One of my current projects is replacing the failing tile floor of a shower stall. The tile is now gone and I made a fiberglass pan to rest upon the remaining Durock floor. In the pan is a deck made from synthetic planks. Beneath the deck I will be installing a ring of a UV LED waterproof lighting strip. The strip being controlled by an ATtiny85. My plan is that the MC will look at two inputs. One input will be looking at the temperature of the copper pipe supplying the shower head. The other I'm not quite firm about. My thinking now is to hang a short section of dummy pipe in the cavity that the pipe supplying the shower head is in and have the other input look at the temperature of the dummy pipe.
My theory is that normally the two pipes will be at or near the same temperature. I can't imagine that during a shower, the pipe supplying the shower head would not be above the temperature of the dummy pipe. So when it is, energize the LED strip. When the shower is finished it'll take some time for the pipe supplying the shower head to cool to the same temperature of the dummy pipe. This works in favor of the scheme since I would like the LED strip to remain on for some time after the shower is finished. Naturally some hysteresis will be incorporated.
Seeking some input on my plan. Is there a potential fault/problem? Perhaps a better method?
Also seeking advice on temperature sensing components to use. Since there's no precision involved I'm thinking simple would be good but I have no idea of what device to use.
Thanks - Scotty