It works pretty well. Installed it early this morning (00:30) and it came on at 07:30 and heated up the storage water (76 gallons) to about 145 dF.
Wiring was pretty simple, only 3 wires. Hot and Neutral to the clock (2 left screws).
A short Hot jumper back to Common (relay 2), with the NO2 back to turn on the boiler.
I'm saving relay-1 contacts for a rainy day..
Face plate installed.
Case closed.
Dang! We just had a 15 minute grid failure! Now, I have to go reset the clock!!
Edit 19:20
We took 3 showers and did two loads of wash today. We still have 115 dF hotwater left over.
Leaving the timer as is, for now.