Energy efficiency class of circulation pumps – what A, B, C mean and how much you can save
Energy efficiency class of circulation pumps – what the letter A, B or C hides and what it means for your energy bill
When a customer buys a circulation pump, most of them look at three things: price, connection size and brand. Energy efficiency class? Unfortunately, it often falls out of the field of view. Yet this small letter – A, B or C – can decide over the course of ten years of operation whether you have saved or overpaid several hundred euros on heating. In this article, we will examine the energy efficiency classes of circulation pumps in depth – from legislative foundations, through technical principles, to concrete calculations from everyday practice.
Why energy efficiency classes for circulation pumps were introduced in the first place
Circulation pumps are relatively inconspicuous devices in terms of electricity consumption in buildings. The power consumption of a single pump is in the tens of watts – but when we realize that about 120 million circulation pumps are operating in households, commercial buildings and industry in the European Union, the overall picture is different. It is estimated that pumps consume about 10% of all electricity in the EU – and a significant portion of this consumption comes precisely from inefficient, outdated models without regulation.
The European Commission responded to this problem with the ErP regulation (Energy-related Products – energy-related products), specifically Regulation No. 641/2009 and its later amendment No. 622/2012. These regulations introduced mandatory minimum requirements for the energy efficiency of circulation pumps and at the same time defined the system of the energy efficiency index EEI (Energy Efficiency Index), which forms the basis of classification.
As of January 1, 2013, pumps with fixed speed without electronic regulation – i.e., old three-speed pumps that were the standard for decades – were practically eliminated from the market. Since 2015, stricter limits also apply to pumps intended for heating circulation systems. Today, when you buy a pump with an energy efficiency class label, you are purchasing within a system that is a legislatively anchored European standard.
What is EEI – the energy efficiency index
The core of the entire energy efficiency classification system is the number EEI – Energy Efficiency Index. It is not about absolute energy consumption, but about the relative efficiency of the pump compared to a reference model. The lower the EEI number, the more efficient the pump is.
Calculating EEI is not trivial – it takes into account the weighted average hydraulic power of the pump at various operating points during a simulated heating season. In other words, the pump is not tested in just one point, but in a series of load conditions that simulate real operation throughout the year. The resulting EEI thus indicates the average energy demand of the pump under real conditions – not at maximum performance, where the results could be misleading.
An EEI value ≤ 0.23 places the pump in class A. Values from 0.23 to 0.40 correspond to class B and the range from 0.40 to 0.60 to class C. Old three-speed pumps without electronics had an EEI higher than 1.0 – i.e., more than four times worse than today's class A pumps.
Class A: what it specifically means and why it is the standard today
Class A is practically an essential standard for any new circulation pump intended for a single-family home or apartment building. Class A pumps are equipped with electronically commutated motors (ECM – Electronically Commutated Motor), sometimes also referred to as permanent magnet motors. These motors have significantly higher efficiency compared to old asynchronous motors – while the old asynchronous motor had an efficiency of 30–50%, the modern ECM motor achieves 80–90%.
In addition to the motor, the key component of class A pumps is integrated electronic regulation – the pump itself evaluates the hydraulic resistance of the network and continuously adjusts the speed accordingly. Most class A pumps offer several automatic modes:
- Constant pressure (ΔP-c): the pump maintains a set differential pressure regardless of the flow – suitable for systems with thermostatic valves, where the flow changes.
- Proportional pressure (ΔP-v): the pump reduces pressure in proportion to the reduction in flow – more energy efficient for most classic heating systems.
- Constant temperature or temperature difference: some models regulate based on temperature or the temperature difference in the supply and return.
- Automatic (Auto) mode: the pump itself evaluates the most advantageous method of regulation according to current conditions.
How to correctly set these modes after installation is discussed in more detail in the topic Setting up a circulation pump after installation – manual vs. automatic mode.
Class B: a transitional class that is losing its justification today
Class B in practice includes pumps that have a certain form of electronic regulation (e.g., electronic speed setting with a 3-step switch), but their motor is still asynchronous or the control is less sophisticated. These pumps met the original requirements of the ErP regulation from 2013, but since 2015 the limits have become stricter and class B is approaching the minimum boundary in many power categories.
In practice, class B pumps are still available on the market as so-called outdated models or clearance items. From the point of view of energy efficiency, they are better than old pumps, but significantly worse than class A. For a new installation, it does not make sense to buy them if you plan long-term operation – the difference in consumption will be paid back in electricity costs within a few years.
Class C and old pumps: how much extra it costs you
Class C exists today more as a reference point – new class C pumps are legally sold only exceptionally (e.g., for certain special applications outside of standard heating). If you have a class C pump in your house or even an old pre-electronic pump with an asynchronous motor without any regulation, you are very likely paying unnecessarily tens of euros extra every month.
A concrete example from practice: In a single-family house with a floor area of 180 m² and a classic heating system (radiators, boiler, design for a pump with a flow rate of 2 m³/h and a head of 4 m), an old pump with a typical power consumption of 80 W without regulation was installed. The heating season lasts about 200 days, the pump runs 24 hours a day – that is 4,800 hours a year. Consumption: 80 W × 4,800 h = 384 kWh annually. At an electricity price of 0.22 €/kWh, this amounts to 84.5 € annually.
The same pump replaced by a modern class A pump: the average actual power consumption in real operation (due to regulation and proportional pressure) is around 10–15 W. Consumption: 12 W × 4,800 h = 57.6 kWh per year. Annual costs: 12.7 €. Difference: more than 70 € per year, i.e., over 700 € in 10 years of operation.
How energy class really affects consumption – physical principle
To understand why the difference between classes is so dramatic, we need to briefly stop at the physics of the pump. The power consumption of a circulation pump depends on flow and pressure, but these values are not fixed – they change depending on the current load of the system. When thermostatic valves on radiators close (which happens in warmer weather or at night), the flow in the system decreases. An old pump does not react to this – it runs at the same speed, consumes the same amount of electricity, and the result is increased pressure in the system, noise, and waste.
A modern class A pump with a pressure sensor or software-based pressure simulation detects the increase in differential pressure and immediately reduces the speed. And here comes the key physical law – the affinity laws (similitude laws): the power consumption of the pump changes with the third power of the speed. This means that if the pump reduces its speed to 70 % of the original value, the power consumption drops to 0.7³ = 0.343, i.e., only 34 % of the original value. At 50 % speed, the power consumption is only 12.5 % of the maximum!
This is precisely why the difference in consumption between a regulated class A pump and an unregulated pump is so huge – it is not a matter of tens of percent, but of multiples. In real operation of the heating system, the pump most of the time works at partial load, and it is precisely there that regulation brings the greatest benefit.
More about hydraulic principles, flow, and pressure can be found in the topic Hydraulic parameters of a circulation pump: flow, pressure, and power.
Practical calculation of savings when switching to a class A pump
Let us show the calculation more concretely on three typical scenarios that we commonly encounter:
Scenario 1: Family house, classic system with radiators
Area: 150 m², gas boiler, old pump with power consumption 65 W without regulation, annual operation 4,500 hours (187 days × 24 h). Annual consumption: 65 × 4,500 = 292.5 kWh = 64.4 € (at 0.22 €/kWh). After replacement with a class A pump with average power consumption 10 W: 10 × 4,500 = 45 kWh = 9.9 €. Annual savings: 54.5 €. Cost of a class A pump: around 70–120 €. Payback period: 1.3 – 2.2 years.
Scenario 2: Apartment building, 12 apartments, three circuits
Here are three pumps, each with power consumption 120 W. Total power consumption without regulation: 360 W. Annual operation 5,000 hours (including year-round heating of DHW). Annual consumption: 1,800 kWh = 396 €. After replacement with three class A pumps (average power consumption of each 18 W): 54 W × 5,000 h = 270 kWh = 59.4 €. Annual savings: 336 €. Cost of replacement (three pumps + installation): approx. 900 – 1,400 €. Payback period: 2.7 – 4.2 years.
Scenario 3: Recreational cabin, seasonal operation
Here the picture is different. The pump runs only 90 days a year (2,160 hours). Old pump 60 W: 2,160 × 0.06 = 129.6 kWh = 28.5 €. Class A pump, average power consumption 9 W: 19.4 kWh = 4.3 €. Annual savings: 24.2 €. Payback period for a pump costing 70–100 € is 3–4 seasons. It still pays off, just a bit slower.
Energy classes and subsidies – what you need to know
When reconstructing heating systems within various subsidy schemes (such as the Green Family Program, ŠFRB subsidies, or EU funds for apartment buildings), the requirement for the heat pump's energy class is increasingly appearing as one of the conditions. Most subsidy programs explicitly require pumps with EEI ≤ 0.23, i.e., class A. If you want to have the reconstruction costs reimbursed, using a pump of a lower class can be a reason for rejecting the application or reducing the subsidy.
When selecting a pump, always check not only the price and hydraulic parameters, but also whether the specific model meets the conditions of the relevant subsidy program you are applying to.
Where to find the energy class – label, documentation, selection
The energy class must be stated directly on the pump (label) or in the accompanying documentation according to EU legislation. In practice, it looks like this:
- On the pump body itself (usually on the display or a sticker), the EEI value or the letter of the energy class is indicated.
- In the technical documentation (user manual, technical sheet), you will find the exact EEI number and other energy parameters.
- In e-shops and technical catalogs, EEI or the energy class should always be part of the technical specifications.
Warning: some less conscientious sellers mention the energy class vaguely or omit it altogether. If you cannot find the EEI of a specific pump, it is a warning sign. A reliable seller and manufacturer always transparently provide these data.
The topic of pump selection, including other parameters, is covered in the article How to choose a circulation pump for heating – what to focus on, where you will find a comprehensive view of the entire decision-making process.
Less known brands and energy class – is there a difference?
One of the most common questions customers ask: "If I buy a cheaper pump from a less known brand with a class A label, will I really have the same consumption as with an expensive Grundfos or Wilo?"
The answer is nuanced. From a legislative perspective, every pump sold in the EU with a class A label must actually meet the EEI ≤ 0.23 requirement – the manufacturer is required to prove this through testing. So, in terms of basic energy efficiency, the difference should be minimal.
Where less known brands may differ from premium manufacturers:
- Quality of the control algorithm: Premium pumps have more sophisticated software that reacts more accurately to changes in the system and can achieve even lower real consumption than the EEI guarantees.
- Diagnosis and protective functions: More expensive pumps have more extensive protective functions (protection against dry running, blocking, temperature protection), which prolong their lifespan.
- Bearing and seal lifespan: In long-term operation (10–15 years), cheaper models may show higher failure rates.
- Availability of spare parts and warranty service: Less known brands are sometimes more vulnerable in this area.
A more comprehensive view of this topic can be found in the article Less known circulation pump brands vs. Grundfos and Wilo – is it worth it?
Return on investment: when replacing a pump is really worth it
This is a question you should ask yourself before every replacement. If you have a class A pump that is 3–4 years old and working flawlessly, replacement for purely energy reasons does not make sense. But if you have:
- A pump older than 10 years with an asynchronous motor without regulation,
- A pump that makes noise, has problems with starting or shows other signs of aging,
- A pump with clearly overestimated parameters (always ran at full speed because it was oversized),
...then replacing it with a class A pump is economically justified and usually pays off within 2–4 years.
Important detail: always verify that the new pump meets the actual hydraulic needs of the system during replacement. An oversized class A pump will consume less than an oversized old pump, but a correctly dimensioned class A pump will consume even less. Read about calculating the required flow and pressure in the topic Hydraulic parameters of a circulation pump: flow, pressure and power.
Frequently asked questions (FAQ)
Is EEI the same as the energy class? What is the relationship between them?
EEI (Energy Efficiency Index) is a numerical value that expresses the relative energy efficiency of a pump. The energy class (A, B, C) is a categorization based on the EEI value. Class A corresponds to EEI ≤ 0.23, class B to values 0.23–0.40, and class C to values 0.40–0.60. EEI is therefore a precise quantitative indicator, while the class is its simplified categorization. For general comparison, the class is sufficient, but for technical analysis, it is better to work directly with the EEI number.
Can I still buy a new pump of class B or C?
Generally not – since 2015, new circulation pumps sold on the EU market must meet the EEI ≤ 0.23 requirement (class A). Pumps of classes B and C can no longer be legally sold as new products for standard heating applications. You may, however, come across sales of old stock or pumps for special applications (e.g., industrial, where exceptions exist). Always verify that a specific model actually meets the current ErP requirements.
Is it worth replacing a class A pump with a newer class A pump?
In most cases, no, unless the old class A pump is malfunctioning or is more than 10 years old. All class A pumps must meet the same EEI ≤ 0.23 limit, so the energy difference between an older and a newer model of the same class is minimal. Replacement is only worth it if the old pump shows faults, has incorrect hydraulic parameters for your system, or the new model offers a significant functional advantage (e.g., connection to a smart home system).
How long does it take for a class A pump to "earn" its price?
It depends on what you are replacing. If you are replacing an old non-regulated pump (pre-ErP), the payback period is usually 1.5–3 years for a family house. In an apartment building with multiple pumps, the payback period can even be shorter. If you are replacing a class B pump with a class A pump, the savings are smaller and the payback period longer – typically 4–7 years. With proper sizing and realistic operating conditions, an investment in a class A pump is always economically justified for a time horizon longer than 5 years.
Is it worth buying a class A pump for an old heating system with cast iron piping?
Yes, definitely. A class A pump operates efficiently even in old heating systems. It is important to set the regulation mode correctly – in old systems without thermostatic valves on radiators, a constant pressure mode or even a manual mode with a lower fixed speed is suitable. The electronic regulation of the pump itself will bring savings even in a system without thermostats, as the pump runs at lower speeds on warm days and during the night.
How can I determine the energy class of my current pump?
The easiest way is to look directly at the pump – on most modern pumps, the EEI or class is indicated on the label or display. You can also search for the technical specifications or manual according to the model number on the pump. If you are unable to find this information, look at the model label: if you see a power consumption significantly higher than 20–30 W and there is no display or regulator, it is very likely an old pump without class A.
Conclusion: energy class is not just a number on paper
The energy class of a circulation pump is one of the few technical parameters where a small difference on the label translates into a large difference in your wallet. The affinity law (the dependence of power consumption on the cube of the speed) and the electronic regulation of modern class A pumps create conditions under which the pump consumes only a fraction of what its non-regulated predecessor does in real operation.
If you have an old pump without class A in your house, an investment in replacement typically pays off within 2–3 years – and the remaining 7–10 years of the new pump's lifespan are pure savings. And since modern class A pumps are now available in all common sizes and power categories, there is practically no technical or price barrier to this replacement.
If you are considering a replacement and are unsure about choosing the right model, also see the topics Dimensional compatibility of circulation pumps – shaft distance and connection and Installation of a circulation pump – procedure, orientation and most common mistakes, where you will find practical advice for a trouble-free replacement. If you are also interested in available models of circulation pumps from less common brands, check out the selection in the category other circulation pump brands, where you will find models suitable for various types of installations.
Do you have a question about this topic?
Having trouble deciding or dealing with a specific situation in your home? Write to us – we are happy to help.