Product detailed description

ATTACK Pump Yonos PARA RS25/6 RKC, 180 mm, replacement part for ATTACK boilers

Original replacement part – Yonos PARA RS25/6 RKC circulation pump with an installation length of 180 mm, identical to the pump factory-fitted in selected ranges of ATTACK boilers with a longer connection installation length. The designation "RKC" (Rohrkupplung/compact connection) refers to a specific version of the connection set used by the boiler manufacturer – the part is therefore fully compatible without any modifications.

This is a direct service replacement intended for both in-warranty and post-warranty servicing of ATTACK boilers that come factory-fitted with a pump of this series with a length of 180 mm.

Why does energy class A matter?

Under normal operation, the circulation pump is one of the few devices in the heating system that runs practically continuously throughout the entire heating season – in practice this can amount to 4,000 to 5,000 hours a year. That is exactly why its efficiency has a much greater impact on annual electricity costs than it might seem at first glance. Older pumps without electronic control (so-called "three-speed" wet-rotor pumps) always run at full or fixed output regardless of the actual heat demand at any given moment, and their energy efficiency index (EEI) typically ranges around 0.6 – 0.8, or is not declared at all.

This pump belongs to energy class A, the highest commonly available class for small circulation pumps in domestic heating circuits, with a corresponding EEI ≤ 0.20. In practice, this means that the electronically controlled permanent-magnet rotor automatically adjusts speed and flow output to the current needs of the heating circuit – under partial load (for example on transitional autumn or spring days), the pump significantly reduces its power consumption instead of continuing to run at full output. Replacing an old, non-regulated pump with this model can therefore realistically achieve electricity savings for circulating heating water on the order of 50 to 80%, depending on the original pump type and the nature of the heating system.

The lower electricity consumption of the pump is also noticeable outside the heating season if the circulation pump is also used for overrun or temperature maintenance in systems with a storage tank. With year-round operation, the savings become even more significant, and investing in a quality class A pump usually pays for itself within a few heating seasons through electricity savings alone, not to mention quieter and more reliable operation.

How to choose the correct installation length – 130 mm or 180 mm

For circulation pumps, the "installation" or "construction" length refers to the distance between the axes of the pump's two connection ports. This value is not a matter of choice based on output, but must exactly match the existing spacing of the connections in the boiler or piping – it is therefore a purely dimensional, not a performance, parameter.

The most reliable method for selecting a replacement is to remove the original pump and physically measure the distance between the centers of its two connection ports using calipers or a tape measure. If the pump has not yet been removed, the dimension can also be verified from the type designation on the label (manufacturers commonly state the length directly in the model designation, for example as "-130" or "-180" at the end of the type code).

For service work on ATTACK boilers, we always recommend stating the exact production (serial) number of the boiler before ordering – this allows unambiguous verification of which installation length and which exact pump type was factory-fitted in that particular boiler, as component suppliers may have changed during production series even within the same boiler power range.

The connection threads of both length variants are standardized to a 1½" internal thread with a union nut, so there is no difference between the 130 mm and 180 mm versions in terms of connecting to the piping itself – the only difference is the distance between the two ports.

Original part for 180 mm service ranges of ATTACK boilers

The Yonos PARA RS25/6 RKC pump is the 180 mm variant of the same product range as the OT130A (130 mm), intended for those ATTACK boiler models and service series that come factory-fitted with a longer connection installation length. Using the original part instead of a universal alternative is recommended especially in the following cases:

• in-warranty service, where the use of original or manufacturer-approved replacement parts is required,
• boilers with the pump connected to the control electronics (fault signaling, PWM speed control from the boiler board),
• situations where the operator wants maximum conformity with the boiler's original production documentation,
• repeated failures of a non-original replacement, where it is recommended to switch back to a proven OEM part.

As with the shorter variant, the connection thread here is also a standard 1½", so mechanical installation is identical to common circulation pumps of this category – only the installation length and the specific OEM design compatible with ATTACK boilers differ.

Technical parameters

• Installation (construction) length: 180 mm
• Energy class: A (EEI ≤ 0.20)
• Electrical input: 3 – 45 W, automatic regulation (auto-adapt)
• Maximum head: 6 m
• Maximum flow rate: up to 3.5 m³/h
• Connection: 1½" internal thread, union nut (RKC design)
• Medium temperature range: 2 – 110 °C
• Power supply: 230 V / 50 Hz, IP44 protection rating
• Pump manufacturer: WILO SE (Germany), supplied as an OEM part for ATTACK s.r.o.

How to read the circulation pump type label

The type label is attached directly to the body of the pump's electronic head and contains all the information needed to unambiguously identify the pump when ordering a replacement. Besides the factory type designation (e.g. RS 25/6, Yonos PARA RS25/6), you will also find the installation length there (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 no longer legible (for example after years of operation in a humid boiler room environment), the most reliable method is to directly measure the installation length with calipers, or to contact our customer service with the production number of the ATTACK boiler itself – from this we can determine which pump was factory-fitted in that particular boiler.

When is it time to replace the circulation pump

The circulation pump is a component that usually does not fail suddenly, but its performance and reliability gradually deteriorate with years of operation. A few symptoms to watch out for:

• Uneven heating – some radiators or circuits are noticeably cooler than others even when the thermostatic heads are fully open, which may indicate insufficient pump flow output.
• Increased noise – buzzing, squeaking, or knocking during operation that does not disappear even after thorough venting of the circuit, usually indicates worn bearings.
• Frequent tripping of the thermal fuse or outages – may indicate mechanical seizing of the rotor or an electrical fault in the motor winding.
• Visible leakage at joints or in the shaft area – over years of operation, the seal or gasket may wear out.
• High electricity consumption compared to declared values – an older non-regulated pump without class A 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.

Installation – practical procedure

Replacing or installing a circulation pump is not complicated in itself, but it requires following a few principles that affect the pump's lifespan as well as the trouble-free operation of the entire heating circuit:

1. Shutting down and draining the circuit. Before removing the old pump or installing the new one, close the ball/shut-off valves on both sides of the pump (if fitted) and drain the water from that section of the circuit to minimize medium leakage and contamination of the boiler room.
2. Checking the flow direction. There is an arrow on the pump body indicating the flow direction – the pump must be installed exactly in the direction of the heating water flow, otherwise it will not work efficiently or at all.
3. Orientation of the motor head. The electronic head (terminal box and control panel) of the pump must be oriented horizontally after installation, never facing downward – this prevents condensate or any possible water leakage from entering the electronics. On horizontal piping, the head is usually rotated to a side position.
4. New gaskets. Use new flat gaskets under the union nuts every time you replace the pump – worn original gaskets are the most common cause of microscopic leaks after servicing.
5. Filling and venting. After screwing in and tightening the connections, slowly fill the circuit with water with the shut-off valves open, and vent the system through the vent valves at the highest points of the system, as well as through any vent screw at the front of the pump rotor (if included in the design).
6. Checking tightness and function. After starting the boiler and the pump running up, check the tightness of both connections, the absence of unusual noise (buzzing may indicate air in the pump), and the correct function of the automatic power regulation when the thermal load changes.

Always leave the electrical connection to a qualified person (electrician or service technician) – the pump is connected to a 230 V mains supply, and in boiler applications it may be powered directly from the boiler's control electronics.

Maintenance and extending pump life

Electronically controlled circulation pumps of this category are virtually 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 their operating life:

• Quality of the heating water. Excessive sludge, rust, or air in the heating circuit is the most common cause of premature wear of the impeller and bearings of the wet-rotor motor. For older or recently piped systems, we recommend considering the installation of a dirt filter or sludge separator upstream of the pump.
• Regular visual inspection. Once per heating season, check the tightness of the connections, the absence of corrosion traces on the pump body, and unusual sound manifestations (buzzing, knocking) that may indicate air in the system or an early 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 briefly start it up occasionally to prevent the rotor from "seizing" due to deposits after prolonged inactivity – most modern pumps handle this automatically through a built-in permanent self-test.
• Frost protection. In unheated spaces (e.g. shut-down cottages, unheated technical rooms), in the event of frost risk it is necessary to either ensure the circuit is drained or use an antifreeze mixture with declared compatibility with the pump materials.

Safety warnings

Before any intervention on the pump, always disconnect the 230 V power supply and wait until the pump body has cooled down sufficiently – heating water can reach temperatures close to 90 °C and there is a risk of burns. Electrical connection may only be carried out by a person with appropriate electrotechnical 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 specified in the technical parameters – exceeding these limits may damage the pump and endanger operational safety.

Frequently Asked Questions

What does the designation RKC in the pump name mean?
RKC denotes a specific version of the connection/compact set of this OEM part, as fitted by the ATTACK boiler manufacturer at the factory in the 180 mm service ranges. It ensures direct conformity with the original part without the need for modifications.

Is this part interchangeable with the OT130A?
No, they have the same electronic and hydraulic parameters but a different installation length (180 mm versus 130 mm) and are therefore not interchangeable without modifying the piping.

How do I know if my ATTACK boiler needs this specific 180 mm OEM part?
By checking the boiler's production number with our customer service, or by directly measuring the installation length of the original pump before ordering.

Why is the price of the OEM part higher than that of the universal OT01B pump of the same length?
The price difference reflects the authenticity of the part, its direct conformity with the ATTACK boiler's production documentation, and possible compatibility with the boiler's control electronics, which a universal alternative may not fully guarantee.

Is the pump supplied with a connection cable to the boiler board?
The part is supplied as the pump itself with mounting accessories (nuts, gaskets). Any signal/power cable to the boiler board is usually kept original during a service replacement and simply reconnected to the new pump.

Does the pump itself need to be vented during installation, or is it enough to vent the circuit?
We recommend venting the entire affected section of the circuit through the vent valves; if the pump has its own vent screw at the front of the rotor, it can be used for additional venting directly within the pump body.

What is the expected lifespan of this type of pump under normal operation?
With correct installation, proper heating water quality (without excessive sludge and dirt), and normal operation during the heating season, the lifespan of electronically controlled circulation pumps of this category is typically in the tens of thousands of operating hours.

Is the part also suitable for cascade connection of multiple ATTACK boilers?
Yes, provided that the individual boilers in the cascade use the same factory-fitted type and installation length of the Yonos PARA RKC 180 mm pump, the part is also suitable for servicing cascade assemblies.

What should I do if I am not sure after ordering whether it is the correct part?
Contact our customer service with the boiler's production number before installation – we will gladly verify the type and installation length to avoid an unnecessary replacement after purchase.

Overview of related circulation pumps in the ATTACK range

You can also find alternatives to this original OEM part:

• ATTACK Pump WILO Yonos PARA RS25/6, 130 mm – an original OEM part of the same series, only with a shorter installation length for other ATTACK boiler service ranges.
• ATTACK Replacement part - pump RS 25/6-3-PR, 180 mm – a more economical non-original alternative of the same installation length, suitable outside of warranty service.
• ATTACK Heating circulation pump PR 25/6, 180 mm, class A – a universal pump of the same length also suitable for other boiler brands.

Summary

The ATTACK Pump Yonos PARA RS25/6 RKC, 180 mm is an original OEM replacement part for ATTACK boiler service ranges with a longer installation length. Choose it whenever you need to maintain full conformity with the boiler's original factory installation.

Warranty and support

We provide a 24-month warranty from the date of dispatch from the warehouse for this product. The warranty covers manufacturing and material defects, provided the installation and operating conditions specified in the manufacturer's enclosed manual are observed. If you have any questions about selecting, compatibility, or installing the pump, please do not hesitate to contact our customer service – we will be happy to help identify the correct type based on the production number of your ATTACK boiler or the parameters of your heating circuit.

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