Radiator control set - what it includes and when it's worth buying a set

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Thermostatic valve set – what it contains and when it is worth buying a set

When a customer comes into a heating equipment store and says they need a "valve for the radiator", they are usually referring to just one visible part – the thermostatic head. In reality, a functional radiator regulation consists of several components that must be mutually compatible, correctly dimensioned and properly installed. This is why so-called regulation sets exist – complete packages where the manufacturer has assembled everything needed into one package. In this article, we will take a detailed look at what a regulation set contains, how the individual components work, when it is really worth buying a ready-made set and when it is more advantageous to choose components separately.

If you are looking for a deeper foundation on what types of valves exist and how to choose them correctly, we recommend reading the article How to choose the right radiator valve – type, connection and compatibility in our Knowledge Centre first. Here we will focus specifically on the issue of sets and their components.

What is a regulation set and what it consists of

A regulation set is a manufacturer-assembled set of components intended for hydraulic and thermostatic regulation of one radiator. Most often it is a combination of a thermostatic valve, a thermostatic head and a closing-regulating valve (so-called regulating valve on the return). Depending on the specific set, adapters, seals, caps, covers and other accessories may also be part of it.

The basic logic is simple: each radiator has two connections – the supply (hot water supply from the boiler) and the return (return of cooled water back to the boiler). A thermostatic valve with a head is installed on the supply, which regulates the amount of water flowing through it according to the room temperature. A closing or regulating valve is installed on the return, which is used to set the hydraulic balance of the entire system and allows the radiator to be shut off, for example, during repairs or replacement.

Thermostatic valve – the heart of regulation

A thermostatic valve is a valve with the possibility of connecting a thermostatic head. Inside it has a special seat and a pin (stem), which the head mechanically controls – it compresses or releases depending on the ambient temperature. It is important to correctly distinguish whether it is a single-regulation or double-regulation (pre-setting) valve.

Single-regulation valve allows only to turn on/off the flow (via the thermostat). It is suitable for older, hydraulically unbalanced systems where there is no interest in precise flow regulation.

Double-regulation (pre-setting) valve has, in addition to the thermostatic function, a mechanical pre-setting of the flow – by turning the adjusting screw, we limit the maximum flow through a specific radiator. This is key for hydraulic balancing of the system, i.e. for even distribution of heat between all radiators. If one radiator is right next to the boiler and another is at the end of a long pipe run, without pre-setting the first radiator will always be overheated and the last one cold. Hydraulic balancing is now a standard requirement for almost every central heating project.

A typical example of a pre-setting valve is thermostatic double-regulation valve – 1/2" × EK; corner type, which is mounted on the corner connection of the radiator (i.e. when the pipe comes out of the wall at a right angle to the radiator). What the dimensions 1/2" and EK mean is explained in more detail in the article Dimensions and threads of radiator valves – what do the markings 1/2", 3/4" and EK mean.

Thermostatic head – the brain of regulation

The thermostatic head is mounted on the valve body. It contains a temperature-sensitive element (most often filled with liquid or gas), which expands when heated and mechanically presses the valve pin – thus reducing the flow and slowing down the hot water. When the room cools down, the element contracts, the pin is released and the flow increases. The whole process takes place without electricity – purely mechanically.

Heads differ mainly in size, shape, temperature range and type of connection (most often Danfoss RA or manufacturer's own thread). In practice, it also depends a lot on where the head is placed – if it is under a windowsill or behind a curtain, a standard side head can overheat and measure incorrectly. In such cases, special remote temperature sensors or larger, more robust heads with better air circulation around the sensor are used.

From our range, for example, thermostatic head HPW large or thermostatic head large – lacquered are available, which is suitable where the visual appearance also matters (e.g. in living rooms with modern radiator design).

Closing/regulating valve on the return

The third basic component of the set is the valve on the return. It can be:

Simple closing valve – allows only full opening or closing (without flow regulation). Suitable for systems where the hydraulics are solved in another way (e.g. by regulating valves on the manifold).
Regulating (lockshield) valve – allows precise setting of the flow using a hidden adjusting screw (usually a key or screwdriver is needed for setting). Once set, the valve can be opened or closed by the user, but the pre-setting cannot be accidentally changed. This is standard in hydraulic balancing.
Closing valve with flow measurement – an advanced version with an integrated measuring plug (for connecting a differential pressure gauge), suitable for larger projects.

Additional components of the set – seals, adapters, caps

High-quality regulation sets also include accessories without which the installation would not be complete: flat seals or hemp/PTFE seals, adapters for connecting to a capillary tube or directly to the radiator outlet, caps for the valve handle of the return pipe, or possibly adapters for different types of connections. These may seem insignificant – but anyone who has ever searched for the right seal on a Sunday morning because water was leaking knows exactly what we mean.

Regulation sets HPW Set1 and HPW Set2 – what are the differences

On atria.sk you will find two specific sets: regulation set HPW Set1 and regulation set HPW Set2. Both are directly intended for standard panel and section radiators and are designed so that the customer receives a complete regulation system without any compromises in compatibility.

HPW Set1 is a basic set oriented towards simple installations: it includes a thermostatic valve, a thermostatic head and a shut-off valve on the return pipe. It is suitable where the system hydraulics are solved centrally (e.g. via regulating valves on the heating manifold) and only thermostatic regulation and the possibility of closing are required at the specific radiator.

HPW Set2 is an extended version – it adds a two-way regulating valve (pre-setting) to the basic trio, which allows hydraulic balancing directly at the valve for each radiator. This is the preferred solution for most standard apartment and single-family house systems, where the hydraulics are not solved by another component. If you have five radiators on one circuit in your house, without pre-setting the one closest to the boiler will always be hot and the one furthest away will barely be warm.

For quick orientation: if you are not sure which set is right for you, decide based on the layout of your heating system. If the project documentation is not available, a good heating technician can tell you during an inspection whether the system is hydraulically balanced centrally or not. If it is not clear – choose Set2, the inefficiency of pre-setting does not limit functionality in any way, you just leave it fully open.

When it is worth buying a set and when it is not

This is a question that customers often consider – and the correct answer depends on the specific situation.

Situations where a set clearly wins

New installation or complete reconstruction: If you are going to replace all the valves in your apartment or house (typically during reconstruction, boiler replacement or switching from district heating to your own boiler), buying sets for each radiator is more economical than buying components separately. The manufacturer guarantees mutual compatibility of all parts, you do not have to worry about whether the head fits the valve, and you also save time during installation.

You have no experience with heating technology: If you are unsure which valve, head and return valve go together – a set is the right choice for you. The manufacturer has already solved the entire compatibility issue for you.

You want hydraulic balancing without a designer: Two-way sets (such as HPW Set2) are designed so that the heating technician can set the pre-setting on site using simple tables (based on the length of the piping and the radiator output) without the need to prepare a hydraulic design. For single-family homes with simpler systems, this is a sufficient solution.

Service replacement with the same type of connection: If you know that your radiator has a 1/2" corner connection and the original set has reached the end of its life (a leaking valve, a non-functional head), simply buy an identical set – and you are sure everything will fit. More about types of connections can be found in the article Corner vs. straight valve – how to determine which type you need.

Situations where it is worth buying components separately

Replacement of only one component: If your valve and return valve are working fine, but only the thermostatic head has failed – there is no reason to buy a whole set. It is enough to buy just the head that fits the original valve (of course, compatible in terms of thread and type of mounting).

Special requirements for design or function: Do you want chrome heads for the bathroom and white ones for the children's room on the same valves? Or do you need a programmable electronic head for certain rooms? In such cases, you combine valves from one set and heads from another range – the condition is thread compatibility.

Large projects with a hydraulic design: In apartment buildings, commercial spaces or larger single-family homes, a specialized designer prepares a hydraulic design, which prescribes specific pre-settings for each circuit and radiator. In this case, valves and heads are purchased separately according to the design – sets do not add any value in this case and can even be unnecessarily expensive.

Corner or straight valve – the basic choice when selecting a set

Before you choose a set, you need to know what type of connection your radiator has. This is the most common reason for ordering errors. There are three basic configurations:

Corner (angle) valve: The pipe comes out of the wall horizontally (or from the floor vertically) and feeds the radiator from the side or from below. The valve makes a 90° angle. This is by far the most common type in panel buildings and new constructions.
Straight (axial) valve: The pipe and the radiator connection are on the same straight axis. It is used when the pipe comes directly from the wall in the direction of the valve axis (typical for older installations).
Axial valve (central bottom connection): Both pipes (supply and return) are led under the radiator and feed it via a central bottom connection. Modern bathroom radiators or design panel radiators are connected in this way.

Control sets HPW Set1 and HPW Set2 are designed for corner connection, which is dominant in Slovak households. If you have a different configuration, it needs to be verified before ordering.

How to correctly dimension a control set – dimensions and threads

The most important dimension when selecting is the nominal diameter of the valve thread. For most standard apartment and house radiators, the following applies:

DN10 / 1/2": Standard apartment radiators, panel radiators with side connection. This is by far the most common case.
DN15 / 3/4": Larger radiators, bathroom manifolds, cast iron section radiators with higher output.
EK: Designation for an extended European cone (Eurokónus) thread, which is compatible with side connection pipe fittings on the radiator. A valve marked "×EK" has an Eurokónus thread on the radiator side (without sealing, sealed by metal-to-metal contact) and a standard pipe thread on the pipe side.

In practice, before purchasing, check the following:

Pipe diameter (1/2" or 3/4" – usually 1/2" for standard panel radiators)
Type of connection on the radiator (EK or standard internal thread)
Direction of the pipe inlet (corner or straight valve)

If you are still unsure, the article Dimensions and threads of radiator valves – what do the markings 1/2", 3/4", and EK mean? in this Knowledge Center will help you.

Installation of the control set – what to pay attention to

Installing a control set is not rocket science, but it does require at least basic skills and respect for a few rules. A detailed guide can be found in the article Installation of a thermostatic valve on a radiator – step-by-step procedure, here we will limit ourselves to the most important practical warnings:

Drain the system or shut off the section: Before removing old valves, you must stop the flow. In panel buildings, this usually means closing the riser shut-off valve (usually in the basement or in the riser shaft). In houses, it is sufficient to turn off the pump and close the shut-off valve before the respective circuit. Never remove a valve under pressure – water spreads much faster than you think.

Check the condition of the riser and connections: During the renovation of old panel buildings with steel pipes, it is not uncommon for the old threaded connection to break off when unscrewing the old valve due to corrosion. Having a pipe wrench and spare fittings on hand is a wise precaution.

Do not switch the head to "closed" before filling: When filling the system, keep the thermostatic head set to maximum (position "5" or "open") – otherwise water will not reach the radiator. The height setting and calibration are addressed only after filling and bleeding. More details can be found in the article Setting and calibration of a thermostatic head – how to correctly set the temperature.

Use the correct seals: Always use sealing on the threads – either hemp rope with paste or Teflon tape. Do not use sealing on EK (Eurokónus) connections, as they are sealed by metal-to-metal contact. Excessive greasing of the EK connection with paste can actually prevent proper sealing.

Hydraulic balancing – why it is important and how to set it

We have mentioned hydraulic balancing several times, but it deserves its own subsection, as it is a topic that many DIY enthusiasts and even experienced heating technicians underestimate.

A heating system is a hydraulic circuit. Water always finds the path of least resistance – that is, it flows preferentially through shorter branches with lower pressure. Result: radiators near the boiler are hot, distant ones are barely warm. Thermostatic heads do help regulate room temperatures, but without hydraulic balancing, they operate under sub-optimal conditions and the system is energy inefficient.

A preset (two-way) valve allows you to set the maximum flow for each radiator individually. The setting is usually expressed as a number from 1 to 8 (or a similar scale), with each number corresponding to a specific flow rate in liters per hour. Correct presetting is calculated based on the radiator output, system temperature drop, and available differential pressure.

For a simple apartment system with 3–6 radiators and not too long piping, an approximate setting according to manufacturer tables is sufficient. For more complex systems (larger houses, multiple circuits, mixing units), we recommend entrusting hydraulic balancing to a professional with measuring equipment.

Most common mistakes when selecting and installing control sets

From practice, we know that we repeatedly encounter the same mistakes:

Purchasing a straight valve instead of a corner one (and vice versa): The customer does not check the direction of the pipe inlet and the valve simply does not fit into the installation. Always check whether the pipe comes from the wall (corner) or in the extension of the axis (straight).
Incompatible head: Not every head fits every valve. Most European manufacturers use the M30×1.5 thread, but there are exceptions (e.g., Danfoss RA with a special locking ring). Always verify compatibility – it is guaranteed by the manufacturer in sets.
Forgetting the return valve: Many only address the thermostatic valve with a head and leave the return valve old. After some time, the old one gets stuck or starts dripping and the system has to be drained again. If you are replacing the supply, always replace the return as well.
Over-tightening the thread during installation: Especially with brass valve bodies, there is a risk that the customer will break the thread while tightening. Rule of thumb: tighten by hand until it stops + maximum 1.5–2 turns with a wrench. More is not better.
Forgetting to bleed the radiator after filling: After replacing valves and filling the system, there is air in the radiator. If the radiator does not heat or only heats on one side, it is likely air. Loosen the bleed valve (usually at the top corner of the radiator) until water flows out.

Cost of sets vs. individual components – a practical calculation

Let's compare real costs for a typical situation: replacing regulation on five radiators in an apartment.

When purchasing components separately (thermostatic valve + head + check valve + seals for each radiator), you encounter several hidden costs: time spent selecting, risk of incompatibility, and possible need to buy missing seals or adapters. On average, this can be 15-25% more expensive (in time and money) than buying tested sets.

A set from a trusted manufacturer is tested as a whole, has a unified warranty period, and the customer has a clear point of contact for complaints. This is a benefit that is hard to quantify, but it has real value in practice.

FAQ – most frequently asked questions about regulation kits

Can I use a thermostatic head from another set (another manufacturer) on a valve from HPW sets?

It depends on the compatibility of the thread and the mounting method. Most European thermostatic heads today use the standard M30×1,5 thread – if both products use it, they will fit physically. However, the set manufacturer guarantees proper function only when used with their own head. In practice, mixing components from different manufacturers is common, but if there is an issue with functionality (e.g., incorrect temperature characteristics or needle pressure), it is harder to determine who is at fault. If you are unsure, use components from one set or consult your supplier.

Is it necessary to replace the check valve as well, or is it enough to replace only the thermostatic valve and head?

It is not always necessary, but we recommend replacing both valves at the same time whenever the system is drained. The check valve is stressed just like the supply – it ages, corrodes, and its seat wears out. If you are replacing the supply valve due to dripping or a faulty head, it is very likely that the return will also start dripping in 1-2 years. Replacing both at once saves time and avoids the cost of draining the system again.

How can I determine what type of thread and valve direction I need if I am not an expert?

Look at where the pipe comes from to the radiator. If it comes from the wall and bends toward the side of the radiator (forming an angle of about 90°), you need an angled valve. If the pipe and radiator connection are in a straight line, you need a straight valve. You can estimate the pipe diameter by hand – common copper pipes in apartments have a diameter of 15 mm (corresponding to a 1/2" valve). A knowledgeable salesperson can verify these parameters during a 5-minute inspection. For more inspiration, see the article Angled vs. straight valve – how to determine which type you need.

Can I install a regulation kit myself, or should I call a heating technician?

For a skilled DIY enthusiast with basic plumbing skills, installing a regulation kit on a standard panel radiator is feasible. The condition is the ability to shut off the water supply to the riser or circuit and to properly seal threaded connections. If you have any doubts about the condition of the pipes, old corroded joints, or a major renovation, we recommend hiring a professional. Slovak law does not require professional certification for replacing valves during routine maintenance (unlike gas or electricity), but in an apartment building, always check the building manager's rules. More detailed information can be found in the article Maintenance and servicing of radiator valves – what I can do myself and when to call a professional.

What to do if the thermostatic head does not respond after installation or the radiator does not heat?

First step: check that the head is properly mounted on the valve and locked (clicked in). Second step: set the head to maximum and wait a few minutes – the valve needle may be stuck in position. If it still does not heat, check the radiator for air. If it still does not help after bleeding, try temporarily removing the head and manually pressing the valve needle – if the radiator heats up, the problem is in the head (likely a stuck element). More scenarios are covered in the article Common problems with radiator valves – dripping, stuck valve, head does not respond.

Is it worth switching to electronic thermostatic heads during renovation?

If you plan a smart home or at least basic programmable regulation (e.g., night setback or schedule-based control), electronic heads bring real added value and the return on energy savings can be 2-4 years. However, be careful – electronic heads must be compatible with the type of valve (specifically with the needle lift diameter and thread). Not every electronic head works with every valve body. Always verify this compatibility with your seller or in the valve documentation before purchase.

Conclusion – regulation kit as the basis for efficient heating

A regulation kit on a radiator is not just a package of valves. It is the foundation for the entire heating system to work as it should – efficiently, evenly, and without unnecessary energy losses. A properly selected and installed kit with a preset (dual-regulation) valve body, a quality thermostatic head, and a regulation valve on the return can reduce heat consumption by 10-20% compared to an unbalanced system without proper thermostatic regulation.

For most Slovak households – apartments in panel buildings and single-family homes – we recommend choosing complete kits instead of buying components separately. You will save time, avoid compatibility issues, and be sure that everything fits together properly. If you are looking for specific products, see the HPW Set1 regulation kit for simpler installations or the HPW Set2 regulation kit with a dual-regulation valve body for full hydraulic balancing. The entire range of radiator valves, including individual components, can be found in the appropriate category of our online store.

Do you have a question about this topic?

Not sure what to choose or dealing with a specific situation in your home? Write to us – we are happy to help.