Why is it that cold water comes out of the tap at a higher pressure than hot water?

Answer 1

Probably the lengths of the pipes, depending on how the pipes are routed, the hot water may have to travel to the water heater and back before reaching the tap, while the cold may take a more direct route.
However, the viscosity of hot water is less than cold water, so if all the piping was equal, the hot water would lose less pressure in the piping, and come out of the tap faster.

Answer 2

If this is true of your house, it is because you have a gravity fed hot water system with a cold water header tank. The hot water pressure is then given by the height of the hot tank (or if it is sealed and connected to a header tank the height of the header tank) above the faucet. Usually this is in the loft space, so the pressure will be about 1/3 bar upstairs and 2/3 bar downstairs. Mains water is at about 2 or 3 bar.

Many modern systems use combination boilers which heat the water on demand. For these the pressure at the tap is exactly the same for both hot and cold.

Answer 3

The cold water generally arives at your home at a pressure set by the supplier and is usually fairly high.
From this supply, some water is branched off to pass to a water heating system which isn't normally a pumped system.
The cold water is fed to a head tank supplying a cylinder. The head tank is float controlled.
Water from the bottom of the tank is fed through the water heating system most likely gravity fed.
As the water heats up, convection carries the hot water back to the tank from where it goes to your hot water line.
The pressure of this is dependent on the height of the tank.
above your taps. A height of about 15 feet will only give a pressure of about 7 psi...much lower than the cold water supply. When you take a bath or shower, do you have to wait some time for the water to heat up again ?? ..Slow isn't it ?

Answer 4

This may be a consequence of Bernouli's principle, which states that as the movement of fluids increase, their pressure decreases. The water altogether from the cold stream moves as fast as the hot stream, but the hot stream has more thermal energy than the cold stream, thus having more molecular movement than the cold stream. So the hot stream less pressure than the cold stream.

Answer 5

it depends on the pressures maintained in the reservoirs of hot and cold water which feed the tap

Answer 6

The pressure is the same, but the visible flow rate may not be. If the water is hard, heating it will cause calcium deposits to precipitate out and line the pipes, restricting the flow rate. It is possible that the valve washer in the hot water tap needs to be replaced.

Answer 7

The hot water as to travel through the water heater which adds more flow resistance

Answer 8

cuz cold water is looser than hot water. what i mean is that hot water has more molecules than cold water and the hotter the water is the slower it is coming out of the faucet.

Answer 9

All Nonsense. Here's the problem. Go get a new Water Heater. Thanks.