If you do not have a separate hot water heater, it is possible that you have a mixing valve on your boiler and if it is open, it creates an imbalance in the system. So while you are taking a shower and someone turns on the hot water in another area of the house, the pressure on the cold side increases an follows the direction of least resistance and mixes more cold water with the hot than it normally would. As a result, the water in your shower get colder. This can happen even if the mixing valve is completely closed. In the same way, if someone turns on the cold water somewhere else while you are taking a shower set just the way you like it, the water could all of a sudden become very hot. Mixing valves were the answer years ago to mix cold water with super hot water coming from the boiler. They never work very well. So, the best way to avoid temperature fluctuations is to replace faucet with built in temperature adjusting controls. Set the temperature you want and if the pressure, hot or cold drops, the faucet will automatically adjust and the temperature to your setting. Your water pipes might come in contact or are very close to a hot water heat pipe or a heating duct. It may be in the same joist bay. When you do not use the water for a while the water near the heat source stays warm. When you turn on the water the water will seem warm at first and as the water further downstream (which has cooled off) comes up, the cooler section flows through until the hot water in the water heater gets to your fixture
Because hot water is still in the pipes from when you turned on the hot water, and when you turned on the cold faucet it had to let out the hot water first. This means you have a single-pipe sink. Double-pipe sinks have a pipe for hot and a pipe for cold and it blends them as it turns on.
You probably have a poorly insulated section of pipe. It must be between the taps and the hot water source.
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"
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.
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.
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.