Product detailed description

ATTACK Replacement Part - Pump RS 25/6-3-PR, 180 mm

Replacement circulation pump RS 25/6-3-PR with an installation length of 180 mm, electronically controlled, energy class A. This is an economical replacement variant suitable for a wide range of service replacements with a connection spacing of 180 mm, including ATTACK boilers and many other common installations on the market.

The designation "Replacement Part" in the name emphasizes the primary service purpose of this product – it is an affordable replacement for a faulty or outdated circulation pump with the same installation length, not an exclusive OEM part tied to a specific production line.

Energy class A – what it actually means for your wallet

European legislation (the ErP Directive / EU Regulation No. 622/2012) defines an Energy Efficiency Index (EEI) for circulation pumps instead of the old letter classes A – G, but common usage still refers to "class A" for the most efficient pumps with EEI ≤ 0.20. This pump meets this value thanks to a wet-rotor motor with permanent magnets and electronic speed control, which continuously evaluates the pressure differential in the circuit and adjusts output precisely as needed – rather than according to a fixed setting.

In practice, this brings two effects at once: lower electricity consumption (typically a few watts instead of several dozen watts for older three-speed pumps) and smoother, quieter operation without over-regulating the circuit. If your boiler or manifold has been running an old unregulated pump, replacing it with this model can reduce the annual electricity consumption for heating water circulation by tens to hundreds of kilowatt-hours, depending on the length of the heating season and the size of the circuit.

It's also worth noting that an electronically controlled pump indirectly protects the heating system itself – thanks to smooth power regulation, flow noise in thermostatic valves is reduced and wear on bearings and the seal is decreased, since the pump doesn't unnecessarily operate at an extreme power point.

Installation length 130 mm vs. 180 mm – why it matters

Circulation pumps for domestic heating circuits are not manufactured in one universal length – you will commonly encounter two most widespread center-to-center distances between the connecting threads (the so-called installation length, or "Baulänge" in German): 130 mm and 180 mm. This dimension must exactly match the distance between the inlet and outlet ports on the boiler body or the pipework into which the pump is installed – a pump with a shorter or longer installation length simply won't fit between the existing connections without modifying the piping.

How to determine which length you need:

• When replacing the original pump, directly measure the distance between the centers of both flange/threaded joints of the original pump (from the center of one thread to the center of the other).
• Check the nameplate of the original pump – the installation length is often part of the type designation (e.g., "25/6-130" or "25/6-180").
• For ATTACK boilers, you can find the recommended pump type and dimension in the service documentation or the boiler's hydraulic wiring diagram, or contact our customer service with the boiler's serial number.
• Never install a pump with the wrong installation length hoping to "make it fit" by tightening the union nuts over the gasket – this risks leaks, pipe stress, and thread damage.

The connecting thread on the pump body is generally 1½" (internal, for a union nut with gasket) in both versions, so the connection to the piping itself is the same for both lengths – only the distance between connections differs, not the thread type.

Economical service replacement with class A parameters

The RS 25/6-3-PR represents a more affordable alternative to pricier OEM parts (e.g., OT180A) while maintaining the same key parameters – energy class A, head, and flow rate. It is particularly suitable for:

• post-warranty replacement of a faulty or noisy pump with the same 180 mm installation length,
• service interventions where a purely original OEM part is not required,
• modernizing an older installation with an unregulated three-speed pump to an electronically controlled class A solution,
• situations where the price-to-performance ratio is the decisive criterion.

The "3" in the type designation (RS 25/6-3) refers to a variant with three selectable operating curves/regulation modes (e.g., constant pressure, proportional pressure, constant speed), which can be set directly on the pump's control panel according to the nature of the heating circuit – "PR" in the designation refers to the range intended for heating (not sanitary) applications.

Technical parameters

• Installation length: 180 mm
• Energy class: A (EEI ≤ 0.20)
• Electrical input: 3 – 45 W, selectable operating curves
• Maximum head: 6 m
• Maximum flow rate: up to 3.5 m³/h
• Connection: 1½" internal thread, union nut
• Medium temperature range: 2 – 110 °C
• Power supply: 230 V / 50 Hz, IP44 protection

How to read the circulation pump nameplate

The nameplate is affixed directly to the body of the pump's electronic head and contains all the information needed to clearly identify it when ordering a replacement. In addition to the manufacturer's type designation (e.g., RS 25/6, Yonos PARA RS25/6), you will find the installation length (often directly in the number after the slash or in a note below the type), the supply voltage range, maximum power input, IP protection rating, and the serial/production number of the specific unit.

If the label is already illegible (for example, after years of operation in the damp environment of a boiler room), the most reliable approach is to directly measure the installation length with a caliper or contact our customer service with the serial number of the ATTACK boiler itself – from this we can determine which pump was factory-installed in that boiler.

When it's time to replace the circulation pump

The circulation pump is a component that usually doesn't fail suddenly, but its performance and reliability gradually deteriorate with years of operation. Here are several symptoms to watch for:

• Uneven heating – some radiators or circuits are noticeably colder than others, even with thermostatic heads fully open, which may indicate insufficient pump head.
• Increased noise – humming, squeaking, or knocking during operation that doesn't disappear even after thoroughly bleeding the circuit usually indicates worn bearings.
• Frequent thermal protection trips or outages – may indicate mechanical seizure of the rotor or an electrical fault in the motor winding.
• Visible leakage at joints or around the shaft area – after years of operation, the seal or gasket may wear out.
• High electricity consumption compared to declared values – an older, unregulated pump without class A rating may consume several times more energy than a modern electronically controlled solution.

If any of these symptoms occur, we recommend replacing the pump before it fails completely, which could cause the boiler to overheat or the heating to fail at the most inconvenient moment of the heating season.

Practical installation guide

Replacing a circulation pump is a routine service task that an experienced heating technician or service engineer can complete in under an hour if the correct procedure is followed:

1. Securing the circuit. Shut off the supply and return using shut-off valves (if none are fitted, we recommend adding them at this opportunity – they will significantly simplify future servicing), and drain the water from the relevant section into a suitable container.
2. Removing the original pump by loosening both union nuts and taking it out of the pipeline, including the old gaskets.
3. Checking the flow direction marked by an arrow on the body of the new pump – it must match the direction of the heating water flow at that point in the circuit.
4. Fitting new gaskets and screwing in the pump, ensuring the electronic head remains in a horizontal position after tightening (never with the terminal box facing downward) to prevent moisture from entering the electronics.
5. Filling the circuit and thoroughly bleeding it – air in the pump is the most common cause of noise and reduced performance immediately after installation.
6. Test run monitoring the tightness of joints, noise level, and the pump's response to changes in the circuit's heat load (e.g., by closing some thermostatic heads).

Have the electrical connection to the 230 V mains carried out by a qualified person – incorrect wiring can damage the pump's electronics and poses a safety risk.

Maintenance and extending pump life

Electronically controlled circulation pumps of this category are practically maintenance-free – they contain no lubrication points or parts requiring regular servicing beyond routine inspection. Nevertheless, a few simple habits will significantly extend their lifespan and maintain the declared energy class A throughout the operating period:

• Heating water quality. Excessive sludge, rust, or air in the heating circuit is the most common cause of premature wear on the impeller and bearings of the wet-rotor motor. For older or recently plumbed systems, consider installing a dirt filter or sludge separator before the pump.
• Regular visual inspection. Once per heating season, check the tightness of the connections, the absence of corrosion marks on the pump body, and any unusual noises (humming, knocking), which may indicate air in the system or an emerging bearing fault.
• Short-term shutdown outside the season. If the pump is not operating for a long period (e.g., outside the heating season in systems without year-round circulation), it is recommended to run it briefly from time to time to prevent the rotor from "seizing" due to deposits after prolonged inactivity – most modern pumps handle this automatically via a built-in permanent self-test function.
• Frost protection. In unheated spaces (e.g., closed-up cottages, unheated technical rooms), if there is a risk of frost, either drain the circuit or use an antifreeze mixture with declared compatibility with the pump's materials.

Safety warnings

Before any work on the pump, always disconnect the 230 V power supply and wait until the pump body has cooled sufficiently – heating water can reach temperatures close to 90 °C, posing a risk of burns. Electrical connections must be performed exclusively by a person with the appropriate electrical qualification in accordance with applicable standards (STN 33 2000 and related). The pump is not intended for operation outside the declared medium temperature and pressure range stated in the technical parameters – exceeding these limits may damage the pump and endanger operational safety.

Frequently Asked Questions

What does the designation RS 25/6-3-PR mean?
RS designates a range of regulated circulation pumps, 25 is the nominal connection diameter in mm (corresponding to a 1½" thread), 6 is the maximum head in meters, 3 is the number of selectable operating modes/curves, and PR indicates suitability for heating (not sanitary) applications.

Is this part a full replacement for the OEM WILO Yonos PARA RKC (OT180A)?
In terms of hydraulic and energy parameters, yes – the same class A, head, and flow rate. However, it is an alternative, not an identical OEM part, so for warranty service requiring an original, we recommend the OT180A instead.

Can the operating curves be adjusted even after installation?
Yes, the choice of operating curve/mode is set directly on the pump's control panel and can be changed at any time according to the current needs of the circuit, for example when changing the type of heating elements.

Is the pump suitable for a mixing circuit with underfloor heating?
Yes, thanks to the selectable operating curves, it is also suitable for circuits with lower hydraulic resistance typical of underfloor heating – we recommend selecting a constant or slightly proportional pressure mode depending on the nature of the circuit.

What is the difference between RS 25/6-3-PR (OT01) and RS 25/6 without the -3 designation (OT01A)?
The OT01 (180 mm) offers selectable operating curves in addition to the shorter OT01A variant (130 mm) – otherwise, both types are similar in hydraulic and energy parameters, differing mainly in installation length and the range of adjustable modes.

Do I need to modify the piping when replacing with this part?
No, as long as the installation length of the original pump is 180 mm and the connecting thread is 1½", installation takes place in the original location without any piping modifications.

Is a manual for setting the operating curves included?
Yes, the manufacturer's manual is included with the pump, describing the individual available operating modes and the procedure for setting them on the control panel.

Is this part suitable for other boiler brands, not just ATTACK?
Yes, since it is a universal replacement part with a standard 1½" connection and a common 180 mm installation length, it can be used in most common installations with matching connection spacing, not just ATTACK boilers.

What does it mean if an error message appears on the pump's display or indicator?
Most electronically controlled pumps signal a fault condition (e.g., blocked rotor, undervoltage, overheating) via an LED indicator or blinking light. You can find the exact meaning of the signal in the included manual; if the fault persists, we recommend contacting service.

Overview of related circulation pumps in the ATTACK range

When choosing a replacement pump with an installation length of 180 mm, ATTACK offers several variants:

• ATTACK Pump Yonos PARA RS25/6 RKC, 180 mm – original OEM part recommended for warranty service of ATTACK boilers.
• ATTACK Heating Circulation Pump PR 25/6, 180 mm, class A – universal pump also suitable for other boiler brands.
• ATTACK Replacement Part - Pump RS 25/6, 130 mm – same product range, shorter 130 mm variant for a different connection spacing.

Summary

The ATTACK Replacement Part - Pump RS 25/6-3-PR, 180 mm is an affordable, fully capable class A service replacement with selectable operating curves, suitable for a wide range of installations with a 180 mm installation length.

Warranty and support

We provide a 24-month warranty from the date of shipment from stock for this product. The warranty covers manufacturing and material defects, provided the installation and operating conditions stated in the manufacturer's included manual are followed. If you have any questions about selecting, compatibility, or installing the pump, feel free to contact our customer service – we are happy to help identify the correct type based on the serial number of your ATTACK boiler or the parameters of your heating circuit.

We recommend keeping proof of purchase, and in the event of servicing on an ATTACK boiler, also stating the boiler's type designation and serial number – this will speed up any warranty claims and future identification of replacement parts.