are most likely looking for a so called "PID controller". You can either build one yourself (with a PIC (AN964 Implementing a PID Controller on PIC16F684) or AVR (AVR221: Discrete PID controller), or get one like osPID.

A PID controller uses a control loop to feed back its output to its input (aka closed loop system). This way it checks constantly for any deviation in the (output) state/variable and tries to correct it. The output characteristic can be Proportional, an Integral, a Derivative of the input, or any (scaled) combination of the three.

m.Alin
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suha
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  • Can you give us a bit more detail about the PID controller? – Kortuk Jul 26 '12 at 10:06
  • A PID controller uses a control loop to feed back its output to its input (aka closed loop system). This way it checks constantly for any deviation in the (output) state/variable and tries to correct it. The output characteristic can be Proportional, an Integral, a Derivative of the input, or any (scaled) combination of both. – suha Jul 26 '12 at 10:19
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    @suha You should put that in your answer. Kortuk definitely knows what a PID controller is, but the OP might not know. He just wants you to give a more complete answer. – m.Alin Jul 26 '12 at 10:34
  • @m.Alin ... did that. I am still unsure how much prior knowledge I can assume and/or how to avoid baroque answers (since this a Q&A format). – suha Jul 26 '12 at 11:14
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    @suha As I see it, the more information, the better, as long as it stays on topic. – m.Alin Jul 26 '12 at 11:55
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I'll take a chance on providing some non-electronic answers:

  1. Replace the tapes. This may not be practical if you arne't comfortable with plumbing, or you have to rip apart walls.

  2. Shut off the water, remove the valve core. These usually have O-ring seals Try putting vaseline on the seals. Re-install. If still too tight, see if you can use the next size smaller O-ring. It can be either a few thousands smaller minor diameter, or 10% smaller major diameter (stretches the minor diameter more.)

  3. Take a knob off the tap to take with you, and go to DIY store or bath store and ask to see handles for disabled people. These are 3" to 6" long levers. The combination of longer lever and greater gripping surface makes them much easier to use.

In passing: A motorized solution is either going to be exposed, which is going to be seriously ugly, or hidden, which will be difficult to maintain.

Sherwood Botsford
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