[quadrifoliate]

> Of course, the water starts out cold (because the water in the hot water pipes are cold)

No, this should be considered a failure condition for a constant temperature shower. I don't care how they do it, just bleed the cold water into a separate pipe off to the side or something.

We have sent people into space, I want actual uniform temperature water.

[jerkstate]

ah, you want this, which also exists: https://www.finehomebuilding.com/2013/03/07/hot-water-circul...

the way I do it is just turn the shower on about 30 seconds before I get in, which works the same with half the piping and less energy loss due to circulating hot water (but some water loss)

[z2]

I've seen a few apartments in Asia have small electric water heaters right before the faucet. They provide instant hot water until the main boiler's hot water arrives.

[akjssdk]

This is fairly common in newish kitchens in the Netherlands too, especially if the kitchen is far away from the boiler. Sometimes even with a boiling water tap, so you don't even need a kettle anymore.