The maximum number of underfloor heating circuits. Methodical recommendations for calculations for arranging a warm floor
The laying of heating pipes under the floor is considered one of the best options heating a house or apartment. They consume less resources to maintain the specified temperature in the room, exceed standard wall-mounted radiators in terms of reliability, evenly distribute heat in the room, and do not create separate "cold" and "hot" zones.
The length of the contour of a water-heated floor is the most important parameter that must be determined before starting installation works... The future power of the system, the level of heating, the choice of components and structural units depend on it.
Styling options
There are four common pipe layouts used by builders, each of which is better suited for indoor use. of various shapes... To a large extent depends on their "drawing" maximum length underfloor heating contour. It:
- "Snake". Sequential styling, where the hot and cold lines follow each other. Suitable for elongated rooms with division into zones of different temperatures.
- "Double snake". Applied in rectangular rooms but no zoning. Provides uniform heating of the area.
- "Corner snake". Sequential system for a room with equal wall lengths and a low heating zone.
- "Snail". Double laying system, suitable for close to square room shapes without cold spots.
The chosen installation option affects the maximum length of the water floor, because the number of pipe loops and the bending radius change, which also "eats" a certain percentage of the material.
Length calculation
The maximum pipe length for underfloor heating for each circuit is calculated separately. To get the required value, you need the following formula:
W * (L / Shu) + Shu * 2 * (L / 3) + K * 2
The values are indicated in meters and mean the following:
- W is the width of the room.
- D is the length of the room.
- Shu - "laying step" (the distance between the loops).
- K is the distance from the collector to the point of connection with the contours.
The length of the underfloor heating contour obtained as a result of calculations is additionally increased by 5%, which includes a small margin for leveling errors, changing the bending radius of the pipe and connecting to fittings. 
As an example of calculating the maximum pipe length for a warm floor for 1 circuit, we take a room of 18 m2 with sides of 6 and 3 m.The distance to the collector is 4 m, and the laying step is 20 cm, the following is obtained:
3*(6/0,2)+0,2*2*(6/3)+4*2=98,8
5% is added to the result, which is 4.94 m and the recommended length of the water floor heating circuit is increased to 103.74 m, which is rounded up to 104 m.
Dependence on pipe diameter
The second most important characteristic is the diameter of the pipe used. It directly affects maximum value lengths, the number of circuits in the room and the power of the pump, which is responsible for the circulation of the coolant.
In apartments and houses with an average room size, pipes of 16, 18 or 20 mm are used. The first value is optimal for residential premises, it is balanced in terms of cost and performance. The maximum length of the water underfloor heating circuit with 16 pipes is 90-100 m, depending on the choice of pipe material. It is not recommended to exceed this indicator, because the so-called "closed loop" effect can occur, when, regardless of the pump power, the movement of the coolant in the communication stops due to the high resistance of the liquid.
To choose optimal solution and take into account all the nuances, it is better to contact our specialist for advice. 
Number of circuits and power
The installation of the heating system must comply with the following recommendations:
- One loop per room of a small area or part of a large one; it is irrational to stretch the contour over several rooms.
- One pump per manifold, even if the declared capacity is sufficient to provide two “combs”.
- With a maximum floor heating pipe length of 16 mm in 100 m, the collector is installed on no more than 9 loops.
If the maximum length of the underfloor heating loop 16 pipes exceeds the recommended value, then the room is divided into separate circuits, which are connected into one heating network by a collector. To ensure an even distribution of the coolant throughout the entire system, experts advise not to exceed the difference between individual loops of 15 m, otherwise the smaller circuit will warm up much more than the larger one.
But what if the length of the underfloor heating circuit of a 16 mm pipe differs by a value that exceeds 15 m? Balancing fittings will help, which changes the amount of coolant circulating through each loop. With its help, the difference in lengths can be almost two times. 
Room temperature
Also, the length of the underfloor heating circuits for 16 pipes affects the heating level. To maintain a comfortable indoor environment, a certain temperature is required. For this, the water pumped through the system is heated to 55-60 ° C. Exceeding this indicator can adversely affect the integrity of the material. engineering communications... Depending on the purpose of the room, on average, we get:
- 27-29 ° C for living rooms;
- 34-35 ° C in corridors, hallways and walkways;
- 32-33 ° C in rooms with high humidity.
In accordance with the maximum length of the underfloor heating circuit of 16 mm in 90-100 m, the difference at the "inlet" and "outlet" of the mixing boiler should not exceed 5 ° C, a different value indicates heat loss on the heating main.
"Warm floors" have long been no longer perceived as a kind of exotic - more and more homeowners are turning to this technology for heating their residential properties. Such a system can completely take over the function of full-fledged heating of the home, or work in tandem with classic heating devices- or convectors. Naturally, these features are taken into account in advance, at the stage of general design.
There are more than enough proposals for project development, installation and debugging of systems. And yet, many home owners, according to the good old tradition, strive to do everything with their own hands. But such work "by eye" is still not done - one way or another, calculations are required. And one of the key parameters is the general permissible length pipes of one circuit.
And since in the conditions of an ordinary average private residential building, as a rule, a pipe with a diameter of 16 mm is quite enough for laying, then we will stop at it. So, we are considering the question of what can be the maximum length of the underfloor heating circuit with a 16 pipe.
Why is it better to use a pipe with an outer diameter of 16 mm?
To begin with - why is the 16 mm pipe being considered?
Everything is very simple - practice shows that this diameter is quite enough for "warm floors" in a house or apartment. That is, it is difficult to imagine a situation when the contour will not cope with its task. This means that there is no really justified reason to use a larger, 20 mm one.
And, at the same time, the use of a 16 mm pipe provides a number of advantages:
- First of all, it is about a quarter cheaper than its 20mm counterpart. The same applies to all the necessary fittings - the same fittings.
- Such pipes are easier to lay, with them it is possible, if necessary, to perform a compacted step of the contour layout, up to 100 mm. With a 20 mm pipe, there is much more fuss, and a small step is simply impossible.
- The volume of the coolant in the circuit is significantly reduced. A simple calculation shows that in running meter 16 mm pipe (with a wall thickness of 2 mm, the inner channel is 12 mm) holds 113 ml of water. And in 20 mm (inner diameter 16 mm) - 201 ml. That is, the difference is more than 80 ml for just one meter of pipe. And on the scale of the heating system of the whole house - this literally translates into a very decent amount! And after all, it is necessary to ensure the heating of this volume, which entails, in principle, unjustified costs for energy carriers.
- Finally, a pipe with a large diameter will require an increase in thickness. concrete screed... Whether you want it or not, you will have to provide a minimum of 30 mm above the surface of any pipe. Let not these "unfortunate" 4–5 mm seem ridiculous. Anyone who was engaged in pouring the screed knows that these millimeters turn into tens and hundreds of kilograms of additional concrete mortar- it all depends on the area. Moreover, for a 20 mm pipe, it is recommended to make the screed layer even thicker - about 70 mm above the contour, that is, it turns out to be almost twice as thick.
In addition, in living quarters there is often a "struggle" for every millimeter of floor height - simply for reasons of insufficient "space" to increase the thickness of the overall "pie" of the heating system.
The 20-mm pipe is justified when it is necessary to perform a floor heating system in rooms with high loads, with a large traffic intensity, in gyms, etc. There, simply for reasons of increasing the strength of the base, it is necessary to use more massive thick screeds, which require and big square heat transfer, which is exactly what the pipe 20, and sometimes even 25 mm provides. In living quarters, there is no need to resort to such extremes.
It may be objected that in order to "push" the coolant through a thinner pipe, it will be necessary to increase the power indicators of the circulation pump. Theoretically, this is the way it is - the hydraulic resistance, of course, increases with decreasing diameter. But as practice shows, most circulation pumps quite cope with this task. Below we will pay attention to this parameter - it is also linked to the length of the contour. That is why calculations are carried out in order to achieve optimal or, at least, acceptable, quite workable indicators of the system.
So, let's focus on the pipe exactly 16 mm. We will not talk about the pipes themselves in this publication - that is, there is a separate article on our portal.
What pipes are optimal for a water "warm floor"?
Not all products are suitable for creating a floor heating system. Pipes are embedded in the screed for many years, that is, to their quality and operational characteristics special requirements apply. How to choose - read in a special publication of our portal.
How to determine the length of the contour?
The question seems completely straightforward. The fact is that on the Internet you can find a lot of recommendations on this matter - both from pipe manufacturers and from experienced craftsmen, and from, let's be honest, absolute amateurs who simply "distort" information from other resources, without going into the details.
So, in the installation instructions, with which manufacturers often accompany their products, you can find the established limit for the length of the circuit for a 16 mm pipe reaching 100 meters. Other publications show a border of 80 meters. Experienced installers recommend limiting the length to 60 ÷ 70 meters.
It would seem, what else is needed?
But the fact is that the indicator of the length of the contour, especially with a vague definition of "maximum length", is very difficult to consider in isolation from other parameters of the system. To lay out the contour "by eye", just so as not to exceed the recommended boundaries - an amateurish approach. And with such an attitude, it is quite possible to soon face deep disappointments in the operation of the system. Therefore, it is better to operate not with the abstract "permissible" length of the contour, but with the optimal one, corresponding to specific conditions.
And it depends (more precisely, does not depend so much on how much it is closely interconnected) on the mass of other parameters of the system. This can include the area of the room, its purpose, the calculated level of its heat loss, the expected temperature in the room - all this will make it possible to determine the step of laying the contour. And only then it will be possible to judge its resulting length.
So we will try to "unravel this tangle" to come to optimal length contour. And then we will check the correctness of our calculations.
Several basic requirements for the parameters of "warm floor"
Before proceeding with the calculations, you need to familiarize yourself with some of the requirements that a water floor heating system must meet.
- "Warm floor" can act as the main heating system, that is, fully provide a comfortable microclimate in the premises of the house and compensation for heat losses. Another option, more rational - he acts as a "helper" conventional radiators or convectors, taking on a certain share in common work systems, increasing the overall comfort in the home. In this case, the calculation should be carried out in close relationship - the owners must determine in advance in what ratio the overall system will work. For example, 60% is taken over by the high-temperature system of radiators, and the rest is given to the contours of the "warm floor". It can also be used autonomously, for example, maintaining comfort in rooms in the off-season, when it still (or already) does not make sense to "drive the entire heating system to full".
- The temperature of the coolant at the supply to the "warm floor" is limited to a maximum of 55 degrees. The temperature difference at the inlet and in the return must be in the range from 5 to 15 degrees. A fall of 10 degrees is considered normal (it is desirable to bring it to 5 - 7).
The following modes of operation are usually taken into account.
Table of operating modes of the water "warm floor"
- There are rather strict restrictions on the maximum temperature of the "warm floor" surface. Overheating of floors is not allowed for a variety of reasons. This is both an uncomfortable sensation for a person's feet, and difficulties in creating an optimal microclimate, and possible deterioration of the finish coat.
The following limit values for surface heating have been established for various rooms:
- Before starting the calculations, it is advisable to immediately draw up an example scheme layout of the contour in the room. There are two main pipe-laying schemes - "snake" and "snail" with multiple variations.
A - the usual "snake";
B - double "snake";
B - angular "snake";
G - "snail".
The usual "snake" seems to be laid out easier, but it turns out too many turns by 180 degrees, which increases the hydraulic resistance of the circuit. In addition, with such a layout, the temperature difference from the beginning of the circuit to the end can clearly be felt - this is well shown in the diagram by changing the color. The disadvantage can be eliminated by laying a double snake, but such an installation is already more difficult to perform.
In the "snail" heat is distributed more evenly. In addition, 90 degree bends are predominant, which reduces head losses. But it is still more difficult to fit such a scheme, especially if there is no experience in such work.
The circuit itself may not occupy the entire area of the room - often the pipes are not laid in those places where the installation of stationary furniture is planned.
However, many masters criticize this approach. The stationarity of furniture is still a rather arbitrary value, and the "warm floor" is laid for decades. In addition, the alternation of cold and hot zones is an undesirable phenomenon, at least from the point of view of the possible appearance of dampness centers over time. Unlike electrical systems, local overheating due to closed areas does not threaten water floors, so there should be no fears from this side.
So there is no strict framework on this score. You can, in order to save material, leave empty areas, or lay the contour completely over the entire area. But if in some area it is planned to install pieces of furniture or plumbing devices requiring fastening to the floor (for example, fixing the toilet with dowels or anchors), then this place, of course, remains free from the contour. It is simply very likely that the pipe will be damaged when installing the fasteners.
What is the best way to lay the contour?
More details about the choice of laying schemes, with theoretical justifications, are described in a separate article on our portal.
- The pipe laying step can be from 100 to 300 mm (usually it is a multiple of 50 mm, but this is not a dogma). It is neither possible nor necessary to perform less than 100 mm. And with a step of more than 300 mm, you can feel the "zebra effect", that is, the alternation of warm and cold stripes.
But what step will be optimal - the calculations will show, since it is closely related to the expected heat transfer of the floor and the temperature regime of the system.
- Another caveat - all subsequent heat engineering calculations shown for the optimum pie sizes of the underfloor heating system.
It was said above that the thickness of the screed should be at least 300 mm above the surface of the pipes. But to ensure full accumulation and uniform distribution heat, it is recommended to adhere to a thickness of 45-50 mm (specifically for a pipe with a diameter of 16 mm).
Find out how to do it right, choose a mixture, prepare a solution, and also familiarize yourself with the technology of pouring a water and electric underfloor heating.
And so that the generated heat is not wasted on heating interfloor overlap or other base of "warm floor", a thermal insulation layer is necessarily provided under the pipe circuit. Usually, for this, expanded polystyrene with a density of about 35 kg / m³ is used (better - extruded, as it is more durable and efficient). Minimum thickness ensuring the correct operation of the "warm floor" should be:
| Features of the base of the "warm floor" | The minimum thickness of the thermal insulation "cushion" |
|---|---|
| Floor over the ceiling above the heated room, the temperature in which is ˃ 18 ° С | 30 mm |
| 50 mm | |
| Floor over the ceiling above the heated room, the temperature in which is from 10 to 17 ° С | 70 mm |
| Floor on the ground, including in basements or basements with a depth from ground level up to 1500 mm. | 120 mm |
| Floor in basements or basements with a depth of more than 1500 mm from the ground level | 100 mm |
A prerequisite is that the underfloor heating system must be laid on a carefully insulated base, otherwise the heat will be consumed extremely inefficiently All of these last remarks were made because the following calculations will be valid precisely for such recommended "ideal" conditions.
Calculations of the main parameters of the contour
In order to lay the pipe loop with the optimal pitch (and its overall length will subsequently depend on this), it is first necessary to find out what heat transfer is expected from the system. This is best shown by the specific heat flux density g, calculated per unit of floor area (W / m²). Let's start with this.
Calculation of the specific heat flow density of the "warm floor"
Calculating this value, in principle, is not difficult - you just need to divide the required amount of thermal energy required to replenish the heat loss of the room by the area of the "warm floor". This does not mean the entire area of the room, namely "active", that is, involved in the heating system, on which the circuit will be laid out.
Of course, if the "warm floor" will work in conjunction with conventional system heating, this is also immediately taken into account - only the planned percentage of the total heat capacity is taken. For example, for heating a room (replenishing heat loss), 1.5 kW is required, and the share of the "warm floor" is assumed to be 60%. This means that when calculating the specific density of the heat flux, we operate with a value of 1.5 kW × 0.6 = 0.9 kW
Where to get the indicator of the total required power to replenish heat losses? There are many recommendations to proceed from the ratio of 1 kW of energy per 10 m² of floor space. However, this approach turns out to be too approximate, not taking into account the mass of important external factors and the features of the room. Therefore, it is better to make a more careful calculation. Don't be alarmed - with our calculator it won't be too difficult.
Calculator for calculating the specific heat flux of "warm floor"
Warm floor perfect solution for the improvement of your home. The floor temperature directly depends on the length of the underfloor heating pipes hidden in the screed. The pipe in the floor is laid in loops. In fact, from the number of loops and their length, the total length of the pipe is added. It is clear that the longer the pipe in the same volume, the warmer the floor. In this article, we will talk about the restrictions on the length of one contour of the warm floor.
Approximate design characteristics for pipes with a diameter of 16 and 20 mm are: 80-100 and 100-120 meters, respectively. These data are approximate for approximate calculations. Let's take a closer look at the process of installing and pouring underfloor heating.
The consequences of exceeding the length
Let's figure out what consequences an increase in the length of the underfloor heating pipe can lead to. One of the reasons is an increase in hydraulic resistance, which will create an additional load on the hydraulic pump, as a result of which it may fail or it may simply not be able to cope with the task assigned to it. Resistance calculation consists of many parameters. Conditions, styling parameters. The material of the pipes used. There are three main ones: loop length, number of bends and heat load on it.
It is worth noting that the heat load increases with increasing loop. The flow rate and hydraulic resistance also increase. There are restrictions on the flow rate. It should not exceed 0.5 m / s. If we exceed this value, various noise effects may occur in the piping system. The main parameter, for the sake of which this calculation is done, also increases. The hydraulic resistance of our system. There are restrictions on it too. They are 30-40 kP per loop.
The next reason is that with an increase in the length of the underfloor heating pipe, the pressure on the pipe walls increases, causing this section to elongate when heated. The pipe in the screed has nowhere to go. And it will begin to taper at the weakest point. The restriction can cause blockage of the flow in the heating medium. For pipes made of different material, different expansion coefficient. For example, in polymer pipes the expansion coefficient is very high. All these parameters must be taken into account when installing a warm floor.
Therefore, it is necessary to fill the underfloor heating screed with pressed pipes. It is better to pressurize with air at a pressure of about 4 bar. Thus, when you fill the system with water and start heating it, the pipe in the screed will be where it will expand.
Optimum pipe length
Considering all the above reasons, taking into account the corrections for the linear expansion of the pipe material, we take as a basis the maximum length of the underfloor heating pipes per circuit:
The table shows optimal sizes underfloor heating lengths that are suitable for all modes of thermal expansion of pipes in various operating modes.
Note: B residential buildings a 16 mm pipe is enough. A larger diameter should not be used. This will lead to unnecessary waste on energy.
1. What temperature should be the coolant in the warm floor and how can its temperature be controlled?
The temperature should be no higher than 55 ° C, and in some cases no higher than 45 ° C.
To put it more precisely: the temperature should be in accordance with the temperature calculated in the project, which takes into account the need for a particular room for heat and the material from which the floor is made.
You can control the temperature with such a thermometer, or better than two.
One thermometer shows the temperature of the heating medium at the underfloor heating supply (temperature mixed water), and the other is the return temperature.
If the difference between the readings of the two thermometers is 5 - 10 o C, then your underfloor heating system is working correctly.
2. What should be the temperature on the underfloor heating surface?
The surface temperature of a working underfloor heating must not exceed the following values:
29 o C - in premises for long-term presence of people;
35 o C - in the border zones;
33 o C - in toilets, bathrooms.
3. What forms of pipe laying are used for underfloor heating?
For pipe laying underfloor heating use different shapes: snake, corner snake, snail, double snake (meander).
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Also, when laying one contour, you can combine these shapes.
For example, the edge zone can be positioned with a snake, and then the main part can be traversed with a snail.
4. What is the best installation for underfloor heating?
For large rooms of a square, rectangular or round shape without geometric exclusivity, it is better to use a snail.
For small rooms, rooms with complex forms or long rooms, use a snake.
5. What should be the laying step?
The laying step should be designed in accordance with the calculations.
For the marginal zones, a step of 10 cm is used.For other zones with a difference of 5 cm - 15 cm, 20 cm, 25 cm.But no more than 30 cm.
This limitation is due to the sensitivity of the person's foot.
With a larger pipe pitch, the leg begins to feel the temperature difference between the floor areas.
To do this, you can use a very simple formula: L = S / N * 1.1, where
S is the area of the room or circuit for which the pipe length is calculated (m 2);
N - laying step;
1.1 - pipe stock of 10% for turns.
Do not forget to add the length of the pipe from the collector to the underfloor heating to the result obtained, including supply and return.
For example, consider a problem in which you need to calculate the length of a pipe for a room in which the floor occupies a useful area of 12 m 2. The distance from the collector to the warm floor is 7 m. The pipe laying step is 15 cm (do not forget to translate into m).
Solution: 12 / 0.15 * 1.1 + (7 * 2) = 102 m.
7. What is the maximum length of one circuit?
It all depends on the hydraulic resistance or pressure losses in a particular circuit, which, in turn, directly depend both on the diameter of the pipes used and on the volume of the coolant that is supplied through the cross section of these pipes per unit of time.
In the case of underfloor heating, (if the above factors are not taken into account), you can get the effect of the so-called locked loop. A situation in which no matter how powerful in terms of head you put the pump, circulation through this loop will be impossible.
In practice, it has been found that a pressure loss of 20 kPa or 0.2 bar just leads to this effect.
In order not to go into the calculations, here are some recommendations that we use in practice.
For metal-plastic pipe with a diameter of 16 mm, we make a contour of no more than 100 m.Usually, we stick to 80 m.
The same goes for polyethylene pipes. For 18 XLPE pipes, the maximum loop length is 120 m.In practice, we stick to 80 - 100 m. For 20 multilayer pipes, the maximum loop length is 120 - 125 m.
8. Can there be underfloor heating contours of different lengths?
The ideal situation is when all the loops are the same length. There is no need to balance or adjust anything.
In practice, this can be achieved, but more often than not it is not advisable.
For example, there is a group of rooms at the facility where you need to make a warm floor. Among them there is also a bathroom, the usable floor area of which is 4 m 2. Accordingly, the length of the pipeline of this circuit, together with the length of the pipes to the collector, is only 40 m.
Is it really necessary to adjust all rooms to this length, dividing the usable area of the remaining rooms by 4 m 2?
Of course not. It is not advisable. And then what is the balancing armature, which is designed to help equalize the pressure loss across the circuits?
Again, you can use the calculations, through which you can see to what maximum limit you can allow the spread of the lengths of pipes of individual circuits at a particular facility with this equipment.
But again, without immersing you in complex boring calculations, we will say that at our facilities we allow a variation in the lengths of pipes of individual circuits by 30 - 40%. Also, if necessary, you can "play" with the diameters of the pipes, the laying step and "cut" the area of large rooms not into small or large, but into medium pieces.
9. How many circuits can be connected to one mixing unit with one pump?
Physically, this question is similar to the question: "How much cargo can you carry by car?"
What else would you like to know if someone asked you this question?
Absolutely right. You would ask: "What kind of car are we talking about?"
Therefore, in the question: "How many loops can be connected to the underfloor heating collector?", You need to take into account the diameter of the collector and what volume of the coolant the mixing unit is able to pass through itself per unit of time (it is usually considered m 3 / hour). Or, which is also equivalent, what kind of heat load is capable of carrying the mixing unit of your choice?
How to find out? Very simple.
For clarity, we will show with an example.
Suppose you have a Valtec Combimix as your mixing unit. What heat load is it designed for? We take his passport. See passport clipping.
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What do we see?
Its maximum coefficient bandwidth is 2.38 m 3 / hour. If we install a Grundfos UPS 25 60 pump, then at the third speed at this ratio this unit is able to "drag off" a load of 17000 W or 17 kW.
What does this mean in practice? How many circuits is 17 kW?
Imagine that we have a house in which there are some (unknown) rooms of 12 m 2 of usable floor heating area in each room. Our pipes are laid with a step of 20 cm, which leads to the length of each circuit, taking into account the length of the pipes from the warmest floor to the collector, 86 m.In accordance with the design calculations, we also obtained that the heat removal from each m2 of this warm floor gives 80 W , which leads us, respectively, to the heat load of each circuit
12 * 80 = 960 watts
How many rooms or similar circuits can our mixing unit provide with heat?
17,000 / 960 = 17.7 similar circuits or rooms.
But this is the maximum!
In practice, in most cases, it is not necessary to calculate the maximum performance. Therefore, we will focus on the number 15.
Valtec itself has a manifold with a maximum number of outputs - 12 to this node.
10. Do I need to make several contours of the warm floor in large rooms?
In large rooms, the underfloor heating structure should be divided into smaller areas and several contours should be made.
This need arises for at least two reasons:
limiting the length of the circuit pipe is necessary in order not to obtain the effect of a "locked loop", in which there will be no circulation of the coolant through it;
correct operation of the cement filler plate itself, the area of which should not exceed 30 m 2. WITHThe ratio of the lengths of its sides should be 1/2 and the length of one of the edges should not exceed 8 m.
11. How do I know how many underfloor heating circuits are needed for my home?
In order to understand how many loops of underfloor heating will be needed and, on the basis of this, choose a suitable collector with the same number of outputs, you need to start from the area of the premises themselves in which this system is planned.
After that, you calculate the usable floor area. How to do this is described in question 12 " How to calculate the usable floor area?".
Then, use the following method: starting from the step of the warm floor, break the usable area of the warm floor in each room into the following dimensions:
- step 15 cm - no more than 12 m 2;
- step 20 cm - no more than 16 m 2;
- step 25 cm - no more than 20 m 2;
- step 30 cm - no more than 24 m 2.
If the floor area in the room is less than the specified dimensions, then it does not need to be broken.
We recommend reducing these values by 2 m 2 if the length of the pipe connection from the underfloor heating to the collector exceeds 15 m.
When dividing the usable floor area in the premises, try also to achieve that the length of the pipes in these circuits is either the same, or the difference between the individual circuits does not exceed 30 - 40%.How to find out the length of the pipes in each circuit, read in question 6 " How to calculate pipe length?".
Step back 30 cm from each of the walls of the room. Shade the resulting space. Mark on the plan the areas where the furniture will constantly stand: refrigerator, furniture wall, sofa, large wardrobe, etc. Shade these areas as well. The unshaded part of the floor plan will be the usable floor heating area that you are looking for.
For clarity, let's calculate the usable area of the dining room, where the heated floor will be. The total area of the dining room is 20 m 2, the length of the walls is 4 m and 5 m, respectively. kitchen set, refrigerator and sofa, which we mark on the plan. Let's not forget to step back from the walls by 30 cm. Shade the occupied areas. See drawing.
Now let's calculate the useful area of the warm floor.
13. What is the total thickness of the underfloor heating cake?
It all depends on the thickness of the insulation, since the rest of the values are known.
With the following insulation thickness, you will get the following values (the thickness of the finishing coating is not taken into account):
- 3 cm - 9.5 cm;
- 8 cm - 14.5 cm;
- 9 cm - 15.5 cm.
14. What do you use to calculate the water floor heating system?
To calculate both radiator heating systems and underfloor heating systems, we use the company's Audytor CO program.
Below we post a screenshot of the module of this program for the preliminary calculation of the warm floor and a screenshot of the module for the calculation of the layers of the warm floor pie.
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Upon closer examination of these screenshots, you can understand how serious the correct calculation of the warm floor is.
You can also see the work of the program itself, which does possible holding visual control over such important parameters such as pipe length, pressure loss, temperature at the floor surface, heat that goes down uselessly, useful heat flow, etc.
15. How to determine the dimensions of the manifold cabinet in order to accommodate all the necessary units in it?
It is not difficult to determine the dimensions of the manifold cabinet. We again suggest using Valtec products and their ready-made recommendations presented in the table, provided that you are using ready-made units for underfloor heating produced by this manufacturer.
Linear dimensions of the manifold cabinet
(ШРН - external; ШРВ - internal)
| Model | Length, mm | Depth mm | Height, mm |
|---|---|---|---|
| SHRV1 | 670 | 125 | 494 |
| SHRV2 | 670 | 125 | 594 |
| ShRV3 | 670 | 125 | 744 |
| SHRV4 | 670 | 125 | 894 |
| SHRV5 | 670 | 125 | 1044 |
| SHRV6 | 670 | 125 | 1150 |
| SHRV7 | 670 | 125 | 1344 |
| SHRN1 | 651 | 120 | 453 |
| SHRN2 | 651 | 120 | 553 |
| SHRN3 | 651 | 120 | 703 |
| SHRN4 | 651 | 120 | 853 |
| SHRN5 | 651 | 120 | 1003 |
| SHRN7 | 658 | 121 | 1309 |
Selection of a manifold cabinet
Collector groups 1 |
Cabinet model |
Cabinet model SHRN / SHRV + Dualmix + ball valve |
Cabinet model ShRN / ShRV + crane |
| Collector 1 * 3out | SHRN3 / SHRV3 | ShRN4 / ShRV4 | SHRN1 / SHRV1 |
| Collector 1 * 4out | SHRN3 / SHRV3 | ShRN4 / ShRV4 | SHRN2 / SHRV2 |
| Collector 1 * 5out | ShRN4 / ShRV3 | SHRN5 / SHRV4 | SHRN2 / SHRV2 |
| Collector 1 * 6out | ShRN4 / ShRV4 | SHRN5 / SHRV5 | SHRN3 / SHRV3 |
| Collector 1 * 7out | ShRN4 / ShRV4 | SHRN5 / SHRV5 | SHRN3 / SHRV3 |
| Collector 1 * 8out | SHRN5 / SHRV4 | SHRN6 / SHRV5 | SHRN3 / SHRV3 |
| Collector 1 * 9out | SHRN5 / SHRV5 | SHRN6 / SHRV6 | ShRN4 / ShRV4 |
| Collector 1 * 10out | SHRN5 / SHRV5 | SHRN6 / SHRV6 | ShRN4 / ShRV4 |
| Collector 1 * 11out | SHRN6 / SHRV5 | SHRN7 / SHRV6 | ShRN4 / ShRV4 |
| Collector 1 * 12out | SHRN6 / SHRV6 | SHRN7 / SHRV7 | SHRN5 / SHRV5 |
16. At what height should the manifold cabinet be installed?
There are no specific rules on this, but there are recommendations.
On the one hand, it is clear that when assembling the manifold cabinet, you need to take into account the height of the future screed and finish, so that a situation does not turn out when it will not even be possible to open the cabinet door.
On the other hand, the ease of maintenance and the need for possible replacement individual elements of the system with the likelihood of pipeline disconnection.
The shorter the pipe section, the greater its rigidity and vice versa.
Considering this factor, it is possible to raise the collector cabinet by 20 - 25 cm from the level of the clean floor.
However, one must not forget about a very important design element. If lifting the cabinet leads to an unacceptable violation of the design and it is impossible to solve this problem in another way, lower the cabinet to the floor level, but so that it can be opened.
Impossible without preliminary calculations. To get the length of the pipes, the power of the entire heating system and others desired values, you will only need to enter accurate data into the online calculator. You can learn more about the rules and nuances of the calculation below.
General data for calculation
The first parameter that must be taken into account before the calculations is the choice of the heating system option: whether it will be the main or auxiliary. In the first case, it must have more power in order to independently heat the whole house. The second option is applicable for rooms with low heat transfer from radiators.The temperature regime of the floor is selected according to building codes:
- The floor surface of the living space should be heated to 29 degrees.
- At the edges of the room, the floor can be heated up to 35 degrees to compensate for heat loss through cold walls and from drafts from opening doors.
- Bathrooms and areas with high humidity optimum temperature- 33 degrees.
If the arrangement of the warm floor is carried out under the bottom parquet boards, then you need to take into account that the temperature should not exceed 27 degrees, otherwise the flooring will quickly deteriorate.
The following are used as auxiliary parameters:
- total length pipes and their pitch (installation distance between pipes)... It is calculated thanks to the auxiliary parameter in the form of the configuration and the area of the room.
- Heat loss... This parameter takes into account the thermal conductivity of the material from which the house is built, as well as its degree of deterioration.
- Flooring... The choice of flooring affects the thermal conductivity of the floor. The use of tiles and porcelain stoneware is optimal, since they have high thermal conductivity and quickly warm up. When choosing linoleum or laminate, it is worth purchasing a material that does not have a thermal insulation layer. From wood covering it is worth abandoning, since such a floor will practically not heat up.
- Local climate, in which there is a building with a floor heating system. It is necessary to take into account the seasonal changes in temperatures in this region and the lowest temperature in winter.
Most of the heat escapes from the dwelling through its thin walls and substandard materials of the window structure. Before performing the heating system under consideration, it makes sense to insulate the house itself, and then calculate its heat loss. This will significantly reduce the energy consumption of its owner.
Calculation of pipes for underfloor heating
Water heat-insulated floor - connection of pipes that are connected to the collector. It can be made of metal-plastic, copper or corrugated pipes... In any case, it is necessary to correctly determine its length. For this, it is proposed to use a graphical method.The future contour is drawn on graph paper in scale or in full size " heating element», Having previously selected the type of pipe laying. As a rule, the choice is made in favor of one of two options:
- Snake... It is selected for small living spaces with low heat losses. The pipe is positioned like an elongated sinusoid and extends along the wall to the collector. The disadvantage of this installation is that the coolant in the pipe gradually cools down, so the temperature at the beginning and end of the room can be very different. For example, if the pipe length is 70 m, then the difference may be 10 degrees.
- Snail... Such a scheme assumes that the pipe is initially laid along the walls, and then bends 90 degrees and twists. Thanks to this installation, it is possible to alternate cold and hot pipes, getting an evenly warming surface.
Having chosen the type of stacking, the following indicators are taken into account when implementing the scheme on paper:
- The pipe pitch allowed in the spiral varies from 10 to 15 cm.
- The length of pipes in the circuit does not exceed 120 m.To determine the exact length (L), you can use the formula:
L = S / N * 1.1, where
S- area covered by the contour (m2);
N- step (m);
1,1 - the safety factor for bends.It should be understood that the pipe should be located in one piece from the outlet of the pressure manifold to the "return".
- The diameter of the pipes to be laid is 16 mm, and the thickness of the screed does not exceed 6 cm. There are also diameters of 20 and 25. Ideally, the larger this parameter, the higher the heat transfer of the system.
- Water consumption per hour with a pipe diameter of 16 cm can reach from 27 to 30 liters per hour.
- To warm up the room to a temperature of 25 to 37 degrees, the system itself needs to heat up to 40-55 ° C.
- Reducing the temperature in the circuit to 15 degrees will help a pressure loss in the body of 13-15 kPa.
Calculation of the power of a water-heated floor
It begins in the same way as in the previous method - with the preparation of graph paper, only in this case it is necessary to apply not only contours to it, but also the location of windows and doors. Draw scaling: 0.5 meter = 1 cm.To do this, it is worth considering several conditions:
- Pipes must be placed along the windows to prevent significant heat loss through them.
- The maximum area for arranging a warm floor should not exceed 20 m2. If the room is larger, then it is divided into 2 or more parts, and a separate contour is calculated for each of them.
- It is necessary to maintain the required value from the walls to the first branch of the contour of 25 cm.
Determining the number of pipes is quite simple: first measure their length, and then multiply it by a scale factor, add 2 m to the resulting length to supply the circuit to the riser. Considering that the permissible pipe length is in the range from 100 to 120 m, the total length must be divided by the selected length of one pipe.
The parameter of the underfloor heating is determined based on the area of the room, which is obtained after multiplying the length and width of the room. If the room has a complex configuration to obtain an accurate result, it must be divided into segments and the area of each of them must be calculated.
Examples of calculating a water heat-insulated floor
Next, you can familiarize yourself with two examples of calculating a water-heated floor:Example 1
In a room with a wall length of 4 × 6 m, furniture in which occupies almost a fourth of it, the warm floor should occupy at least 17 m2. For its implementation, pipes with a diameter of 20 mm are used, which are laid like a snake. A step of 30 cm is maintained between them. Laying is performed along a short wall.Before laying the pipes, you must draw a diagram of their location on the floor in the most appropriate scale. In total, such a room will fit 11 rows of pipes, each of which will be 5 m long, in total, 55 m of the pipeline will turn out. Another 2 m is added to the resulting pipe length. It is this distance that must be maintained before connecting to the riser. The total length of the pipes will be 57 m.
If the room is very cold, it may be necessary to lay double-circuit heating... Then you should stock up on at least 140 m of pipes, such a length of the pipeline will help to compensate for the strong pressure drop at the outlet and inlet of the system. You can make each contour of different lengths, but the difference between them should not be more than 15 meters. For example, one contour is performed with a length of 76 m, and the second - 64 m.
The calculation of a warm floor can be carried out in two ways:
- For the first method, the formula is applied:
L = S? 1.1 / B, where
L- the length of the pipeline;
B- laying step, measured in meters;
S- heating area, in m2. - In the second option, the tabular data below are used. They are multiplied by the area of the contour.
Example 2
It is required to conduct a warm floor in a room with a wall length of 5x6 m, the total area of which is 30 m2. For the system to work effectively, it must heat at least 70% of the space, which is 21 m2. Let's assume that the average heat loss is about 80 W / m2. So, the specific heat loss will be 1680 W / m2 (21x80). The desired temperature in the room is 20 degrees, while pipes with a diameter of 20 mm will be used. 7 cm screed and tiles are laid on them. The relationship between the step, the heat of the coolant, the heat flux density and the pipe diameter is shown in the diagram:
So, if there is a 20 mm pipe, to compensate for a heat loss of 80 W / m2, 31.5 degrees will be required at a step of 10 cm and 33.5 degrees at a step of 15 cm.
The temperature on the floor surface is 6 degrees lower than the temperature of the water in the pipes, which is due to the presence of a screed and coating.
Video: Calculation of a warm water floor
From the video it will be possible to learn the theory of hydraulics associated with the arrangement of warm floors, its application to calculations, an example of calculating a water heated floor in a special online program. First, simple pipe connection chains for such a floor will be considered, and then their more complex options, in which all nodes of the underfloor heating system will be calculated:In case of self-calculation, errors may occur. To avoid them and check the correctness of the calculations, you should use computer programs that contain correction factors. To calculate the warm floor, you need to select the interval of pipe laying, their diameter, as well as the material. The calculation error of the online program does not exceed 15%.
