QQs: Why is the perfect shower temperature so hard to find?
Few things in life are quite as satisfying
as standing in a shower that’s exactly the right temperature.
But that heaven never lasts forever.
Water starts to get a little cooler,
so you turn the temperature knob the tiniest bit,
and suddenly you’re being scalded in places，
you really never want to be scalded.
You try to turn the knob back
and then you’re being drenched in ice water.
There’s plenty of room for the knob to turn though,
so why is there only one miniscule spot
with the water temperature is fit for humans?
First problem is that in most buildings,
the hot water is held and heated in a water heater.
Adding really hot water to cold water, changes the temperature more
than adding the same amount of water that’s just warm.
So if the water is too hot,
tiny changes in how much hot water is sent your way
can lead to big changes in the temperature
of the mix water hitting your body.
况且 加热器里的水 温度通常非常高
And the water in water heaters is usually very hot.
It’s generally set to around 50 degrees Celsius to kill bacteria.
Although you can often turn that down
to give you a wider range of acceptable shower temperatures,
assuming you’re okay with the risk of said bacteria staying alive.
But even with water that isn’t too hot,
the spots on your temperature knob
still aren’t guaranteed to give you the same water temperature.
For one thing, small water heaters might not hold enough hot water
at any one time for a long, hot shower.
Newer buildings sometimes get around this problem
by heating their hot water on demand
instead of holding it in a water heater.
But a lot of plumbing doesn’t actually check
the temperature of the hot cold mix,
it just opens the hot and cold pipes by the right amounts.
So if someone uses some of the cold
at another faucet while you’re in the shower,
you get a burst of just hot water hitting your skin.
Combined with a water heater that’s set to high,
that makes the perfect shower temperature
a tiny moving target that’s almost impossible to hit.
This moving target problem can mostly be solved
by installing a pressure balancing valve,
which will turn down the hot water
if the cold suddenly slows down or disappear.
Even newer valves called thermostatic mixing valves give you added control
over both the temperature and pressure of your shower
using a special kind of thermostat
that changes size based on the temperature of the water around it.
If the cold water goes somewhere else,
like to a toilet that’s being flushed,
the extra hot water makes the thermostat expand
until it blocks more of the hot water from getting to you.
And when the water around it is too cold,
the thermostat contracts blocking more of the cold instead.
So other people in the house get to pee
without burning you, which is nice.
And all you have to do is set the temperature you want
by turning your showers dial to the perfect temperature,
which means you can spend less time adjusting
去尽情放松 泡澡 怎样都好
and more time relaxing or bathing or whatever.
If you’d like to submit questions to be answered,
go to patreon.com/scishow.
Don’t forget to go to youtube.com/scishow and subscribe.