Improve efficiency: Heat the hot water when it's cold

[Timbones (Tim)]

@MyForest

I solved your problem by switching to DHW at the moment the algorithm was about to stop space heating.

But if the heating never stops…

@MyForest

I guess this doesn’t help because you’re trying to do it on-board in the FTC to keep life simple.

I am actually sending “Force” command from a cron job, with some simple logic to decide if it wants to or not. Worst case, if internet happens to be out at that exact time, I can to force it on manually via internal controls.

@MyForest

If you set the scheduled timer for DHW (say at 14:00) and the “only heat when it’s dropped 15 Celsius below target” does that allow space heating to run under Cosy from 1-> 2 and then (optionally) do DHW or just keep space heating?

Prohibiting the hot water during the other 23 hours with a large “DHW max. temp. drop” setting would in theory achieve the same effect. However, I found that the Ecodan would heat the water whenever it wasn’t prohibited, regardless of the tank temperature. [@mjr noted the same here]

@MyForest

Unless you are a smarty like Timbones and you have a battery

I do have a little rule that boosts the heating by 0.5° at noon if there’s sufficient battery left, knowing that it’ll be replenished an hour later.

My overall heat pump strategy now is to be mostly using manufacturer’s out-of-the-box controls, with some optimisation tweaks and nudges over the top. If my hacks fail for some reason, the basic operation continues to function.