What is Condensing Boiler? How does it work?

What is Condensation?

Condensation is the transformation of a gaseous substance into a liquid state by giving off heat. As a result of condensation, the gas loses heat and gives off heat to its surroundings. When the condensation event starts, the condensed gaseous substance increases the temperature of the environment as it gives heat to its surroundings. As a result of condensation, the potential energy in the structure of gaseous matter turns into kinetic energy and the temperature increases. The dew we see at dawn is an example of condensation in nature. It increases the system efficiency (combi efficiency) by recycling the energy obtained from the flue gas to the system. In this way, the boiler efficiency rises above 100%. Condensing boiler efficiency varies depending on the production technology.

What is the Working Principle of Condensing Boiler?

In combustible devices working with natural gas, the energy obtained by the combustion of natural gas is used. In addition, as a result of this combustion, “carbon monoxide” (CO) and “nitrogen oxide” (NOx) gases are also released as waste gas. With the idea of benefiting from the heat of these waste gases, “condensing combi boilers” were designed and developed. They are called “conventional combi boilers”. Conventional combi boilers have two heat exchangers. The first of these is the “primary heat exchanger”, which is in direct contact with the flame, located just above the burner. Another heat exchanger is the “plate heat exchanger”. The plate heat exchanger is fed from the primary heat exchanger. In other words, the flame first heats the water in the primary heat exchanger, and with this heated water, the cold water entering the plate heat exchanger from the network is heated to obtain hot domestic water. For this reason, these heat exchangers are also called “secondary heat exchangers”. All parts are shown with their names in the diagram of conventional combi boilers below. The positions of the heat exchanger and plate heat exchanger have been determined.

After specifying the duties of the heat exchangers in conventional combi boilers and their position in the combi in this way, we can now move on to the condensing combi boilers, full condensing combi boilers and the heat exchanger systems of these combi boilers. First, let’s talk about condensing combi boilers and the “turbo heat exchangers” in these combi boilers. In condensing combi boilers, in addition to the two heat exchangers in conventional combi boilers, there is a third heat exchanger where condensation takes place. This heat exchanger is called “turbo heat exchanger”. Its position is right next to the fan motor at the top where the fan motor is located.

The hot waste gas obtained from the combustion of air and natural gas comes into contact with this heat exchanger surface for the last time before being thrown into the atmosphere and leaves its heat there and is thrown into the atmosphere. Meanwhile, condensation water with acidic properties is also released as a result of condensation. This water must be discharged. Condensation heat exchangers are on the side of the combi boiler. In the diagram below, the comparison of conventional and condensing combi boilers is made very clearly. Unlike conventional combi boilers where waste gases are thrown directly into the atmosphere, in condensing combi boilers, these gases are first directed downwards towards the condensation exchanger by means of the fan motor, and condensation is carried out by contacting the hot waste gases with the heat exchanger surface, which has a cold surface due to the water inside.

Finally, before we move on to full condensing combi boilers, we need to define the “rich mixture”. This concept, which is very well known by automobile enthusiasts in particular, is that combustible and combustible materials are first brought together to form a rich mixture, and then they are burned in a much more efficient way by contacting the flame. is to take.

The fresh air entering from number 7 and the natural gas entering from number 11 come to the environment-friendly “premix burner” as a rich mixture through the fan motor number 10, and combustion takes place here. The waste gas released as a result of combustion is not directly released into the atmosphere, but by circulating in the spiral circular heat exchanger channels, condensation is provided and more then it is thrown out from the chimney exit number 1. In this way, maximum efficiency is obtained.

What is the Difference Between Condensing Combi and Conventional Combi?

The difference of the condensing combi boiler compared to the conventional combi boiler is that it makes use of the combustion system and waste gas. Combustion takes place in both types of devices, but after the combustion takes place in the hermetic combi boiler, the waste gas formed is given directly to the atmosphere from the chimney. The heat of the waste gas is not utilized. In condensing boilers, on the other hand, before the waste gas is discharged from the chimney, it is once again circulated inside the system in a different combustion chamber. Thus, the water coming from the radiators is reheated and the desired temperature is reached faster with less energy. Due to the internal structure designed for the realization of this system, the initial investment costs of condensing combi boilers are higher.

In addition, because it has a lower flue gas temperature, condensation water occurs in the chimney. This water, which has an acidic character, must also be connected to a drain.

By looking at these features, condensing devices work 15% better and more efficiently than normal devices. When using such a device, you can heat your place and use hot water with 15-17% less gas consumption. A condensing device can pay for itself in an average of 2 years.