Inline Circulation Pumps
Inline centrifugal circulation pumps mounted directly in the pipeline: single-phase and three-phase models for heating, cooling, and process circuits.
Products (2)
- Leo Inline Centrifugal Circulation Pump, 0.50 HP, 1 1/4" – Request a quote (out of stock)
- Sumak SML 160/80 Inline Centrifugal Pump, 1.5 HP, Three-Phase, 380V, 8 m, 42 m³/h, 1,450 rpm – $801.82
What is an inline circulation pump?
In inline pumps, the suction and discharge ports are aligned on the same axis, facing each other. This design allows the pump to be installed directly in the pipeline without requiring a separate base or frame. Inline circulation pumps with a dry-rotor centrifugal design are used in central heating and cooling circuits, hot water and process lines, air handling units, and high-flow recirculation applications.
Advantages
- Space saving: Mounted in the pipeline, it takes up minimal space in the boiler room.
- Easy installation: Easily fitted into the line with flanged or threaded connections.
- High flow rate: Reaches larger capacities than wet-rotor small circulation pumps.
- Easy maintenance: In the dry-rotor design, the motor is a standard electric motor and can be replaced when needed.
The category includes single-phase (220 V) and three-phase (380 V) models; connection sizes such as 1 1/4 inch are also compatible with small commercial systems.
Selection recommendations
Flow rate and head must be calculated based on the heat load and pipe losses in the circuit. For hot water circuits, the maximum permitted water temperature and seal type of the pump should be verified. Sufficient clearance must be left around the pump for the motor cooling fan, and mounting with the motor at the top is preferred. In systems requiring redundancy, two pumps can be connected in parallel and operated alternately.
Maintenance
In dry-rotor inline pumps, the mechanical seal is the most frequently serviced component; it should be replaced when dripping is observed. Bearing noise and vibration indicate that motor maintenance is needed. Running the pump dry damages the seal; the pump must not be started before the system is filled.
Frequently asked questions
What is the difference between an inline pump and a wet-rotor circulation pump?
In wet-rotor pumps, the motor rotor is cooled by water and there is no seal; inline dry-rotor pumps have a separate motor with a shaft seal. Inline models are preferred for larger capacities.
Can an inline pump be mounted vertically?
Depending on the model, it can be installed in horizontal or vertical lines; it is recommended that the motor not face downward.
Can it be used with cold water?
Yes; it can also be used in cooling circuits and cold water transfer.
Can a three-phase model run on single-phase power?
No; these models require a 380 V three-phase supply.
Which pump is suitable for small residential buildings?
For residential-scale systems, circulation pumps with unions are more practical and economical.