What Is a Motorized Valve?

A motorized valve is a control valve used in mechanical piping systems to automatically control water flow.

These valves open and close by means of an electric motor or actuator.

Motorized valves are especially used in the following systems:

• central heating systems
• underfloor heating systems
• fan coil systems
• chiller systems
• air handling units

In these systems, the valve, thanks to automation, provides temperature and flow rate control.

How Does a Motorized Valve Work?

Motorized valves consist of two main parts:

1️⃣ valve body
2️⃣ actuator (motor)

Thanks to the signal coming from the system, the actuator opens or closes the valve.

The control signal usually comes from the following devices:

• room thermostat
• building automation system
• temperature sensors

This way, the system is controlled automatically.

Types of Motorized Valves

Motorized valves can come in different types depending on the intended use.

2-Way Motorized Valve

It fully opens or closes the water flow.

It is generally used in the following systems:

• fan coil systems
• radiator systems
• air handling units

3-Way Motorized Valve

It is used to direct or mix the water flow.

Areas of use:

• underfloor heating systems
• boiler systems
• chiller systems

Motorized Valve Selection Criteria

Many factors must be considered when selecting a motorized valve.

1️⃣ Flow Rate

The first value that must be calculated when selecting a valve is the flow rate.

Flow rate calculation formula:

Q = 0.86 × P / ΔT

Q = flow rate (m³/h)
P = heat load (kW)
ΔT = temperature difference

This calculation determines the amount of water circulating in the system.

2️⃣ Kv Value

One of the most important parameters in motorized valves is the Kv value.

The Kv value is calculated with the following formula:

Kv = Q / √ΔP

Q = flow rate
ΔP = pressure difference across the valve

This value determines the valve capacity.

3️⃣ Valve Size

The valve size must be selected to match the pipe diameter of the installation.

The most common sizes:

• DN15
• DN20
• DN25
• DN32
• DN40

An incorrect size selection can reduce system efficiency.

4️⃣ Pressure Class

Motorized valves operate at specific pressure values.

In HVAC systems, the pressure class

PN16

is generally preferred.

5️⃣ Actuator Type

Actuator selection is very important in motorized valves.

Actuators can operate with the following signals:

• on/off control
• 0–10V control
• 3-point control

The actuator must be selected to match the building automation system.

Motorized Valve Brands

There are many quality motorized valve manufacturers in the mechanical installation industry.

The most widely used brands are:

Danfoss Motorized Valves

Danfoss is one of the world leaders in HVAC control equipment.

Siemens Motorized Valves

Siemens manufactures motorized valves compatible with automation systems.

Honeywell Motorized Valves

Honeywell is especially widely used in residential and commercial systems.

Caleffi Motorized Valves

The Italian manufacturer Caleffi is known for its quality products in hydronic systems.

ESBE Motorized Valves

A brand frequently used in underfloor heating and mixing systems.

Where Are Motorized Valves Used?

Motorized valves can be used in many different systems.

Main areas of use:

• underfloor heating systems
• fan coil systems
• boiler rooms
• chiller systems
• air handling units

In these systems, the valve provides temperature and flow rate control.

Common Mistakes in Motorized Valve Selection

The most common mistakes made in the field are:

• choosing the wrong Kv value
• selecting a valve that does not match the pipe diameter
• wrong actuator type
• not calculating the pressure difference

These mistakes can seriously affect system performance.

Motorized Valve or Thermostatic Valve?

In some systems, a thermostatic valve can be used instead of a motorized valve.

However, in large systems, the motorized valve is generally preferred.

Because:

• it can work with automation systems
• it provides more precise control
• centralized control is possible.

Conclusion

Selecting a motorized valve is quite important for the efficient operation of mechanical installation systems.

The following factors should be considered when making the right choice:

• flow rate calculation
• Kv value
• valve size
• pressure class
• actuator type

A motorized valve selected according to these criteria makes the system more efficient and safer.