Hi David

I responded to your post as a spur of the moment, but have been thinking a little more.

Maybe in your particular situation, the temperature is not critical as in an industrial chemical process; you simply have a fairly large body of water that you anticipate bringing up to and maintaining a temperature within say +/- 2 DegC. Although the thermal characteristics of ABS pipework are very poor you could use this to your advantage, why not simply attach the 1820 directly to the outside of the pipework, AND insulate heavily around the section. You could mount the 1820 directly onto a wide metal band as a type of thermal heat plate.

Better still why not adapt the idea of a bog standard floating pool thermometer. Mount the 1820 at the bulb location; open up the float ball place circuitry, power supply, and a small RF unit inside, even turn the ball into a sexy multicolour “Light glow ball” to reflect the readiness of the tub! Have the RF transmitter send to a LCD or Oled display that you keep in the house, integrate another RF unit into the control panel and Viola. Hook another RF up into a USB dongle and keep an eye on things online, or have it send text updates to your mobile.

What a neat little run of projects all easily achievable and conjunctive, without having to use MPLAB IDE!

Now I wonder if the humidity phase boundary at the surface of the water would excessively interfere with the RF? Would 2.4Ghz be more reliable than 433 etc. I can’t off-hand remember.

I am probably not helping at all here, but am having fun.

Duncan