Heat exchanger is a very important element of the boiler and plays a fundamental role in the production of heat and hot water. Its correct functioning is therefore essential and it is important to know how to intervene in the event of a problem. Let's find out how.

What is a boiler heat exchanger

The heat exchanger is indispensable both for the heating circuit of the boiler and for the domestic hot water circuit. Both circuits are connected to the exchanger which, in turn, can be a primary (connected to heating) and secondary (connected to domestic hot water) exchanger.

In fact, there are boilers equipped with a monothermal system and a bithermal system:

1. in a monothermal system, the heating and domestic hot water circuits are separate and a special exchanger is therefore provided for each of them;
2. in a bithermal system, as occurs in condensing boilers, the circuits are separate, but have the same exchanger.

Basically, the exchanger is the element that spreads the boiler’s heat. It is the place where the exchange between cold and hot water takes place: the cold water is in fact heated to allow the heating system to work. If it works correctly, it considerably reduces the boiler's need for combustion, resulting in a reduction in costs and ensuring its efficiency.

Specifically, the primary exchanger is a water container in contact with the burner, where the combustion guarantees the heating of the water. The same principle applies to the secondary exchanger which, however, exchanges thermal energy with water from the water mains to produce domestic hot water.

Some boilers have plate heat exchangers. They are a system equipped with four holes for the inlet and outlet of the heating fluid and hot water.

Regardless of the different types, the heat exchange takes place through contact and this process exposes the exchanger to accumulations of limestone and its corrosive action, which is why it is important to have boiler maintenance carried out by a specialised technician.

What happens if the boiler exchanger does not work?

Considering the important role it plays, if the heat exchanger does not work correctly the water is not warmed up and heated. The radiators remain cold and hot water is just a pleasant wish that does not come true.

The cleaning of this component is therefore also essential to ensure a long life.

Limescale above all affects the heat exchanger and its efficiency. Hard water, with its substances that generate limescale, increases the probability that it will accumulate inside. Due to its characteristic, the exchanger is always in contact with the water. It is then easy to understand, if not obvious, the need for careful cleaning.

How to clean the heat exchanger?

The cleaning operation of a dirty exchanger must be performed by a competent professional. Maintenance must be done with special equipment to remove incrustations and impurities.

The technician will proceed to remove the limestone dust, being careful not to breathe it in: one more reason to rely on qualified assistance. At the same time, during the disassembly and reassembly operations of the exchanger, it is very important not to bend the little wings that distinguish this element in order not to compromise its integrity and functionality.

Water leaking near the boiler can be an indicator of a heat exchanger mishap. On the other hand, it is also a sign of other anomalies that can originate in several components. A further reason to understand that it is not so simple to fix or intervene on it or other critical components of the boiler.

The most effective tools for cleaning the exchanger, including a plate exchanger, are chemical washes. A descaling liquid is used to circulate inside the system, thus cleaning the exchanger and the system at the same time.

How much does it cost to replace a boiler heat exchanger?

The heat exchanger, together with the electronic control unit, is among the most expensive components in a boiler. Consequently, the price for a replacement could rise to a few hundred pounds, considering that it is the "heart" of a boiler.

The annoying setback can be avoided by scheduling the necessary boiler maintenance, relying on a chosen technician.

Underestimating the signals of a malfunction can lead, over time, to a boiler lockout, with all the consequent mishaps.