A recirculating pump is the unsung workhorse of every wet heating system in the UK. Sometimes called a circulator, circulating pump or central heating pump, it's the small electrically driven device that keeps water moving from your boiler or heat pump out to radiators, underfloor heating loops, and hot water cylinders — and back again. Without it, your system simply doesn't deliver heat where it's needed.
Yet pumps are routinely chosen on price alone, then blamed when systems are noisy, inefficient or never quite warm enough. The right circulator, correctly matched to your system, is one of the cheapest ways to cut energy bills, reduce wear on the boiler, and end the cold-radiator complaints. This guide walks through the main types of recirculating pumps, where each one belongs, how to size and check compatibility, and which UK brands — led by Wilo — consistently deliver in the field.
"Since the EU's Lot 11 ErP regulation came into force in 2015, every glandless circulator on the UK market must hit an Energy Efficiency Index of 0.23 or better — that's the difference between an old fixed-speed pump pulling 80–100 W and a modern variable-speed unit running on 5–25 W. Replacing a 15-year-old pump pays back inside two heating seasons."
The four main types of recirculating pump
Not every pump is built for every job. Picking the right type starts with understanding what's actually inside the housing — and what fluid it will be moving. Domestic UK heating systems use four broadly distinct pump styles, and using the wrong one is the most common reason a pump fails early or whistles in service.
Glandless wet-rotor circulators
The standard for domestic heating. The rotor sits inside the pumped fluid, which lubricates and cools the bearings — there's no shaft seal to fail. Quiet, compact, and now universally fitted with a permanent-magnet ECM motor and variable speed control. The Wilo Yonos PICO and Grundfos ALPHA are the textbook examples.
Glanded dry-rotor circulators
The motor sits outside the fluid, separated by a mechanical seal. Used in larger commercial and light industrial systems where higher heads (8 m+), bigger flow rates, or 3‑phase power are needed. Typically flanged, like the Stuart Turner Pulse 40/80‑F220 and 40/100‑F220 pumps.
DHW (potable water) recirculators
Wetted parts in bronze or stainless steel so they can handle drinking water without corroding or contaminating the supply. Fitted to secondary hot-water loops to deliver instant hot water at distant taps. The Wilo Yonos PICO‑Z, Grundfos UPS‑1550N and DAB VS bronze pumps are designed exactly for this duty.
Underfloor heating circulators
Optimised for the high-flow, lower-resistance world of UFH manifolds. Often fitted directly to the manifold with a constant-pressure curve and a wide modulating range. The Wilo Para 25/6 SC and the dedicated UFH variants of Grundfos UPM3 are the market staples.
Where each pump belongs in your system
Match the pump to the circuit, not the other way round. Heating water and hot tap water are completely different fluids in regulatory and metallurgical terms, and a pump that's perfect for one will fail prematurely on the other. Here's how the four pump types map onto the typical UK property.
Boiler heating circuits
Closed-loop primary system on a gas, oil or electric boiler. Glandless wet-rotor circulator, cast-iron body, 130mm port-to-port, 1″ BSP — the universal replacement spec.
Underfloor heating manifolds
High flow, low head, runs almost continuously through the heating season. Use a UFH-specific circulator with a constant-pressure curve and a wide modulating range.
Hot water recirculation loops
Secondary DHW loop returning unused hot water to the cylinder. Must be a bronze or stainless-steel-bodied pump rated for potable water — never a heating-grade cast-iron pump.
Heat pump & secondary circuits
Most modern air source heat pumps have an integrated primary pump, but a separate circulator is often needed for the buffer-to-emitter loop or for a secondary low-loss-header arrangement.
Suitability: how to size a recirculating pump
Specifying a pump comes down to four numbers: the pressure head it can develop, the flow rate it can pass, the connection size and port spacing, and — for replacement jobs — what's already on the wall. Get any of these wrong and the pump will either short-cycle, overheat the bearings, or leave you with cold rooms at the far end of the property.
Pressure head (m)
How high the pump can push water against the resistance of pipework, valves and emitters. A typical UK semi runs comfortably on a 6 m head pump (e.g. Yonos PICO 25/1‑6). Larger or three-storey homes step up to 8 m. Commercial premises often need 10 m+ flanged pumps.
Flow rate (m³/h)
The volume of water moved per hour. Sized from the system's heat demand and the design flow/return temperature difference (ΔT). A standard 4-bed UK property typically needs 1.0–1.8 m³/h on the primary heating circuit.
Port-to-port & thread
The distance between pump inlet and outlet must match the gap in your pipework. Domestic standard is 130 mm port-to-port with 1″ (G1½ male) union threads. Bigger circulators step up to 180 mm and 1½″ or 2″ unions.
Duty & material
Closed-loop heating uses a cast-iron body. Open-vented or DHW duties demand bronze or stainless steel — chlorinated mains water will corrode cast iron in months. Match the pump body to the fluid, every time.
Compatibility: matching the pump to the system
Modern variable-speed pumps don't just bolt in and start running — they need to talk to the boiler, the controls, and (increasingly) your phone. Before ordering, run through this compatibility checklist so you don't end up with a pump that fits the pipes but not the wiring loom.
- Voltage and supply: Domestic UK pumps are 230 V single phase. Three-phase 400 V variants exist for commercial pumps but are rarely needed in residential property.
- Connection thread: Domestic standard is 1″ BSP (G1½ union nuts) at 130 mm port-to-port. Bigger circulators use 1¼″, 1½″ or 2″. Flanged commercial pumps come in DN25, DN32, DN40 and DN50.
- Control signal: Many newer pumps accept a PWM control input from the boiler — Wilo Para SC, Grundfos UPM3 AUTO and similar. Older boilers just switch the pump on/off via 230 V live, which any modern pump will accept.
- Fluid type: Heating-grade pumps for closed loops with inhibitor; bronze/stainless DHW pumps for secondary potable loops. Mixing these up causes early failure.
- Mounting orientation: Wet-rotor pumps must be mounted with the motor shaft horizontal. Vertical-shaft mounting causes air locking and bearing damage — always check the manufacturer's installation diagram.
- Connector and cable: Some boilers (especially Worcester and Vaillant) supply pre-wired pump connectors. Adapters such as the Grundfos ALPHAC let you fit a different pump without rewiring the boiler.
Wilo: the pump engineer's pump
Founded in Dortmund in 1872, Wilo invented the heating circulator pump in 1929 and remains a world leader in glandless circulator technology. Across our network, Wilo is the brand we reach for first when reliability and acoustic performance matter — its motors are notably quieter than many competitors at the low-speed end of the modulating range, which makes a real difference in apartments and bedrooms with airing cupboards on shared walls.
The flagship Yonos PICO series is the modern benchmark: a permanent-magnet ECM motor with variable-speed differential pressure control, a clear red LED display, single-button operation, and an EEI of 0.20 — well inside the ErP requirement. For potable water duty, the Yonos PICO‑Z brings the same control intelligence in a stainless-steel hydraulic body that's WRAS-friendly and fully temperature-rated for hot DHW recirculation. And for underfloor heating manifolds, the Wilo Para 25/6 SC delivers the constant-pressure curve and PWM signal interface that modern UFH controllers expect.
- Yonos PICO range — domestic heating circulator, 1–8 m head, 130 or 180 mm port-to-port
- Yonos PICO‑Z — stainless steel for domestic hot water recirculation
- Para 25/6 SC — purpose-built for underfloor heating with PWM control input
UK pump brands compared
Eight brands cover virtually every recirculation duty you'll meet in UK heating and hot water work. Each has a sweet spot — here's how to think about them at a glance.
| Brand | Origin | Best for | Signature range | Price band |
|---|---|---|---|---|
| Wilo | Germany | Quiet domestic heating, UFH and DHW | Yonos PICO, Yonos PICO‑Z, Para | £113–£159 |
| Grundfos | Denmark | Replacement market, smart-control homes | ALPHA3, UPM3, UPS2, UPS4 GO | £129–£495 |
| DAB | Italy | Domestic heating with digital display | Evosta3, VS Bronze | £99–£199 |
| Lowara | Italy (Xylem) | Stainless & UFH-rated circulators | Ecocirc M, Ecocirc L | £89–£149 |
| Stuart Turner | UK | Light commercial & flanged duties | Pulse Trade, Pulse F220 | £110–£850 |
| Salus | UK | Budget-conscious A-rated replacements | MP200A | £75 |
| KeyPlumb | UK | Trade-priced general replacement | K11692 | £69 |
| Onyx | UK | Value A-rated CEH pump | CEH25-60/130 | £43 |
Featured recirculating pumps
A representative cross-section of what we stock — from the Wilo workhorses to the smart, app-controlled Grundfos ALPHA3 and a value-priced Salus replacement. Each is a high-efficiency, ErP-compliant unit suitable for UK domestic systems unless noted otherwise.
The standard UK domestic replacement: 1″ BSP, 130 mm port-to-port, 1–6 m head, ECM motor with single-button differential-pressure control. Quiet, ErP A-rated, and fits virtually any modern boiler installation.
Stainless-steel hydraulic body purpose-built for domestic hot water recirculation. Same intelligent ECM motor as the Yonos PICO heating range, but rated for potable water and high temperatures around the cylinder loop.
Designed specifically for water underfloor heating manifolds, with PWM control input and a constant-pressure characteristic ideal for multi-zone UFH systems. Comes pre-supplied with cable and connector for fast manifold mounting.
The premium smart circulator. Bluetooth connectivity to the Grundfos GO Balance app for guided radiator balancing without flow meters or hand-held instruments — a real time-saver during commissioning and an efficiency gain afterwards.
An Italian-engineered ECM circulator with a clear digital display, multiple control modes and an unusually wide 1–8 m head range from a single 130 mm body. Often the right choice when an older boiler needs a flexible like-for-like upgrade.
A stainless-steel-bodied variable-speed pump from Xylem's UK-supported Lowara range. Equally at home on heating systems with aggressive water chemistry and on potable hot-water recirculation duties where a bronze pump would normally be specified.
A British-engineered ECM circulator at a working trade price. 1″ BSP, 130 mm port-to-port, 6 m head — the universal replacement spec for UK domestic boilers and underfloor heating systems alike. Backed by Stuart Turner's UK service network.
The lowest-cost route to an ErP-compliant central heating pump. A permanent-magnet variable-speed circulator with a 4–6 m head range, 230 V supply and conventional 1″ BSP unions — straightforward to swap into an existing installation.
Accessory: a swap-friendly connector adapter
Many UK boilers — particularly Worcester, Vaillant and Baxi units from the past decade — use a manufacturer-specific pump connector loom. Swapping in a different brand of replacement pump usually means cutting and rewiring. The Grundfos ALPHAC adapter saves that step and keeps the warranty-friendly factory wiring intact.
Grundfos ALPHAC Adapter — Mini Superseal to FCI
Plug-in adapter that converts the Mini Superseal connector found on many UK boiler pump looms to the FCI connector used on the Grundfos Alpha2 GO and similar replacement pumps. No cutting, no rewiring.
Need help picking the right pump?
Whether you're sizing a single replacement circulator or specifying for a multi-property project, our technical team can match you to the right brand, head, and connection size — and quote the bundle if you need cylinders, valves or controls alongside it.