Circulation Pumps
Quiet and Compact Heating Water Circulators with Three-Speed Control
Circulation pumps are compact circulator units. They keep the fluid moving continuously inside closed heating, cooling and hot water circuits. Moreover, the three-speed motor lets you match the pump to the flow rate and head demand of the installation.
The pump body is available in bronze or corrosion-resistant cast iron. In addition, the Noryl impeller, the alumina ceramic shaft and the copper-wound motor support long service life. As a result, noise levels stay low and maintenance demand remains limited.
All model options run on a 1~230 V / 50 Hz single-phase supply. Therefore, they suit both domestic boiler rooms and light commercial plant rooms.
170 l/min Flow
Depending on the model and speed step, the pump can deliver up to 170 litres per minute.
11.5 m Head
Several model options are available for closed circuits that require a high head value.
Three Speed Steps
Pump performance and power draw can be set in three steps, according to system demand.
2°C to 110°C
The pump works across a wide temperature range under suitable pressure and fluid conditions.
What Is a Circulation Pump?
A circulation pump moves water between the pipework, radiators, boiler, underfloor heating loop, fan coil units and heat exchangers of a closed system. In short, it maintains the flow that the circuit needs.
The pump is not selected to lift the static height of the installation. Instead, it covers the friction losses created by pipes, valves, exchangers and other equipment. For this reason, the required flow rate and the total pressure drop must always be evaluated together.
Circulation pumps are therefore a core component of hydronic design. In addition, they work alongside balancing and control equipment such as multi-way control valves, which regulate how the circulated water is distributed between zones.
How Do Circulation Pumps Work?
Fluid Inlet
First, the return water from the installation enters the impeller chamber through the suction port.
Impeller Rotation
Then the electric motor turns the Noryl impeller at the selected speed step.
Pressure Build-Up
As a result, the impeller adds kinetic energy to the fluid and overcomes system resistance.
Continuous Circulation
Finally, the pressurised water leaves the discharge port and returns to the circuit.
General Technical Specifications of Circulation Pumps
| Technical Feature | Value / Option | Description |
|---|---|---|
| Pump body | Bronze or corrosion-resistant cast iron | Selected according to the application and the fluid properties. |
| Impeller | Heat-resistant Noryl | Material temperature resistance may reach roughly 150°C. |
| Pump shaft | 99% alumina ceramic | Provides wear resistance together with low friction. |
| Ceramic bearing | 99% alumina ceramic | Supports quiet running, since it is lubricated by the pumped liquid. |
| Fluid temperature | 2°C to 110°C | Must be assessed together with system pressure and fluid properties. |
| Power supply | 1~230 V / 50 Hz | The pump runs on a single-phase electrical supply. |
| Speed control | Three steps | Flow, head and power draw can be selected manually. |
| Insulation class | H | Indicates the temperature class of the motor windings. |
| Protection class | IP44 | Provides a defined level of protection against solids and splashing water. |
| Motor winding | Copper winding | Supports the electrical and thermal performance of the motor. |
| Connections | Union or flanged options | Connectors can be supplied according to the model and the pipework. |
Pump and Motor Construction
Suitable for domestic hot water lines and circuits that demand corrosion resistance.
Offers a durable and economical solution in closed heating and cooling circuits.
Low weight and corrosion resistance both support stable pump performance.
Provides low friction, wear resistance and quiet operation.
The pumped liquid cools and lubricates the rotor and the bearings.
The motor can run at low, medium or high speed, depending on system demand.
Circulation Pumps Technical Performance Table
Power, maximum flow and maximum head values are given for the three speed steps in the order 3 / 2 / 1.
| Model Size | Supply | Power Consumption (W) | Maximum Flow (l/min) | Maximum Head (m) | Connection DN | Pipe Size | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 3 | 2 | 1 | 3 | 2 | 1 | 3 | 2 | 1 | ||||
| 15-40/130 | 230 V / 50 Hz | 74 | 54 | 34 | 40 | 30 | 22 | 4.0 | 3.3 | 2.3 | 15 | 1″ |
| 15-40B/130 | 230 V / 50 Hz | 74 | 54 | 34 | 40 | 30 | 22 | 4.0 | 3.3 | 2.3 | 15 | 1″ |
| 20-40/130 | 230 V / 50 Hz | 74 | 54 | 34 | 45 | 35 | 25 | 4.0 | 3.3 | 2.3 | 20 | 1¼” |
| 21-40F/130 | 230 V / 50 Hz | 74 | 54 | 34 | 55 | 42 | 30 | 4.0 | 3.3 | 2.3 | 21 | 1¼” |
| 25-40/130 | 230 V / 50 Hz | 74 | 54 | 34 | 55 | 42 | 30 | 4.0 | 3.3 | 2.3 | 25 | 1½” |
| 25-40/180 | 230 V / 50 Hz | 74 | 54 | 34 | 55 | 42 | 30 | 4.0 | 3.3 | 2.3 | 25 | 1½” |
| 32-40/180 | 230 V / 50 Hz | 74 | 54 | 34 | 55 | 42 | 30 | 4.0 | 3.3 | 2.3 | 32 | 2″ |
| 15-50/130 | 230 V / 50 Hz | 85 | 60 | 40 | 40 | 32 | 23 | 4.5 | 3.8 | 2.5 | 15 | 1″ |
| 15-50B/130 | 230 V / 50 Hz | 85 | 60 | 40 | 40 | 32 | 23 | 4.5 | 3.8 | 2.5 | 15 | 1″ |
| 20-50/130 | 230 V / 50 Hz | 85 | 60 | 40 | 47 | 37 | 25 | 4.5 | 3.8 | 2.5 | 20 | 1¼” |
| 21-50F/120 | 230 V / 50 Hz | 85 | 60 | 40 | 58 | 45 | 32 | 4.5 | 3.8 | 2.5 | 21 | 1¼” |
| 25-50/130 | 230 V / 50 Hz | 85 | 60 | 40 | 55 | 43 | 28 | 4.5 | 3.8 | 2.5 | 25 | 1½” |
| 25-50/180 | 230 V / 50 Hz | 85 | 60 | 40 | 60 | 47 | 32 | 4.5 | 3.8 | 2.5 | 25 | 1½” |
| 32-50/180 | 230 V / 50 Hz | 85 | 60 | 40 | 60 | 47 | 32 | 4.5 | 3.8 | 2.5 | 32 | 2″ |
| 15-60/130 | 230 V / 50 Hz | 96 | 69 | 45 | 40 | 32 | 23 | 5.5 | 4.5 | 2.8 | 15 | 1″ |
| 15-60B/130 | 230 V / 50 Hz | 96 | 69 | 45 | 40 | 32 | 23 | 5.5 | 4.5 | 2.8 | 15 | 1″ |
| 20-60/130 | 230 V / 50 Hz | 96 | 69 | 45 | 53 | 37 | 25 | 5.5 | 4.5 | 2.8 | 20 | 1¼” |
| 21-60F/120 | 230 V / 50 Hz | 96 | 69 | 45 | 60 | 45 | 32 | 5.5 | 4.5 | 2.8 | 21 | 1¼” |
| 25-60/130 | 230 V / 50 Hz | 96 | 69 | 45 | 58 | 43 | 28 | 5.5 | 4.5 | 2.8 | 25 | 1½” |
| 25-60/180 | 230 V / 50 Hz | 96 | 69 | 45 | 66 | 47 | 32 | 5.5 | 4.5 | 2.8 | 25 | 1½” |
| 32-60/180 | 230 V / 50 Hz | 96 | 69 | 45 | 66 | 47 | 32 | 5.5 | 4.5 | 2.8 | 32 | 2″ |
| 21-70F/120 | 230 V / 50 Hz | 150 | 130 | 105 | 67 | 50 | 37 | 6.3 | 6.0 | 5.2 | 21 | 1½” |
| 25-70/130 | 230 V / 50 Hz | 150 | 130 | 105 | 67 | 50 | 37 | 6.3 | 6.0 | 5.2 | 25 | 1½” |
| 25-70/180 | 230 V / 50 Hz | 150 | 130 | 105 | 67 | 50 | 37 | 6.3 | 6.0 | 5.2 | 25 | 1½” |
| 32-70/180 | 230 V / 50 Hz | 150 | 130 | 105 | 67 | 50 | 37 | 6.3 | 6.0 | 5.2 | 32 | 2″ |
| 25-80/180 | 230 V / 50 Hz | 200 | 190 | 160 | 120 | 100 | 60 | 7.1 | 6.5 | 5.5 | 28 | 1½” |
| 32-80/180 | 230 V / 50 Hz | 270 | 245 | 160 | 167 | 100 | 60 | 7.3 | 6.7 | 5.4 | 42 | 2″ |
| 32-80F/220 | 230 V / 50 Hz | 270 | 245 | 160 | 170 | 113 | 65 | 7.3 | 6.7 | 5.4 | 42 | 2″ |
| 36-80F/200 | 230 V / 50 Hz | 270 | 245 | 160 | 170 | 113 | 65 | 7.3 | 6.7 | 5.4 | 42 | 2″ |
| 40-80F/250 | 230 V / 50 Hz | 270 | 245 | 160 | 170 | 113 | 65 | 7.3 | 6.7 | 5.4 | 42 | 2″ |
| 25-120/180 | 230 V / 50 Hz | 270 | 245 | 160 | 67 | 38 | 22.5 | 11.5 | 10.0 | 6.3 | 18 | 1½” |
The maximum flow and maximum head values in the table do not occur together at the same duty point. Consequently, the final selection must follow the pump curve and the calculated flow and pressure drop of the installation.
Three-Step Speed Control
Suitable where a low flow rate and a low system pressure drop are already sufficient.
Often preferred in standard heating and hot water circuits with medium flow demand.
Used where both the flow demand and the system resistance are high.
Application Areas of Circulation Pumps
In addition, chilled water circuits that serve sensitive equipment rely on stable circulation. For example, in-rack precision air conditioners depend on a steady water flow rate. Solar-assisted circuits behave in a similar way, as seen in SolarWall technology applications.
Advantages of Circulation Pumps
Installation and Operating Recommendations
Pump Selection and Safety Note
When you select circulation pumps, evaluate the required flow, the total pressure drop, the fluid temperature and the system pressure together. Furthermore, check the connection diameter, the port-to-port length and the intended duty.
An oversized pump may cause flow noise, valve noise and unnecessary energy use. However, an undersized pump cannot provide sufficient circulation. As a result, the system may heat unevenly.
For general design guidance on hydronic systems and pump energy use, you can also review the resources published by ASHRAE.
Get Technical Support for Circulation Pump Selection
Circulation pump selection depends on system flow, pressure drop, pipe diameter, fluid temperature and mounting length. Therefore, every project should be reviewed on its own data.
You can request technical support to define suitable circulation pumps for combi, boiler, underfloor heating, hot water, solar, fan coil and heat pump installations.
