Heat exchangers are used in heating systems to separate two media, while at the same time transferring heat from one to the other. The focus here is on the transfer of heat from one liquid to another. However, various types of gas to liquid and gas to gas heat exchangers are also common components in HVAC systems.
There are two main types of liquid to liquid heat exchangers:
- Plate heat exchangers
- Tube heat exchangers
Heat exchangers are used in heating systems to separate two media, while at the same time transferring heat from one to the other. An example of this type of application is a heating system with indirect district heating. Here, a heat exchanger is fitted directly after the supply pipe to the building. The heat is transferred from the district heating water on the primary side via the exchanger to the secondary side. Thus, the building’s heating water is never in direct contact with the district heating water.
Plate heat exchangers are used to a large extent in the production of domestic hot water, as it is efficient, and space-saving compared with hot-water tanks.
Many types of heat exchangers exist, and can be categorised according to their purpose, such as liquid/liquid, liquid/gas and gas/gas. They can also be categorised according to their flow pattern, such as counter, parallel and cross-flow.
Certain elements of the heating system can be direct while others indirect, depending on the utility company. The district heating or boiler side of the exchanger is called the primary system. The consumer or heat emitter side is called the secondary system.
Placing the exchanger makes it possible to minimise any damages caused by leakages from the district heating system. It also prevents difficulties that may arise from pressure variations in the district heating system. Disadvantages include operational losses, lower flow temperatures, and periodic excessively high return temperatures.
Grundfos pumps are typically a part of boiler and heating systems where a heat exchanger is required.