Open heating system (definition)

Open heating system — is a heating system where the water used for heat exchange can come into contact with the atmosphere. Such systems include open expansion tanks that allow air to enter and leave the system, which can result in water loss and the need for regular replenishment.

As a rule, an open heating system operates on the gravity principle and does not require automation. On the one hand, this traditional hydraulic piping of a boiler or furnace is outdated, but it is this format of a heating complex that allows achieving autonomy.

Open heating system: main features

1. Leaky system: Water is in contact with the atmosphere, requiring periodic addition of water and prevention of leaks.
2. Expansion tank: Typically located at the highest point of the system and exposed to air, this allows for compensation of changes in water volume due to temperature fluctuations.
3. Risk of corrosion: Open systems are more susceptible to corrosion because oxygen in the air can accelerate the oxidation of metal parts of the system.
4. Removing air: Since air can enter the system, it is necessary to install devices to remove air locks and prevent cavitation in the pumps.

Open systems are often used in older buildings or less complex heating installations where ease of installation and maintenance offset potential disadvantages.

In modern systems, in some cases, a gravity heating system is combined with forced circulation in case of power failure. Such hydraulics require a well-thought-out approach, but are distinguished by their autonomy and high level of comfort thanks to climate control.