What to do if there is no hot water?

If there is no more hot water coming out of the pipes in the whole house, you should first look for the problem in a careful manner. With centralized hot water preparation via the heating system, there are a number of typical sources of error, one of which can also be the cause for you.

Why is there no hot water?

Domestic hot water can be produced in different ways. The most common method for centralized hot water preparation today is a hot water storage tank that is fed with heat from a gas or oil heating system.

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The most common problems with a complete hot water failure in central hot water systems are directly in or on the way to the hot water storage tank. And mostly they have to do with wear and tear. Typical cases are as follows:

  • Cylinder charging pump defective
  • Calcification in the tank
  • Check valve defective
  • Defective sensor
  • Incorrect setting of the storage tank charging pump and heating system
  • Fuel empty

Cylinder charging pump defective

The storage tank charging pump is responsible for heating the heat exchanger with heating water. It floods the heat exchanger, which in turn heats up the drinking water reservoir. If the storage tank charging pump is defective, it must be replaced or repaired. The paddle wheel is often calcified and settles, especially after long breaks in operation (months of absence?) no longer in motion. With smaller storage tank charging pump models, you can easily remove and decalcify or replace it.

Calcification in the tank

Calcification can also prevent hot water from being drained in the storage tank itself. The memory output is particularly problematic in this regard. Blocking limescale can also settle on the heat exchanger. In order to remove limescale in the storage tank, you must disconnect the storage tank from the electricity and the water supply and empty it, either via a drain valve or by removing the cold water supply. Knock off coarse lime crystals and soak the individual components in a decalcifying solution.

Check valve defective

The check valve prevents the treated hot water from the storage tank from flowing back into the cold water pipe. If it is defective, the hot water line pressure drops and hot water no longer arrives at the taps. The defect in the check valve is usually also a calcification. To remove the non-return valve and descale it, you must switch off the heating system, close the cold and hot water supply and the hot water return and drain the remaining water.

Defective sensor

The sensor is an electronic component for determining the actual temperature, which can break at some point. Even to replace the sensor, the entire storage tank has to be decoupled from electricity and water and emptied, which is a very complex process.

Regulation error

The communication between the storage tank charging pump and the heating system must be correct. The activity times of the storage tank charging pump may only have to be set appropriately.

Fuel empty

Maybe just the fuel is empty? Such trivial causes can come to mind, especially if the mindset is too complicated.