By Patrick Gordon of Calafrica (

This issue Patrick looks at the Thermostatic Balancing valve.

Thermostatic Balancing Valve. Image supplied by  Patrick Gordon

Thermostatic Balancing Valve. Image supplied by Patrick Gordon

Q – How does a Thermostatic Balancing Valve work?

The Thermostatic Balancing Valve is used to automatically balance the temperature between the recirculation loops in a domestic water distribution system. This ensures that all parts of the system reach the required temperature. This model is also equipped with a bypass mechanism that is used when you are required to disinfect the system against Legionella.

So how does it work?

In domestic hot water distribution circuits, it is a requirement to prevent the growth of Legionella. This is attained by ensuring the correct temperature in the complete system. It is often difficult to achieve this due to the varied friction losses in the system. This valve is used to balance the different loops within the circuit and helps maintain a uniform temperature distribution.

A thermostatic regulator, installed on each branch of the recirculation circuit, automatically maintains the set temperature. This device modulates the medium flow rate in accordance with the water inlet temperature by means of the action of a dedicated internal thermostatic cartridge. When the water temperature approaches the set value, the Main Seat progressively reduces the passage. The medium flow rate supplied by the recirculation pump is thus distributed to the other network branches, resulting in effective automatic thermal balancing.

On reaching the set temperature, the main seat (1), governed by the thermostatic sensor (2), modulates the closure of the hot water outlet  (3), thereby aiding circulation towards the other connected circuits. If the temperature decreases, the opposite action occurs and the passage reopens, to ensure that all the branches of the system reach the required temperature.

The temperature is set at the desired value by turning the adjustment knob. The graduated scale shows the temperatures at which the indicator can be set.

After adjusting the temperature, the setting can be locked at the desired value by using the control knob. For this purpose, unscrew the locking screw at the top of the control knob, remove the knob and then put it back on so that the internal reference couples with the protrusion on the knob holder nut. When this block is used, the reference of the indication of the temperature values on the knob is lost.

To further facilitate an easy installation, a preformed insulation shell is also available.