Choosing a Heat Pump Circulator: What the Ecodesign Rules Mean

A heat pump moves heat into your home by pushing water round a circuit. The circulator, the small pump that does the pushing, runs for long hours, so its efficiency and sizing matter. This guide explains how to choose one and what the ecodesign rules say. It is aimed at homeowners and at installers who want a quick checklist.

What a circulator does

A circulator is a "glandless" pump: the motor and impeller sit in the water with no shaft seal to leak. It moves heating water through the heat pump, pipework and emitters (radiators or underfloor loops). It does not lift water from a well or boost mains pressure. Those are different pump types.

What the rules say

The main ecodesign rule for circulators is Regulation (EC) 641/2009, which sets requirements for "glandless standalone circulators and glandless circulators integrated in products." The UK copy on legislation.gov.uk is retained EU law. From the text:

Energy Efficiency Index (EEI): from 1 January 2013, standalone circulators must have an EEI of not more than 0.27. From 1 August 2015, standalone circulators and circulators integrated in products must have an EEI of not more than 0.23.
Lower is better. An EEI of 0.23 or below is the legal ceiling in that text. The regulation also gives an indicative best-available-technology benchmark of 0.20 or less. That benchmark is not a legal limit.
A carve-out for heat pump primary circuits. The 0.27 limit from 2013 excludes standalone circulators specifically designed for primary circuits of thermal solar systems and of heat pumps. The 0.23 limit from 2015 is worded differently, so ask the manufacturer how a particular model is classed.
Drinking-water circulators (for recirculating water intended for human consumption) are outside the regulation, apart from product-information requirements.
Replacement circulators integrated in products can be exempt in some cases: those placed on the market by 1 January 2022 as specifically marketed replacements for identical integrated circulators placed on the market by 1 August 2015.

We have not verified how UK follow-on rules or later amendments apply today. The EU's electric motor regulation 2019/1781 amends 641/2009, and UK treatment may differ. Check the current text on legislation.gov.uk or ask the manufacturer for the declaration of conformity before relying on any of this for a project.

Separately, Regulation (EU) 547/2012 covers other rotodynamic clean-water pumps such as multistage and submersible types, with minimum efficiency index limits. It does not describe heat pump circulators.

How to choose, step by step

Get the design duty from the heat pump maker. They publish the flow the unit needs and the pressure drop through it. Use their figures, not a rule of thumb.
Calculate the circuit resistance. Add the heat pump, pipe length, fittings, buffer or cylinder coil, and valves.
Read the pump curve. Your flow and head should fall in the efficient middle of the curve, not at the very edge.
Prefer a modulating (variable speed) circulator if the heat pump manual allows it, because heat pump flow needs often change with load. Follow the manufacturer's control instructions.
Check the labelling. Look for the EEI on the datasheet and confirm it meets the limit above.
Check fluid compatibility. If the system uses antifreeze or inhibitor, confirm the pump is rated for it.

Installer tips

Fit isolation valves either side so the circulator can be swapped without draining the system.
Flush and clean the circuit before commissioning. Debris is a common cause of circulator trouble.
Bleed air properly. Many circulators run noisily or fail early when air gets trapped.
Record the settings you commission, so a service engineer can compare later.

Think about the whole system

A well-chosen circulator helps, but flow rates, emitter sizing and pipe size matter as much. If the heat pump is struggling, do not just fit a bigger circulator. Ask a qualified installer to review the whole circuit.

For funding, the government's Boiler Upgrade Scheme page lists GBP 7,500 for air-source or ground-source heat pumps and GBP 2,500 for air-to-air, plus an extra GBP 1,500 for oil or LPG homes until March 2027. Which parts of the UK are covered and who can apply are not stated in our source, so read the official page before planning.

[AD_SLOT]

Request a quote

Planning a heat pump or replacing a circulator? Send us the details and we will pass your request to installers.

[QUOTE_BUTTON]

General information, not engineering or financial advice. Confirm regulations and eligibility with the official sources below.