Product detailed description

ATTACK Replacement Part - Pump RS 25/6, 130 mm

Replacement circulation pump RS 25/6 with an installation length of 130 mm, electronically controlled, energy class A. A compact and affordable replacement part suitable for service replacements on boilers and pipework with a shorter distance between connections, including selected ATTACK models.

Just like the 180 mm variant (OT01), this is primarily an economical service replacement intended for post-warranty replacements and modernization of older, unregulated pumps, not an exclusive OEM part tied to a specific boiler production line.

Why choose a class A circulation pump

The circulation pump is one of the heating system components with the longest operating time – it runs practically non-stop during the season, which is why its efficiency is crucial for the overall operating economy of the boiler. This pump achieves an EEI index ≤ 0.20, placing it among the most economical solutions on the market for domestic and smaller commercial heating circuits.

Electronic control with automatic power adaptation (so-called auto-adapt or proportional pressure) continuously monitors the current state of the circuit – closing of thermostatic heads, flow changes with zone control – and adjusts the impeller speed accordingly. As a result, the pump does not run needlessly "at full throttle" when the system does not require it, which directly translates into savings on your electricity bill.

Compared to a standard unregulated pump of an older generation (for example, a classic three-speed type with a power input of 40 – 90 W at the highest setting), this class A pump can consume, at the same output, only 3 – 20 W at the average operating point, representing a noticeable saving over an entire heating season without any compromise in heating comfort.

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 in the distribution pipework – it is therefore a purely dimensional, not a performance, parameter.

The most reliable procedure when choosing 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 recommend always stating the exact production (serial) number of the boiler before ordering – this makes it possible to clearly verify which installation length and which exact pump type was factory-fitted in that particular boiler, since component suppliers may have changed during production runs 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 in terms of the connection to the pipework itself there is no difference between the 130 mm and 180 mm versions – the only difference is the distance between the two ports.

Compact and affordable service replacement

The RS 25/6 in the 130 mm version is intended primarily for:

• post-warranty replacement of a faulty or unregulated pump with the same 130 mm installation length,
• modernizing an older installation to an electronically controlled class A solution with limited installation space,
• service work where price plays a decisive role while maintaining full functionality and energy class A,
• more compact boilers and manifolds with a shorter distance between connections, including some ATTACK models.

Unlike the -3-PR variant (OT01, 180 mm), this 130 mm RS 25/6 type is supplied in a basic version without an extended choice of operating curves, which is also reflected in its lower purchase price – hydraulically and energetically, however, both types remain very close to each other.

Technical parameters

• Installation length: 130 mm
• Energy class: A (EEI ≤ 0.20)
• Power input: 3 – 45 W, automatic control
• 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 rating

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 it when ordering a replacement. In addition to the manufacturer's 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 under 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 a humid boiler room environment), the most reliable option is to directly measure the installation length with calipers or 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 it is time to replace the circulation pump

The circulation pump is one of the components that usually does not fail suddenly, but whose performance and reliability gradually deteriorate with years of operation. Here are several symptoms to watch out for:

• Uneven heating – some radiators or circuits are noticeably colder than others, even with the thermostatic heads fully open, which may indicate insufficient pump delivery capacity.
• Increased noise – humming, squeaking or knocking during operation that does not disappear even after thoroughly bleeding the circuit usually indicates worn bearings.
• Frequent tripping of the thermal protection 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 – after years of operation, the seal or gasket may become worn.
• High electricity consumption compared to the declared values – an older unregulated 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 requires following a few principles that affect the pump's service life and 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 the leakage of medium and contamination of the boiler room.
2. Checking the flow direction. The pump body has an arrow 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. After installation, the pump's electronic head (terminal box and control panel) must be oriented horizontally, never facing downward – this prevents condensate or any water leakage from entering the electronics. On horizontal pipework, the head is usually rotated into a side position.
4. New gaskets. Use new flat gaskets under the union nuts with every pump replacement – worn original gaskets are the most common cause of microscopic leaks after servicing.
5. Filling and bleeding. After screwing and tightening the joints, slowly fill the circuit with water with the shut-off valves open and bleed the system through the bleed valves at the highest points of the system as well as through any bleed 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 (humming may indicate air in the pump) and the correct function of the automatic power control when the heat load changes.

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

Maintenance and extending the pump's service life

Electronically controlled circulation pumps in this category are practically maintenance-free – they contain no lubrication points or parts requiring regular servicing beyond a routine check. Nevertheless, a few simple habits will significantly extend their service life 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 of the impeller and bearings of the wet-rotor motor. For older or recently distributed 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 marks on the pump body, and any unusual sounds (humming, knocking) that may indicate air in the system or an incipient 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.
• Frost protection. In unheated spaces (e.g. closed-down cottages, unheated technical rooms), where there is a risk of frost, either ensure the circuit is drained or use an antifreeze mixture with declared compatibility with the pump's materials.

Safety notices

Before any intervention on the pump, always disconnect the 230 V power supply and wait until the pump body has sufficiently cooled – 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 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 operating safety.

Frequently asked questions

Is this part a full replacement for the OEM WILO Yonos PARA 130 mm (OT130A)?
Hydraulically and energetically, yes (same class A, head and flow rate), however it is an alternative, not an identical OEM part. For warranty service requiring the original part, we recommend the OT130A instead.

What is the difference compared to the 180 mm OT01 variant?
The main difference is in the installation length (130 mm compared to 180 mm) and in the fact that the OT01 (180 mm) additionally offers optional operating curves (-3 in the designation), whereas this 130 mm type comes in a basic version.

How exactly do I measure whether I need the 130 mm or 180 mm length?
Measure the distance between the centers of both connection ports of the original pump with calipers or a tape measure, or check the type designation on the label of the original pump, where the length is usually part of the code.

Is the pump suitable for a circuit with multiple zones controlled by thermostatic heads?
Yes, the electronic control automatically responds to flow changes caused by the closing of thermostatic heads and smoothly adjusts the output, preventing unnecessary noise in the fittings.

Is the pump supplied with installation accessories?
Yes, the package includes the union nuts and gaskets needed for standard installation on the 1½" thread.

What is the typical electricity consumption of this pump in normal operation?
Thanks to automatic control, the actual power input at the average operating point is usually in the range of a few watts up to a maximum of 45 W under the highest load, which is significantly less than with older unregulated pumps.

Can I adjust the pump's output setting myself without a service technician?
The basic operating mode setting can be made directly on the pump's control panel according to the enclosed instructions, however, if in doubt, we recommend calling in a heating technician, especially with more complex zone systems.

Is this part also suitable for other boiler brands, not just ATTACK?
Yes, it is a universal replacement part with a standard 1½" connection and a common 130 mm installation length, usable for most installations with the same connection spacing.

What should I do if the pump vibrates noisily after replacement?
Check that the union nuts are evenly tightened without stressing the pipework, that the circuit has been thoroughly bled, and that the pump has not been installed against the flow direction indicated by the arrow on the body.

Overview of related circulation pumps in the ATTACK range

When choosing a replacement pump with a 130 mm installation length, the ATTACK range offers several variants to choose from:

• ATTACK Pump WILO Yonos PARA RS25/6, 130 mm – original OEM part recommended for warranty service of ATTACK boilers.
• ATTACK Heating circulation pump 25/6, 130 mm, class A – universal pump also suitable for other boiler brands.
• ATTACK Replacement Part - Pump RS 25/6-3-PR, 180 mm – same product line, longer 180 mm variant with optional operating curves.

Summary

The ATTACK Replacement Part - Pump RS 25/6, 130 mm is a compact and affordable class A service replacement, suitable for installations with a shorter distance between connections, including selected ATTACK boiler models.

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 stated in the enclosed manufacturer's 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 the proof of purchase and, in case of servicing an ATTACK boiler, stating the type designation and production number of the boiler – this will speed up any warranty claims and future identification of replacement parts.