HK: Hot water

I moved into my house 5 months ago after 3 years in an apartment building and one thing that I absolutely miss is the quickness with which hot water appears at the faucet.  I remember this happening when I was a kid, having to leave the water running for 28 years before the water is hot and then rushing to use it before it runs out.  Even more, the water is freezing cold until it gets hot.

This is a common situation in houses I think, in particular old ones like mine.  I've seen some people in my area buy and install these on-demand hot water devices to alleviate this problem.  Some merely get one exclusively for the sink.  Our only device of that nature is the always-on hot water kettle that we use for baby-related needs primarily.  That doesn't count though, we have to fill it manually with filtered water.

Anyhow, I never had this problem in an apartment building so I was a bit surprised to see that even in a very modern building in HK there was an on-demand hot water device in the shower, like so.

Having used it, I totally want one, especially for my house.  It can make the water really really hot if desired and instantly.  Only trouble is I need one that connects to multiple faucets not just one, and this probably reduces the effectiveness a little do to the need for intervening pipe length.  Also, I'd need at least 3 of these (2 bathrooms and 1 kitchen) but even 1 would be a blessing.  Shame getting one installed is pricey.