Do a search for "Qwaterback" made by Paragon. As a previous poster
mentioned, it is a servo type thing that mounts to the thermostat, that
turns it up/down in response to the timer. I picked one up (new in the
box) at a yard sale some time back, and gave it to a friend since my w/h
is electric. For some reason, the instructions specifically say not to
use it on a propane unit, which is what he has, so he did not use it.
Next time I talk to him, I'll ask if he still has it. Larry