Every wet central heating system has one: a small pump quietly pushing hot water round the loop from the boiler to the radiators and back. That is a circulator pump, also called a circulation pump or circulating pump. Because it works in a sealed loop it never has to lift water against gravity, only to overcome the friction in the pipework, which is why these pumps are so compact, quiet and frugal with energy.
We supply circulator pumps from Ebara and Lowara, from small domestic heating units up to larger commercial hydronic circulators, and can source other makes where a system needs them. The ranges are below, or call +44 1332 913500 for help choosing.
A circulator pump moves liquid, usually water or a water-glycol mix, continuously around a closed circuit. The classic case is a hydronic heating or cooling system, where it carries heated or chilled water from the boiler, heat pump or chiller out through radiators, underfloor loops or fan coils and back to the source.
The closed loop is the key to its design. With the water column in the return leg balancing the column in the flow leg, the pump never fights gravity; it only has to push against the frictional resistance of pipes, fittings, valves and emitters. That is a far smaller job than supplying or transferring water in an open system, so circulators are much smaller and lower-powered than the pumps used for those tasks.
Under the casing a circulator is a centrifugal pump, a small impeller spinning in a volute to create flow. What sets it apart is the closed-system design: a compact body, low head of roughly 2 to 8 metres, quiet running, and on most current models an electronically commutated permanent-magnet motor with variable speed.
That variable speed is where the savings come from. As thermostatic radiator valves close in rooms that have reached temperature, the pump throttles back to match the lower flow. Modern EC circulators draw a fraction of the power that older fixed-speed units did, and swapping an old pump for a new one often pays for itself in months rather than years.
Wet-rotor circulators are the standard for domestic and light commercial heating. The rotor runs inside the pumped liquid, which cools and lubricates the bearings, so there is no mechanical seal to fail. They are practically maintenance-free and very quiet. The Ebara Ego and Lowara Ecocirc ranges we stock are both wet-rotor.
Dry-rotor circulators handle the higher flows and heads of larger commercial and industrial systems. A mechanical seal separates the motor from the liquid; they are more powerful but need occasional seal maintenance.
Solar circulators are built for solar thermal circuits, rated for higher temperatures and glycol mixtures. The Lowara Ecocirc D5 Solar is made for this duty.
Commercial hydronic circulators are larger variable-speed units for commercial heating, chilled water and condenser circuits, typically flange-mounted at DN40 and above with control interfaces for building management integration.
A circulator is set by two figures: the flow the system needs (from the heat load and the design temperature difference) and the head it must overcome (the friction of the circuit at that flow, the index run). The duty point wants to sit on or near the best-efficiency point of the curve. Oversizing is the usual error and brings flow noise, wasted energy and balancing trouble; variable-speed models are more forgiving because they modulate down, but the base selection still matters.
We supply circulation pumps from Ebara (the Ego range) and Lowara (Ecocirc and Ecocirc D5 Solar), both high-efficiency, ErP-compliant and variable-speed, and can source other makes when needed. Give us the system details on +44 1332 913500 and we will help you choose.
If your questions have not been answered here, get in touch with our team for more information.
A circulator pump moves liquid around a closed piping loop, most commonly hot water in a heating system. Unlike open-system pumps, it only needs to overcome friction in the pipework, not lift water to a higher point, so circulator pumps are compact, quiet and low-powered. They are the standard pump type in virtually every domestic and commercial heating system.
A circulator pump is designed for closed-loop duty where it only overcomes pipe friction. A standard centrifugal or transfer pump is designed for open systems where it must also lift liquid against gravity. Circulators are smaller, quieter and use less energy because the head requirement is much lower. If you need to move water from one place to another (tank filling, supply, transfer), you need a centrifugal pump; if you need to circulate water around a loop (heating, cooling), you need a circulator.
A modern wet-rotor circulating pump typically lasts 10–15 years. Older fixed-speed models often last longer mechanically but consume far more energy over their lifetime. Replacing an old circulator with a modern variable-speed model usually pays for itself in energy savings within one to three years.
It comes from the flow the system requires (set by heat load and design temperature difference) and the frictional head loss of the circuit. A typical domestic system needs around 0.5 to 1.5 m³/hr at 3 to 5 metres head. Oversizing causes noise and wastes energy, so send us the system details and we will help you get it right.
Yes, modern variable-speed circulation pumps are designed as direct replacements for older fixed-speed models. They fit standard connection sizes, use significantly less energy, run more quietly and adapt their speed automatically to the system’s demand. Both the Ebara Ego and Lowara Ecocirc ranges we supply are drop-in replacements for most common installations.
A hydronic circulator pump is a circulating pump used specifically in hydronic (water-based) heating or cooling systems. It circulates heated or chilled water through radiators, underfloor loops, fan coils or other emitters and back to the heat source. The term “hydronic” simply distinguishes water-based systems from air-based HVAC. In practice, most circulator pumps are hydronic circulator pumps.
