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One-pipe system

The one-pipe system is a series circuit of radiators.

How does this system work?

The return water from the previous radiator is the supply for the following radiator. A valve with a bypass ensures that the water temperature in the following radiator remains sufficiently high. The bypass mixes the return water from the radiator with hotter supply water. In this way, the temperature of the water that is supplied to the following radiator rises. A maximum of 50% of the hot supply water can be mixed.

Which valve set to use?

For a one-pipe system, vasco offers the mm valve set. This set has an adjustable bypass.


The output of radiators is always indicated by 75/65/20°c. However, the supply temperature of the following radiator is lower (than 75°c), therefore a correction factor is used to determine the correct output of the radiator. The complete installation must therefore be calculated correctly so that the loss of heat is compensated.