Descaling the heat exchanger - what to look out for

Like all devices, heat exchangers can also be descaled. However, you have to consider a lot more with heat exchangers than with other devices. How it works, how best to proceed, and which descaler are suitable is explained here.

Preparing for descaling

The device must first be disconnected from the mains. After that it has to cool down. Only then can the hoses be removed from the inlet and outlet of the heat exchanger.

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The next step is to procure a suitable water tank that corresponds to the amount of water in the heat exchanger.

Pumping through

The descaling solution is placed in the water tank in which the heat exchanger is located. In most cases, it is formic acid with additional metal protection, but sometimes decalcifying agents with other acids are also offered. Follow the instructions for use exactly.

Descaling is done in such a way that an (acid-proof!) Pump either as a submersible pump (€ 27.34 at Amazon *) or as a suction pump that draws in the decalcifying solution and feeds it into the inlet of the heat exchanger via a hose.

Another hose, which is attached to the outlet of the heat exchanger, leads the used solution back into the vessel. A permanent flow is important, as otherwise the lime dissolved by the acid would not be transported away from the heat exchanger.

During the process, a pH value test strip should always be used to check whether the acid has changed its pH value. If it is no longer acidic (pH value significantly less than 7), it no longer dissolves lime. It then has to be replaced by a new solution. The process is then continued until no more bubbles form.

Safety measures

As always when handling acids and alkalis, appropriate caution is required. Gloves protect against acid damage on the skin, clothing should be as long-sleeved as possible and insensitive to acid splashes.

If possible, you should protect your eyes with protective goggles during the process - acid splashes in the eye are not only painful but also dangerous.

Tips & Tricks As soon as there are no more bubbles in the decalcifying solution, either the acid is no longer acidic or the heat exchanger is completely cleaned.