I must say I would have thought that my household was very 'typical' as regards 'needs' for hot water, but that's not really relevant.
You surely must realise that my interest is not in relation to my own use but, rather, an academic/intellectual interest in trying to understand the workings of this system, and to understand why a system which was invented a long time ago, and which has some 'champions' (who believe that it offers 'clear advantages'), has been taken up by such a minute proportion of the world's population.
However, you may be pleased to know that, although it is nothing to do with the technicalities of the system (i.e. 'how/why it works and behaves), I think that I may have accidentally 'seen the light' as regards this discussion, in realising that there is some serious 'chalk and cheese' involved. It didn't 'sink in' at the time, but, on reflection, what I wrote in a recent post (coupled with a link that EFLI recently posted) has made me suddenly 'see this light'.
Throughout this discussion, I have been thinking as someone who has bought into the concept of using 'stored hot water' and therefore rarely, if ever, has a need for 'newly heated water'. However, the link recently posted by EFLI reminds me what this is all about, when it says:
So, this system is being aimed at people who have totally abandoned the concept of using stored hot water but, rather, want to heat up (from cold) just the amount of water they need for each task (be it a shower, washing up, hair washing, simple hand washing or whatever). That requires them to anticipate their need to undertake each of the tasks by setting a timer for the requisite heating time (or trying to remember when to switch it off) and then waiting that amount of time before they can undertake the task. I could do essentially the same with immersions (albeit, as you have pointed out, slightly less efficiently/quickly, because of a little mixing of heated water with cold) but there is absolutely no way that I would want such tedium and disruption in my life.
I would therefore suggest that anyone contemplating a Willis system should instead seriously consider perhaosspending their money on some decent insulation for their DHW cylinder. They would then (like I do) always have essentially unlimited amounts of immediately available hot water, immediately enough for anything (including a bath, should they choose to take one) without any hassle or need to anticipate how much hot water they would next need, and when - and if their primary/only water heating were by electricity, then they might also be able reduce costs by taking advantage of tariffs with 'off-peak' periods.
