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Caleffi Thermostatic Balancing Valve

February 2016


The Caleffi 116 series thermostatic balancing valves (aka automatic balancing valve) are used to automatically balance the various branches of a domestic hot water circulating systems to ensure that all parts of the system reach the required temperature, as well as prevent the growth of Legionella and limit heat losses.

The recirculation circuits are usually sized according to the flow rate required for each branch, based on the allowed heat loss and the corresponding decrease in temperature along the pipe. Generally speaking, the maximum allowed temperature drop between the point of departure from the heating plant and the point of return to the latter is 5°C.

Caleffi Thermal Balancing Valve


On reaching the set temperature, the obturator, governed by an internal thermostat, modulates the closure of the hot water orifice, thereby aiding circulation towards the other connected circuits. If the temperature decreases there is the opposite action and the orifice reopens.
The thermostatic balancing valve is factory set to 55°C. Temperature setting is easy – simply remove the black top cover and set the desired temperature by turning the adjustment screw. The graded scale shows the temperatures to which the indicator can be set.

If for instance a water temperature of 55°C is needed, the valve is set to the temperature of 55°C. If the temperature of the circulating water is below 55°C, valve opens and more water will pass through. If the temperature is higher than 55°C, the valve closes. The black top cap must be screwed tightly on the valve to activate the thermostatic control (and to avoid tampering).

The valve is supplied with a temperature gauge that can be fitted to the pressure & temperature ports on the valve. The gauge allows for a quick check that the valve is balancing the water to the correct set temperature. The P&T ports can also be used to check the head loss of the valve.



There are a number of benefits of using a thermostatic balancing valve over a manual balancing valve in hot water circulating systems. Some of the main features include;

The cost of commissioning is significantly reduced.

Thermostatic balancing valves are ‘field adjustable’ and do not require any special equipment. With a simple and easy ‘set and forget’ installation and no experience required for commissioning, this greatly reduces the cost and time of commissioning. Manual balancing valves generally requires expensive equipment (a manometer) and may require experienced commissioning companies to balance the system to ensure the correct flow rates.

Accurate balancing of hot water on the return lines.

A common issue with balancing a system manually is that installers do not know the correct procedure to balance the system, and so often commissioning is a ‘trial and error’ exercise (or not done at all) which results in uneven distribution of hot water. Thermostatic balancing valves are accurate to within +/- 2°C of the set temperature which ensures thermal balance throughout the system and minimal lag for hot water delivery.

Dynamic balancing of the system is achieved.

A thermostatic balancing valve will automatically adjust to the fluctuating demands of the hot water system, thereby distributing the hot water evenly throughout the day as the demand varies on each circuit. Unlike a manual balancing valve, staged openings do not affect thermostatic balancing valves. Thermostatic balancing valve will simply adapt to any changes within the system, whereas a manual balancing valves will need to be re-balanced and commissioned any time the system is changed and can be very costly and time consuming.



The valve is also equipped with a by-pass mechanism which is used for thermal disinfection against Legionella. It is recommended to flush the system regularly, flushing one branch at a time for a recommended period of time.

The by-pass will force the thermostatic balancing valve to fully open and set the temperature control out of action. The by-pass function can be carried out either manually by simply removing the black plastic cap during the flushing period, or automatically by means of an on/off actuator.  When using automatic by-pass, the actuator can be either timer controlled or controlled by the BMS-system.



Flow Rates

The thermostatic balancing valve is only available in 20mm, and is suitable for flows up to approx. 0.1l/s, which is generally sufficient for most domestic hot water return lines. In certain applications where large circuits are used with high flow rates, the thermostatic balancing valve may be manifolded together to achieve the desired flow.


For the valve to work efficiently, a certain heat loss must be present, and since the pipes are normally insulated, insulation of the valve is not necessary. Without insulation of the valve, it will operate under optimal working conditions and temperature regulation will be more accurate. If insulation is required the valve will still function, but regulation will be less precise.

Life Expectancy

With routine maintenance, a thermostatic balancing valve is expected to operate for 20+ years. Thanks to the special design of the preassembled cartridge, the thermostat is not directly in contact with the hot water in circulation which limits potential trouble with blockage due to limescale. In addition, the preassembled cartridge containing the control components can be removed from the valve body for checking, cleaning or replacement if required.

Pump Cavitation

The 116 series thermostatic balancing valves will never shutoff 100% as some flow is required across the temperature sensor for effective operation. If there is a concern that all valves in the system close to a point where there is insufficient flow returning to the pump, then it is possible to utilise either a manual balancing valve, or a differential bypass valve for example on the index circuit in order to ensure the minimum flow achieved.



All Valve Industries has supplied thousands of thermostatic balancing valves to the market, both for new builds and retrofit installations. Please call us for some sample project references.


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