How to choose a distributor cabinet - dimensions and placement
Why not underestimate the selection of the distributor box
The distributor box is one of those elements of the heating system that the investor usually selects at the last minute - and this is a mistake that is responsible for a large portion of complaints and additional construction modifications that we encounter in practice. The distributor with its accessories needs to be installed somewhere already during the rough construction or during the realization of partitions, while the distributor itself is often purchased and installed just before the floor is poured. If the dimensions of the box do not match the actual selected distributor, the number of circuits and the way of connection, it ends either with cutting the box cladding, protruding doors that cannot be closed, or on the contrary, an unnecessarily large hole in the partition that needs to be additionally brickwork.
In this article, we will look at how to correctly choose the dimensions of the distributor box (height, width and depth), where to place it in the layout of the house or apartment, what are the differences between the wall-mounted and recessed (built-in) versions, and what to pay attention to when combining with step insulation and floor composition. If you are also solving the selection of the distributor itself, the number of circuits or the type of regulation, we recommend supplementing the information also from the articles How to choose a distributor for floor heating and How many circuits and outlets do I need on the distributor - this text focuses exclusively on the box and its placement.
Wall-mounted vs. recessed (built-in) box - basic decision
The first question to answer is the type of installation of the box. In practice, there are two basic solutions and the choice between them affects almost everything else - from the dimensions of the masonry recess to the way of routing the pipes.
Wall-mounted box
The wall-mounted box is mounted on the surface of the wall, typically in a technical room, shaft, garage or in a space where aesthetics give way to functionality. The advantage is the simple installation without interference with the masonry - it is sufficient to anchor the box to the wall using wall anchors and connect the pipes from below or from the side. The disadvantage is that the box protrudes into the space by approximately 12-13 cm, which can be a problem in narrow corridors or shafts. A typical example is, for example, Wall-mounted distributor box N-MAX 1 - 450mm for smaller distributors with up to 6-7 circuits, or a larger Wall-mounted distributor box N-MAX 5 - 1200mm for more extensive systems with multiple distributors next to each other, typically in larger apartments, family houses with multiple floors or when solving multiple zones simultaneously.
Recessed (built-in) box
The recessed box is built directly into a recess in a masonry or gypsum board partition so that only the frame with the doors remains visible after completion, aligned with the surface of the wall or slightly protruding by 2-4 cm. This solution is used much more in living spaces - in the entrance hall, corridor, bedroom or wardrobe, where the investor does not want a technical element to spoil the interior look. The disadvantage is the need for precise planning already in the rough construction phase, because the recess must be built or created in the partition before it is covered with gypsum board. A representative of this category is, for example, Wall-mounted distributor box N-KLASIK 2 - 535mm, which is often chosen in practice as a universal, cost-effective variant for apartment cores and family houses.
Note on terminology - despite the fact that the word "wall-mounted" appears several times in the product name, in the product range you will also find versions intended for recessing into the partition (with a frame for embedding). When ordering, therefore, always check the product parameters to see whether it is a version for surface mounting, or a version with a frame for recessing - this will save you from unnecessary complaints.
How to correctly measure the dimensions of the box - height, width, depth
The dimensions of the box are not determined by a rough estimate "at a glance", but by calculation according to the specific distributor that will be placed in the box. Here is the procedure we use in design:
Width of the box
The width of the box must accommodate the distributor itself (or a pair of distributors - return and supply, which are usually connected by consoles and form one unit) and at the same time offer sufficient reserve on the sides for handling with a key during regulation of flow meters or during bleeding. In practice, a reserve of at least 10-12 cm is calculated on the overall width above the dimensions of the distributor itself - so if the distributor with 8 circuits has a width of approximately 55 cm, you need to calculate with a box at least 65-70 cm wide. When installing two distributors next to each other (for example, for separate zones on two floors), this reserve naturally increases and the widest models, such as the mentioned 1200 mm box, are sought.
Height of the box
The height of the box mainly affects how much space you need above and below the distributor for connecting supply pipes, ball valves, and possibly also for placing accessories such as a mixing unit, circulation pump or controller. A common practice in floor heating in family houses is a box height of 650-900 mm when mounted low on the floor (lower edge about 10-15 cm above the floor), which allows convenient connection of the supply lines from below from a shaft in the floor. When mounting the box higher on the wall (typically in a technical room together with connection to the boiler distribution), the height is chosen according to how many additional components can fit into the box.
Depth of the box
Depth is a parameter that is most often underestimated. It must take into account not only the depth of the distributor itself with mounted flow meters and servomotors (which usually protrude forward by another 4-6 cm), but also the pipe bend radius that is led into the distributor from the floor. For a recessed box, a typical depth of the recess is 110-130 mm, for a wall-mounted box mounted on the surface of the wall, a total protrusion of about 120-150 mm from the surface of the wall is calculated. If you plan to use a distributor with thermostatic heads or servomotors controlled by a thermostat, add at least 5 cm extra to the depth so that the box doors do not hit the heads when closing.
Practical example from implementation
In a typical family house with 6 heating circuits on one floor, we usually choose a distributor with 6-8 outlets in a width of 40-55 cm. For such a distributor, a box with an internal width of about 45-60 cm and a height of 65-70 cm is most often installed in practice - that is exactly the dimensional category that the already mentioned Wall-mounted distributor box N-MAX 1 - 450mm falls into. In larger houses with 10-16 circuits divided into two zones (for example, ground floor and upper floor solved from one technical location), boxes with an internal width of 100-120 cm are sought, such as the mentioned Wall-mounted distributor box N-MAX 5 - 1200mm.
Schematic - how to measure the required box dimensions
Location of the cabinet in the house or apartment
The choice of location for the distributor cabinet is a compromise between technical requirements (length of circuits, accessibility for service, connection to the heat source) and the aesthetic requirements of the investor. In practice, we follow several rules.
Central placement in relation to the circuits
Ideally, the distributor (and thus its cabinet) should be placed as close as possible to the center of the floor plan of the heated rooms, so that the lengths of the individual floor circuits are as balanced as possible. Experience shows that the difference in length between the longest and shortest circuit from one distributor should not exceed approximately 15-20 meters - with a greater difference, the hydraulic adjustability of the system deteriorates and some circuits remain "lazy" even after the flow meters are adjusted. If the house floor plan is large or has an L or U shape, it is often more advantageous to choose two smaller distributors in two cabinets at suitable locations rather than one large distributor in a corner of the house.
Technical room vs. living space
If the layout allows, the most practical option is to place the cabinet in a technical room, boiler room, utility room or shaft - there the aesthetics do not matter, there is usually also a drainage point for possible air venting, and other utilities (electricity for actuators, possibly piping from the boiler) are usually nearby. In larger houses with distributors on each floor, however, this option is sometimes unavoidable and the cabinet has to go into the hallway, into a wardrobe or into a partition between rooms - in such a case, we clearly recommend an in-wall solution with designer doors, which can be painted or clad in the same color as the surrounding wall.
Mounting height
In underfloor heating, the distributor is mostly mounted low - the bottom edge of the cabinet about 10-20 cm above the level of the rough floor, because the piping is brought to the distributor from below from the distribution laid in the floor construction. When combined with radiator circuits or in solutions where the distributor is fed from a wall-mounted manifold, a higher placement (up to a height of 130-150 cm) is sometimes chosen, to make access to the regulation more comfortable without the need to bend down. However, this is already a matter of the designer's and investor's preference.
Schematic - typical cabinet placement in the house floor plan
Cabinet and floor construction - connection to footstep insulation
The distributor cabinet is not an insulated element - it must always be assessed in the context of the entire floor construction, through which the pipes of individual circuits enter and exit. The place where the pipe exits the floor towards the distributor is called a riser (or "entry to the distributor") and it must be protected by a protective sleeve (protector), to prevent the pipe from being damaged during concrete expansion or during possible replacement and to separate it from direct contact with the concrete.
A properly implemented floor construction also includes footstep (impact) insulation, which is laid under the entire area of the floor heating, including the area under the cabinet and its surroundings. It is used to prevent the transfer of noise and vibrations from the floor to the building structure and at the same time partially insulates thermally, so that heat is directed upwards into the space and not downwards into the neighbor's ceiling or into the ground. In our range you will find for example Footstep insulation - 1.5m; 6mm - pack 75m for larger areas or Footstep insulation - 1.0m; 6mm - pack 12.5m for smaller spaces and covering details around the cabinet. A detailed procedure for laying footstep insulation can be found in a separate article Footstep insulation - what it is for and how to lay it correctly.
When planning the location of the cabinet, it is important to know that the height of the floor construction (footstep insulation + system board + piping + concrete screed + finish layer) usually ranges between 10-15 cm. This value must be taken into account when setting the height of the cabinet - if the cabinet is installed too low without a reserve for the rough floor, after pouring the screed, it may happen that the bottom edge of the cabinet is below the level of the finished floor or, on the contrary, unnecessarily high above it with an unsightly gap.
Schematic - cross-section of the floor construction at the distributor cabinet
Space around the cabinet and accessibility for service
When choosing the location and size of the cabinet, you should also think about future service. Distributors are regularly vented, flow meters are checked, the hydraulic adjustment is changed when the use of the rooms changes (for example, after converting a basement into a living room), and actuators or thermostatic heads are occasionally replaced. Therefore:
- There should be at least 50-60 cm of free space in front of the cabinet, so that the doors can be fully opened and the technician can work comfortably with a key and measuring instruments.
- The cabinet should not be covered by furniture, a built-in wardrobe for clothes or any other permanent structure - in practice, we come across cases where the distributor cabinet is "built into" behind a kitchen unit and the service technician cannot reach it without partial dismantling of the kitchen.
- The electrical connection for actuators and any control unit should be brought out directly in the cabinet area or very close to it, ideally with its own box out of reach of moisture.
- If there is also a circulation pump in the cabinet (in a mixing unit for floor heating connected to a high-temperature boiler circuit), you need to plan access to the electrical socket or supply.
Common mistakes when selecting and installing a manifold cabinet in practice
Over the years of implementation and service, the same mistakes repeat themselves almost 90% of the time due to insufficient coordination between the builder, the heating technician, and the investor:
Too little depth reserve
The investor chooses a cabinet based on the catalog size of the manifold without actuators, but after installing thermostatic heads or electric actuators, the cabinet doors cannot close. The solution is always to calculate the depth with a reserve or to choose low-profile heads.
Recess built before the exact manifold is known
The builder builds a recess "approximately 60x80 cm", as this is the information received months ago during the design phase, but the heating technician later installs a different, larger manifold with 10 loops instead of the originally planned 6. The result is additional cutting of masonry, which is unnecessary work and additional cost. Recommendation: confirm the cabinet dimensions in writing (by email, in the project) with the heating technician before constructing the recess.
Cabinet placed too close to the edge of the floor plan
If the investor insists on placing the cabinet in the corner of the house far from the center of the heated loops for aesthetic reasons, the result is extremely different loop lengths and associated balancing problems - some rooms overheat, others do not heat up even with the flow meter fully open. In such cases, we recommend considering two smaller manifolds in two cabinets closer to the respective zones.
Underestimated height above the floor
A cabinet installed exactly at the level of the rough floor ends up partially below the level of the finished floor after pouring the screed and laying the tiles, which complicates pipe connections and looks unattractive. It is always necessary to subtract the planned height of the entire assembly (floor insulation, subfloor, screed, tiling) from the cabinet installation height.
Material and cabinet finish
Manifold cabinets are mostly made of galvanized or painted steel sheet (white color, most commonly RAL 9010 or a similar shade), which ensures sufficient structural rigidity and an aesthetic appearance. Doors are usually equipped with a lock or at least a safety catch against unintentional opening, which is practical especially in houses with children or in rented spaces where you do not want unqualified people to interfere with the regulation settings. Some cabinets have perforation or openings in the lower or upper part for air exchange and easier pipe and electrical cable routing - when choosing a specific model, pay attention to which side (top, bottom, side) these openings are prepared, so they match the actual pipe routing direction in your building.
Connection to other implementation steps
Selecting and installing a cabinet is only one step in the entire process. It follows the selection of the manifold itself and the number of loops (see How to choose a manifold for floor heating and How many loops and outlets do I need on the manifold?), continues with the actual installation (Installation of the manifold and manifold cabinet step by step), after the floor is completed, comes air venting and balancing (Air venting and balancing of the floor heating manifold) and in the future also regular maintenance (Maintenance and servicing of the heating system manifold). If the manifold shows unusual symptoms, such as dripping, noise or uneven heating, we also recommend checking the article Common manifold faults and their solutions - there you will find diagnostics of the most common problems.
Comparison of typical cabinet size categories
| Category | Typical number of loops | Estimated cabinet width | Application |
|---|---|---|---|
| Small cabinet | 3-6 loops | approx. 450-550 mm | apartment, small family house, one zone |
| Medium cabinet | 6-9 loops | approx. 535-700 mm | standard family house, one floor |
| Large cabinet | 10-16 loops / 2 manifolds | approx. 900-1200 mm | larger house, multiple zones, apartment building - common node |
Distance of the cabinet from the floor and from the corner of the space
In addition to the cabinet dimensions themselves, precise clearances are also addressed in practice, which determine exactly where the recess or anchoring points on the wall will be placed. In floor heating, the lower edge of the cabinet is referenced from the level of the rough floor (not from the finished walking surface), because at the time of the rough construction, the finished floor does not yet exist and the mason needs an exact reference from which to measure. Equally important is the lateral clearance of the cabinet from the corner of the room or from the adjacent wall - if the cabinet is installed too close to the corner, the doors may touch the adjacent wall or the door frame when opened, which is often a surprise during the final inspection. The recommended minimum lateral clearance from a fixed obstacle (corner, door frame, built-in cabinet) is at least 15-20 cm, so that the doors can be opened fully without restriction.
Diagram - cabinet clearances from the floor and from surrounding structures
Frequently asked questions about manifold cabinets
Must the manifold cabinet be larger than the manifold itself, or is the exact size sufficient?
The cabinet should always be larger than the pure dimensions of the manifold, at least 10-12 cm in width and a few centimeters in depth (due to actuators and key manipulation). An exact size "to measure" without reserve has not proven successful in practice - the doors are difficult to close and service is uncomfortable.
Can I install the manifold cabinet directly in the bathroom?
It is possible, but you must respect the zones of protection against moisture (similar to electrical installation) and choose a location away from direct contact with water, ideally outside the shower and bathtub. In practice, a cabinet in the bathroom is chosen only exceptionally if no other suitable layout exists.
How do I know if I need a wall-mounted or built-in cabinet?
If the cabinet is in a technical room, garage or boiler room, where appearance does not matter, a wall-mounted version is sufficient - it is cheaper and quicker to install. If it is to be in a living space, on a hallway or in a bedroom, we clearly recommend a built-in version, which after installation becomes almost invisible part of the wall.
What if I find out after installing the manifold that the cabinet is too small?
In case of a slight mismatch, sometimes help can be achieved by removing the side panels or modifying the internal layout, but in most cases it is necessary to replace the entire cabinet with a larger model. Therefore, it is important to select the cabinet simultaneously with the manifold, not sequentially and independently of each other.
Is it necessary to use floor insulation also under the cabinet?
Yes, step isolation should be continuous across the entire floor construction area, including the space under and next to the cabinet, otherwise an acoustic "bridge" is created through which noise and vibrations are transmitted from the floor to the structure. Cuts in the insulation should be made only precisely at the location of the pipe passage, not on a larger area.
Can the distributor cabinet be moved after the floor has been completed?
Theoretically yes, but in practice it is a complex and costly intervention, as it would be necessary to break the finished screed and extend or relocate the circuit pipes. Therefore, it is strongly recommended to carefully plan the location and dimensions of the cabinet already in the design phase, not as an afterthought.
Conclusion
Selecting a distributor cabinet is not just a matter of aesthetics or available space in the wall niche - it is a technical decision that affects the functionality of the entire floor heating system, the comfort of future service, and ultimately whether you manage to avoid additional construction modifications. The recommended procedure is simple: first choose a distributor according to the required number of circuits and type of regulation, then dimension the cabinet with an appropriate reserve in width, height and depth, place it as close as possible to the center of the heated circuits and ensure sufficient working space for future service. When choosing a specific model, you can be inspired by proven solutions such as Wall-mounted distributor cabinet N-MAX 1 - 450mm for smaller systems, Wall-mounted distributor cabinet N-KLASIK 2 - 535mm as a universal solution, or Wall-mounted distributor cabinet N-MAX 5 - 1200mm for larger systems with multiple zones. The full range of distributors and accessories can be found in the category Distributors and accessories, where you can combine a distributor, cabinet and step insulation in one step.
Do you have a question on this topic?
Not sure or dealing with a specific situation in your home? Write to us - we are happy to help.