Plumbing Question...Inspired by BeerMoney's Laundry Question.

[jakethebake]

Why does hot shower water run for a certain period of time then get gradually colder?

It seems like it should just suddenly get cold all at once when the hot runs out.

The water from the water heater is all the same temp. If I set my faucet where I want it, then essentially I'm setting the hot/cold at some ratio. It seems it should cintinue at that same ratio with the hot and cold water at the same temp until the hot runs out, then suddenly I should get all cold.

However, instead it goes for awhile then gradually gets colder.

Thoughts?

Water in the tank is replaced as the hot water goes out...hence get heated to a certain point as the hot water is going out. At some point the heating capacities can't keep up with the debit of water you use hence start gradually getting colder. You could get a good ratio for a certain ammount of time...all depends on the size of the water heater.

[jakethebake]

So the hot water in the heater gets gradually colder as it's replaced with cold and not reheated fast enough? That makes sense. Thanks.

Yup.