Thinking about it some more with the aid of the heat curve diagrams, mucking about with the heat curves is probably far less effective than simply bumping up the temp by a degree during our “heat charging” sessions. Plus the scheduling for that approach is already built in!
Next question: this morning it didn’t top up the DHW tank, as the measured tank temp hadn’t dropped far enough. But we really need a full tank for the morning showers. So how can I force it to top up? Don’t want to (wake up at 4am and) manually boost it. Given that I have it scheduled for the cheap periods only, should I just tighten up the hysteresis as much as possible, so it has the highest chance of triggering? Does that seem like a plausible solution?