I was looking up about how domestic water heater (DHW) works, and couldn't understand the following:
considering the fact that water (and all other liquids) cannot be compressed (practically), how can they state that the tank is a " heavy metal tank that holds 40 to 60 gallons (151 to 227 liters) of hot water at around 50 to 100 pounds per square inch (PSI), within the pressure range of a typical residential water system".
Do they mean that the water shoots out of the pipe at pressure of 50-100 PSI? How can one pressurize water (or any other liquid) ? If I put a membrane in a sealed tank that separate the water from the air, and then I compress the air to lets say 50 PSI, then it can be said that the water are pressurized to 50 PSI? ( and that means that if I open a valve in water side of the tank, they'll shoot out at 50 PSI ? can you remind me how to find their velocity? it comes from bernoulli?)