I agree with you, PKM, on the RH performance, although the "old" style controls on the Zone VI work like a charm and are much more intuitive . There is more in my case that meets the eye. Without going into details, I have a sentiment towards Zone VI and parting with it is really not a consideration, especially since the part I'm now missing will cost little compared to another timer. I have contacted SHD, but so far no response on the sensor. It does seem like it should be the same one, as the RH timer came with just a cord to plug it directly in. Thanks for the other suggestions, I'll continue my search and eventually will get the info.