How to choose the right pump accessories – what to pay attention to
Pump Accessories – Why the Choice Is More Important Than It Seems
When a customer selects a pump – whether it's a circulation pump for the heating system, a submersible pump for a well, or a sewage pump for basement water removal – they usually focus on the performance, noise level, and price of the machine itself. Accessories are often just "thrown into the bag" as some kind of secondary purchase: a few fittings, a hose clamp, some coupling. And that's where the problems begin. From experience, I know that most leaks, vibrations, premature failures, and complaints are rooted precisely in incorrectly selected, cheap, or underestimated accessories. This article will help you understand what all belongs to the pump accessories, how to choose them correctly, and what to really pay attention to – not generally, but with specific numbers, types, and practical scenarios.
What All Belongs to "Pump Accessories"
Pump accessories are a rather broad category. To understand it, it is useful to divide it into logical groups by function:
- Connecting and fastening elements – hose clamps, rope clamps, flanges, unions, reducers
- Seals and sealing materials – O-rings, flat gaskets, Teflon tape, hemp fiber, liquid sealants
- Protective and regulating elements – check valves, shut-off valves, filters, membrane expansion vessels
- Mechanical support and mounting components – brackets, hangers, shims, anti-vibration pads, anchoring screws
- Electrical accessories – float switches, pressure switches, cable glands, pass-through fittings
- Hose and pipe connections – flexible hoses, compensators, transitions between different diameters
Each of these groups has its own selection criteria. A mistake is to approach them uniformly – what works for a sewage pump in a garden pond may fail for a circulation pump in a closed heating circuit with a temperature of 80 °C and a pressure of 3 bar.
First Step: Determine the Parameters of Your Pump and System
Before you buy anything in terms of accessories, you need to know a few basic parameters. This is not a formality – these are values from which the entire selection depends:
- Connection diameter (DN) – typically DN 25 (1"), DN 32 (1¼"), DN 40 (1½") or DN 50 (2") for home systems. Circulation pumps in radiator heating are most often DN 25 or DN 32.
- Working pressure (bar) – home heating standard 1.5–3 bar, well pumps 3–10 bar, industrial pumps up to over 16 bar
- Maximum working temperature (°C) – up to 110 °C for heating systems, 20–25 °C for cold water, 60–80 °C for hot domestic water
- Type of medium – clean water, water with corrosion inhibitors (in boiler circuits), aggressive water from wells, sewage water for sewage pumps
- Type of installation – vertical, horizontal, submersible, outdoor or indoor mounting
- Type of thread – external (AG) or internal (IG), metric (M) or pipe (G/BSP)
These parameters are not optional – they are essential. When a customer comes to me saying that they "need some fitting for the pump," I always ask exactly these things. Without them, the selection is random and the risk of incompatibility is high. We will deal with this topic in more detail in the article What Diameter and Type of Connecting Material Do I Need for My Pump in the Knowledge Center.
Material of the Accessories – the Most Important Decision Factor
The material from which the accessories are made directly determines their lifespan, resistance to corrosion, and suitability for a given system. In practice, we encounter the following materials:
Cast iron and gray cast iron
A classic material for fittings and valves in heating. Durable, rigid, cheap – but prone to corrosion when in contact with moist air or when temperatures fluctuate. It works well in closed heating circuits if the system is properly filled and treated with inhibitors. It is not suitable for outdoor installations or in environments with high humidity.
Brass
A very common material for threaded fittings, valves, and unions. It is easy to process, resistant to corrosion, and compatible with most sealing materials. Note: some brasses are sensitive to selective corrosion (dezincification) in soft or aggressive water. For cold drinking water, always request brass marked "DZR" (dezincification resistant).
Stainless steel (stainless)
For the most demanding applications – corrosive environments, outdoor installations, water with high chloride content. Significantly more expensive, but with several times longer lifespan. Typical use: rope clamps for securing well pump pipes, flanges in aggressive environments, clamps on hoses for pool cleaning. An example of a quality product in this category is the stainless steel rope clamp, which is used for fixing the discharge pipe of submersible pumps – in this case, stainless steel is practically a necessity, because the galvanized alternative in the wet environment of the well would last significantly shorter.
Zinc-coated steel
A compromise between cost and durability. The zinc coating protects the steel from corrosion, but only as long as it remains undamaged. Any mechanical damage (scratches during installation, threading) will expose the steel and corrosion will start quickly. Suitable for indoor installations where condensation is not present and regular inspection and maintenance are expected. A comparison of stainless steel and zinc-coated fittings can be found in the article Stainless steel vs. zinc-coated fittings for pumps – which is better.
Plastic (PP, PVC, PE)
Lightweight, chemically resistant, and inexpensive. Not suitable for hot media above 60 °C (depending on the type of plastic) or for mechanically stressed connections. Ideal for cold garden systems, rainwater drainage, or pool pumps. PP-R pipes and fittings can also handle hot water, but must not be exposed to UV radiation without protection.
Connecting elements – hose clamps and cable clamps
Hose clamps and cable clamps may seem like trivial components, but from experience I know that many problems arise precisely from them. A classic threaded hose clamp made of zinc-coated steel may be an attractive choice at a price of just a few cents, but when in long-term contact with moisture, sludge, or well water, it will rust and stop performing its function long before you notice it.
For pumps where the hose or pipe is regularly submerged or located in a humid environment, the right choice is a stainless steel cable clamp. The cable construction (a spiral cable wrapped around the pipe) ensures even distribution of force around the entire circumference, whereas a standard hose clamp only applies pressure at one point. This means better sealing and a lower risk of damaging a soft hose. Specifically for submersible well pumps, a stainless steel cable clamp is practically the standard – a steel cable with a stainless steel clamp will withstand years in the humid environment of a well without signs of corrosion.
When choosing hose clamps, pay attention to:
- Range of diameter – the clamp must cover the outer diameter of the hose. A clamp that is too large cannot be tightened sufficiently, and one that is too small will not fit at all.
- Band width – a wider band (12–16 mm) distributes force better and is suitable for stronger hoses or higher pressure. A narrow band (8–9 mm) can cut into the hose.
- Material of the screw – even if the band is stainless steel, a cheap zinc-coated screw can be a weak link. Look for fully stainless steel clamps (A2 or A4).
- Perforated vs. smooth band – a perforated band holds better on smooth hoses, while a smooth band is more durable under abrasive conditions.
Seals – choosing the right one according to temperature and medium
A seal is the cheapest component in the system and the most common cause of leaks. When choosing a seal, a simple rule applies: it must be compatible with the medium and the temperature range. Here is an overview:
| Type of seal | Max. temperature | Suitable media | Not suitable for |
|---|---|---|---|
| EPDM (rubber) | up to 150 °C | Water, steam, heating | Oils, gasoline, hydrocarbons |
| NBR (Nitrile) | up to 100 °C | Oils, fuel, air | Hot water above 80 °C, ozone |
| PTFE (teflon) | up to 260 °C | Almost all media | Dynamic applications (not for hoses) |
| Silicone | up to 200 °C | Food, pharmaceuticals, steam | Oils, concentrated steam |
| Flat rubber (CR) | up to 90 °C | Cold water, garden systems | Heating, aggressive chemicals |
A very common mistake in practice: the customer installs a standard rubber gasket (CR) in the connection of a circulation pump in the heating system. It works for several months, then the rubber softens, compresses and stops sealing. The correct choice is an EPDM gasket, which easily handles temperatures up to 150 °C. A similar topic is addressed in the article Common faults and water leaks in pump accessories – causes and solutions in the Knowledge Centre.
Protective elements – check valves, filters and expansion vessels
These components are indispensable in heating and pump systems, but if incorrectly selected, they can reduce the performance of the entire system or even cause its failure.
Check valves
They protect the pump from reverse flow of the medium when the pump is not in operation. In practice, I often ask customers whether their pump has a built-in check valve or not. Many modern circulation pumps already have one. If you add an external check valve to it, you may unnecessarily increase the hydraulic resistance of the system. On the other hand, for submersible pumps in a well, an external check valve on the discharge pipe is almost always necessary – it prevents the pressure tank from emptying after the pump is turned off.
Check valves are produced as threaded (compact, easy to install), flanged (for larger diameters), or with a spring (also for horizontal mounting, where gravity is not sufficient). For domestic heating, a threaded valve DN 25–40 with a spring closure is sufficient.
Filters and strainer baskets
Impurities in the system are one of the main causes of premature pump wear. A Y-filter (angled filter) before the pump captures mechanical impurities and extends the life of the mechanical seal and impeller. Filter mesh size: for circulation pumps 0.5–1 mm, for more sensitive systems (condensing boilers, heat pumps) 0.2–0.5 mm. The filter must be easily accessible for cleaning – this is often underestimated during installation.
Expansion vessels
A diaphragm expansion vessel compensates for changes in water volume when heated. Without it, the pressure in a closed heating system would multiply several times when heated from 10 °C to 80 °C – the safety valve would open repeatedly, the system would lose water and air. The size of the vessel is calculated according to the volume of water in the system and the temperature range – a rough orientation: 1/10 of the water volume in the system. For a house with 100 litres in the system, at least a 10-litre vessel is needed, and with a higher temperature range, preferably 18–24 litres.
Mounting accessories – brackets, shims, anchors
Customers most often deal with these accessories at the last minute, when they already have the pump installed and realize that the pipe is vibrating, sagging or they don’t know where to hang it. Prevention is always better.
For circulation pumps in the boiler room, it is important that the pipe is mechanically supported outside the pump itself. The pump must not be the only load-bearing element of a heavy pipe – this causes vibrations transferred to the pump body and premature bearing wear. Use pipe clamps or brackets every 1–1.5 metres for horizontal piping.
Anti-vibration rubber or composite shims under the pump can significantly reduce noise. This is one of the cheapest modifications with an immediate effect – customers who complain about a noisy circulation pump are often surprised how effective the anti-vibration shims are. A detailed step-by-step installation procedure can be found in the article Mounting accessories for circulation pumps step by step in the Knowledge Centre.
Choosing Accessories According to Pump Type – Practical Scenarios
Different types of pumps have different requirements for accessories. A summary of the most common scenarios from practice:
Circulation Pump in a Heating Circuit
Medium temperature: 60–85 °C, pressure: 1–3 bar, closed system. Accessories must withstand long-term thermal stress and work with inhibitors. You need: threaded unions with EPDM sealing (G1" – G1½"), ball valves before and after the pump (allowing replacement without draining the entire system), Y-filter on the suction side, expansion tank, safety valve. If it's a new build, also consider a magnetic descaler before the filter – a circulation pump clogged with sludge and magnetite is one of the most common causes of noise and malfunctions.
Submersible Well Pump
Wet environment, contact with groundwater, mechanical stress on cables and piping. Accessories: stainless steel cable clamp to secure the discharge pipe in the borehole, stainless steel flanges or hose clamps, pressure tank (membrane tank), pressure switch, Y-filter after the pump, check valve. The cable leading into the borehole must be secured with cable clamps to prevent the insulation from being damaged by the borehole walls. For more on choosing accessories according to pump type, see the article Choosing Accessories According to Pump Type – Circulation, Borehole, and Sewage Pumps.
Sewage Pump
Aggressive medium, mechanical impurities, mostly temporary use. Key points: durable discharge hose (min. 20 bar for pressure sewage pumps), stainless steel or surface-treated hose clamps, float switch with stainless steel weight, extension cable resistant to moisture (IP67+). Membrane tanks and fine filters are not used with sewage pumps – they would catch solid particles and clog immediately.
Thread Compatibility – the Most Common Source of Customer Problems
Threads are the topic where customers most often make mistakes. In pump accessories, you will encounter two main standards:
- BSP/G (Whitworth, pipe thread) – the standard in European heating and hydraulics. Designation: G1", G1¼", G1½", G2". The conical variant (R/Rp) is sealed by the thread itself, while the cylindrical variant (G) requires a face seal.
- Metric thread (M) – used for screws, anchors, flanges, and mounting parts. Designation: M8, M10, M12...
Combining G thread with metric thread is definitely non-functional – the pitch and thread profile are different. A conical thread (R) with a cylindrical one (G) may work for a short time, but it is not a correct combination and may leak under higher pressure. Always check the type of thread on the pump before purchasing accessories – most manufacturers list this in the technical documentation as "Rp 1"" or "G 1¼"". We will elaborate on this topic in the article What Diameter and Type of Connecting Material Do I Need for My Pump.
Corrosion and Long-Term Reliability – What Affects the Lifespan of Accessories
In heating systems, the most common causes of corrosion in accessories are: dissolved oxygen in water, low pH (acidic pH releases metal ions), chlorides in soft tap water, and galvanic corrosion when different metals come into contact. Galvanic corrosion occurs, for example, when you connect a copper pipe directly to a zinc fitting – an electrochemical cell forms between them and the zinc dissolves.
Solutions: always use dielectric couplings between different metals, keep the pH of the system water between 8.0–9.5 (mildly alkaline), add corrosion inhibitors annually, and in hard water, install a softening filter or a polyphosphate doser. We will elaborate on the topic of corrosion prevention in the article How to Prevent Corrosion and Damage to Pump Accessories in Heating Systems.
From practice: a customer had a circulation pump installed a few years ago with galvanized unions and brass fittings. The water in the system was soft and acidic (pH 6.8). After six years, the galvanized parts were completely rusted, and the threads could not even be unscrewed. The brass parts were in good condition. The cost of replacement was several times higher than it would have been to use brass or stainless steel accessories from the start.
Practical Checklist Before Purchasing Accessories
To conclude this section, I present a checklist I recommend to every customer before ordering accessories for a pump:
- ✔ Do I know the connection size of the pump (DN and thread type – G or metric)?
- ✔ Do I know the maximum operating temperature of the medium?
- ✔ Do I know the maximum operating pressure of the system?
- ✔ Do I know what medium is being pumped (clean water, water with chemicals, sewage)?
- ✔ Is the installation indoor or outdoor, wet or dry?
- ✔ Do I have a safety valve and expansion device ready (for closed systems)?
- ✔ Is the planned accessory made from compatible materials (galvanic compatibility)?
- ✔ Are the seals properly dimensioned for the given temperatures and medium?
- ✔ Is access to the filter and safety valve freely accessible for service?
Most Frequently Asked Questions (FAQ)
What is the difference between a hose clamp and a cable clamp – when to use which?
A hose clamp is a simple steel band with a screw closure. It is suitable for low pressure and dry indoor environments – for example, securing a flexible hose on a garden pump in dry conditions. A cable clamp is structurally more robust, distributes force more evenly around the hose, and is made of corrosion-resistant materials. For outdoor use, wet environments (well, pool), and higher pressure, we recommend stainless steel cable clamps – this is a more durable and safer solution.
Can I use the same accessories for heating and for drinking water?
Not always. Accessories for heating may not be certified for contact with drinking water. For example, some brasses used in hot water systems do not have WRAS or KTW/W270 certification. If you install accessories in a drinking water system, look for products with an explicit declaration of safety for drinking water and the appropriate certification. This is not necessary for heating, but it is essential for drinking water.
How do I recognize that a seal is beginning to fail – and what should I do about it?
The first signs are usually visual: a damp spot, a white calcified coating around the joint (dried water scale from a leak), or a regular pressure drop in the system without an obvious cause. If you see these signs, replace the seal as soon as possible – a leak does not stop on its own, it only gets worse. Before replacement, drain or isolate the section of the system, clean the sealing seat, and use the correct type of seal according to temperature and medium.
Do I have to replace the entire set of accessories when replacing the pump, or is the pump alone enough?
It depends on the condition of the existing accessories and how long they have been in use. If the unions, valves, and filter are in good condition and compatible with the new pump, it is not necessary to replace them. However, always replace the seals in the unions – it is cheap and unnecessary to risk a leak. If the accessories are over 10 years old, we recommend replacing at least the unions and filter – it will save you from later problems with a clogged filter or a broken old union during service.
What should I do if I am unsure about the size or type of accessory?
The most reliable approach: find the technical data sheet of your pump (usually on the manufacturer's website or in the attached documentation) and check the connection dimensions. If you don't have documentation, measure the outer diameter of the existing pipe with a caliper – for threaded connections, the outer diameter is always larger than the nominal diameter (DN25 has an outer diameter of 33.7 mm, DN32 has 42.4 mm, etc.). Alternatively, bring an existing fitting to the seller – they can usually identify the type and size immediately.
Is more expensive accessories always better?
Not automatically, but cheap accessories from unknown sources carry higher risks. The difference between a certified fitting from a reputable manufacturer and an unbranded fitting for a fraction of the price is not just in marketing – it is in the thread precision, wall thickness, alloy quality, and consistency. A single failure of a cheap fitting in a heating system can cause damage worth thousands of euros. We recommend investing in proven brands at least for critical components (unions, valves, safety valve). For less stressed areas, you can opt for a more cost-friendly alternative.
Conclusion – Accessories Are Not a "Secondary Purchase"
Accessories for pumps form the foundation of the entire system – without properly selected and installed accessories, even the best pump will not operate reliably or for long. Choosing accessories is worth approaching systematically: first the system parameters, then the suitable material, and finally the specific components. Always consider temperature, pressure, medium, and installation environment. An investment in quality accessories pays off in lower repair costs, longer system lifespan, and peace of mind that your heating or water supply system operates without surprises.
An overview of all available components can be found in the Pump Accessories category on atria.sk. If you are dealing with a specific installation, we also recommend reading other articles in the Knowledge Center – for example, How to Properly Seal and Secure the Pump Pipe – Cable Clamps and Couplings, Maintenance and Inspection of Pump Accessories – How to Extend Lifespan, or Common Questions About Pump Accessories for Heating and Water, where you will find answers to further specific situations.
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.