This has been raised several times before by other members. As far as I can see there is still no fix. We have an expensive electric boiler and I want more control of it. Do the maths! A 6kw boiler times 40p per kwh means 15 mins costs 60p. Times 365 days means £219. It would easily pay me to put the google device in the trash and fit a Hive controller instead.
You can only set the On/Offs schedule for Hot Water on the Hour and half hour.
You can select any time in the setting and when you save it goes to the nearest half hour!
I see no logic for this. I thought it would be made more flexible but it hasn't changed in 6 years. The schedule for the Heating as apposed to the Hot water can use any time.