Hard disagree with that faucet design, but is a neat idea. I like my bathroom faucet as low maintenance as it already is.
The use case for the full unmixed hot tap is hygiene (usually washing face and shaving).
I also don't want any hot water mixed in when I'm washing my hands. The water coming out of the unmixed cold tap indicates the ambient temperature of the pipes. That's a feature, not a bug.
You should use warm water when you're washing your hands.
Why?
I'm already upset enough about what the water heater water is doing to my skin and am about to go tankless under my bathroom sink!
That's by far the more practical option anyway if we truly cared about the problem instead of fawning over engineer porn. The problem is solved. This is pointless engagement about temperature preference masquerading as something more interesting.
It used to be public health recommendation (bathrooms in commercial buildings will often only have warm water, for example, because code required it).
There's been studies demonstrating that soap is what matters.
Solubility is a function of temperature.
at least in my home, both the cold and the hot water are very uncomfortable to wash my hands in, but mixing it right takes ~15s every time so i usually just accept the discomfort
there is this thing named "Single Lever Wash Basin Mixer Tap".
I think it takes time because the hot water line doesn’t immediately return hot water
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