Not all Plumbing devices do; some have combined hot/cold taps. In either case, hot and cold water lines are separate, the hot water coming from a water heater. The simplest taps merely control each line, letting the user measure out how much of each they want.
They don't have to, this is a very old fashioned way of installing a sink with running water. Here you can see more info: http://en.wikipedia.org/wiki/Faucet
No, cold water is piped into the hot water tank and is heated by electricity or gas, it then flows out to the hot water taps.
Usually there are no letters on French taps; some old taps bear the letters C (for chaud = hot) and F (froid = cold). Hot water taps are always located on the left side, cold water taps on the right. It is also standard to find color marks (blue for cold, red for hot) on the taps. On newer models, having a central lever instead of two taps, you turn the lever to the left for hot water and to the right for more cold water. Also the blue and red marks may be found on these type of taps.
Very easy once the supply lines to both the hot and cold water supply are shut and then work can proceed on changing out the "taps"
that happens because cold water is heavier than hot water.
The aerator to the cold taps may be jammed, otherwise check to see that the cold water valve is switched on.
The cutoff valve from the hot water heater may have been closed.
if someone put in a hot water tank they may have the lines switched.
If possible, install hammer arrestors in hot and cold water mains.
Mixer taps are extremely easy to use and one does not constantly have to try and get the perfect temperature and mixture of hot and cold water. Also one can make sure that hot water is not being overused.
It means hot water while the blue side means cold
By turning on the existing hot and cold water tap and running into a bucket, you will eventually get hot water out of one of them. The hot water is usually insulated. Cold water may also be insulated in the cold climate areas to prevent freezing. The taps are usually marked "H" or "C" or by color red and blue.
F, for frio (cold). Unfortunately, the hot water tap is marked C, for calor (hot), which could cause confusion. Fortunately, many taps use a color code as well : Red for hot water and Blue for cold water.