Maximum size of the water heated floor circuit. Warm water floor - maximum pipeline length. To determine this parameter we must take into account
We continue to disassemble design of heated floors, started in the previous article, and now we will consider the main design recommendations.
What should the surface temperature of the heated floor be?
Actually, I already wrote about this in a separate article, but it would be worth repeating. Listed below maximum floor surface temperature limits for premises of various purposes:
- for living quarters and work rooms in which people mainly stand: 21...27 degrees;
- For living rooms and offices: 29 degrees;
- for lobbies, hallways and corridors: 30 degrees;
- for baths, swimming pools: 33 degrees
- for premises in which there is active work: 17 degrees
- in premises with limited presence of people ( industrial premises) a maximum floor temperature of 37 degrees is allowed.
In the edge zones up to 35 degrees.
What is the temperature of the coolant in the water heated floor system?
The supply water temperature should be between 40 and 55 degrees. The maximum temperature of the coolant at the entrance to the water heated floor system should not exceed +60 degrees.
The temperature difference of the coolant between the supply and return pipelines is optimal 5...15 degrees. Less than five degrees is not recommended due to the greatly increasing coolant flow through the circuit, which leads to large pressure losses. More than fifteen degrees is not recommended due to a noticeable difference in the temperature of the surface of the floor itself (in this case, under the windows we can have 27 degrees, at the end of the circuit 22 degrees, such a large difference is not comfortable). The optimal temperature drop is 10 degrees. Recommended temperatures at the inlet/outlet loops: 55/45 degrees, 50/40 degrees, 45/35 degrees, 40/30 degrees.
If thermal power is used as a heat source pumping unit(although this is very rare), it is advisable to set the temperature of the supply coolant to the heating circuit at 40 degrees. In all other cases, any other supply temperature within the above range can be used.
What should be the length of water heated floor pipes?
The maximum length of one circuit (loop) depends on the diameter of the pipes used:
- with a diameter of 16 mm - 70...90 meters;
- with a diameter of 17 mm – 90…100 m;
- diameter 20 mm – 120 m.
The difference in lengths is explained by different hydraulic resistance and thermal load of the pipes different diameters. Well, it’s clear: the thicker the pipe, the less hydraulic resistance it has (resistance to fluid flow).
Typically one circuit heats one room. But if the area of the room is large, the length of the circuit is longer than optimal, then it is better to make two circuits per room than to lay a pipe that is too long.
If during design and calculations you take one pipe diameter and then install another, then the hydraulics of the system will be different. So it is better and correctly to allow all experiments at the design and calculation stage, compare the results, choose the best one and follow it.
If two or more circuits are installed in a room, you should strive to ensure that their lengths are the same (the length of the circuit is the entire pipe, starting from the collector, and not just that part of it that is directly in the heated room itself).
Of course, in practice, it is impossible to adjust the length perfectly, but you need to strive for this and the difference should be no more than 10 m!
The rooms in the house, as you know, have different areas. To lay the same number of meters of pipe in a smaller room as in a larger one, you need to take a smaller step between turns.
If the room is small and the heat loss from it is not great (toilet, hallway), then you can combine the circuits and heat from the return pipe of the adjacent circuit.
At what step should the underfloor heating pipes be laid out?
The pitch (distance between adjacent turns of pipes) of pipe laying is from 15 to 30 cm (15, 20, 25, 30 cm - that is, not 21; 22.4; 27, etc., but with a step of 5 cm in the specified range 15-30 cm). Allowed pipe laying pitch is 30, 35, 40, 45 cm in large rooms(gyms, etc.). And 10 cm near large windows, external walls (in the so-called edge zones).
The pipe layout step is selected depending on the thermal load, type of room, circuit length, coating material, etc.:
- edge zones - 100…150 mm ( standard quantity rows in the edge zone - 6);
- central zones 200…300 mm;
- bathrooms, bathrooms, shower rooms, etc. are completely laid in increments of 100...150 mm. The same step may not be possible due to the need to bypass the plumbing and due to the cramped space in the room;
- in rooms where the floor will be covered with a material with good thermal conductivity ( tile, marble, porcelain stoneware) pipe laying pitch - 200 mm.
Attention! The above are the recommended numbers. In practice, it is often impossible to bend a metal-plastic pipe with a small radius without the danger of breaking it (when laid with a snake). Therefore, when laying with a snake, it is better and optimal to have a pitch of 150...200 mm. And in general, take note: despite any recommendations and clever justifications, make the pipe pitch in the edge zones 100 mm, and in the remaining 150 mm, and you will never go wrong.
A pitch of 300 mm will not provide uniform heating of the floor at all (again, when laying with a snake).
How to choose the diameter of pipes for underfloor heating systems?
IN residential buildings or apartments with an area ranging from 50 m2 to infinity - a pipe with a diameter of 16 mm is used. No need for more!
Even in well-insulated houses, it is desirable that the pipe pitch does not exceed 150, maximum 200 mm - and the 16th pipe makes it possible to meet all these conditions. In general, larger diameter pipes are not needed for a private home: they are optimal in terms of “ease of installation – price – coolant volume”.
Another pipe often used is 18 mm. However, you need to understand that a thicker pipe means extra costs, and not only for the pipe, but also for fittings and everything else.
Sometimes they lay a pipe with a diameter of 20 mm, without taking into account the characteristics. And in such a pipe the amount of water is already significantly greater, which is why heating will require more energy. And it’s difficult to install such a pipe: bending it for installation with a snake and a step of 150 mm is unrealistic, and a larger step will not provide heat in the house, and the cost of the coolant will be indecently decent. Such a pipe can be laid in some public buildings, with high ceilings, while simultaneously being there large number of people. There will be a thick screed poured in there! For a 16 mm pipe, the thickness of the screed is sufficient 50 mm from the top of the pipe. Up to 80 mm is allowed.
What should be the diameter of the pipes from the boiler to the collector?
The task is to connect one, two or more underfloor heating collectors.
Almost every underfloor heating collector has a 1-inch (25 mm) thread for connecting to the main line - it doesn’t matter whether it is internal or external.
There are manifolds with inch and a quarter threads, but these are for large industrial or public institutions, where a larger diameter pipe will be used, so there is NO need to take such collectors for a private house.
It makes no sense to initially narrow or “widen” the diameters of the main pipes (i.e., supplying coolant from the boiler), but it makes sense to take the same diameter as the collector inlet, i.e. 1 inch. For a polypropylene pipe, this is a diameter of 32 mm (this is the outer one, and the inner one is just 25 mm). For metal-plastic pipe this is a diameter of 26 mm. For copper – 28 mm. This - standard options on the use of pipes. But if there are doubts about the number of circuits, then you can increase the diameter of the main pipes by one size (40, 32 and 32 mm for polypropylene, metal-plastic and copper pipes respectively; To go 1 inch you will need an adapter).
Pipes made of cross-linked polyethylene (PEX) have the same dimensions as metal-plastic pipes in terms of wall thickness and diameters.
Other data for designing underfloor heating
It is not advisable to connect the concrete and deck systems to the same mixing unit (and manifold).
One circuit should be for one room (meaning, there is no need to get weird by laying out a loop, filling in the screed, and then dividing the room with a partition).
It is advisable to place the collector in the middle of the house. If this does not work, then the problem with the difference in loop lengths is solved by installing flow meters on the manifold: with their help, the uniform flow of coolant through loops of different lengths is regulated.
If the circuits are 90 m long (or even more), then a maximum of nine circuits can be “attached” to one collector. With loop lengths of 60...80 m, up to 11 loops can be mounted on one collector.
There is no need to “press” two (or more) collectors with one pump. It is correct to install separate pumps for each manifold group.
Mixing modules ( mixing units) not all are suitable for all pipe lengths of underfloor heating loops, so check when purchasing.
For an accurate calculation, it is necessary to take into account not only heat loss, but also the possible heat influx into the premises - for example, from operating equipment, household appliances, etc. (it hardly makes sense to fool around with this when calculating the heating of a private house), heat influx through the ceiling - if There is also a heated floor in the upper room. Calculation multi-storey buildings must be carried out starting from the premises of the upper floor to the lower ones. Because heat loss through the floor of the second floor is a useful heat gain for the premises of the first floor.
The thickness of the insulation on the first and ground floor not less than 50 mm (in reality, it depends on the climate zone: what is good for the south is not good at all in the north), on other floors - not less than 30 mm. A logical question: why insulate the ceiling between the first and second floors, even if the heat from the heated floor on the second floor also warms the first floor? Answer: if the floor is concrete, then insulation is installed so as not to heat the floor itself, because this is very expensive both in terms of money and time.
The maximum pressure loss in the circuit is 15 kPa (optimally 13 kPa). If the circuit has a pressure loss of more than 15 kPa, you need to reduce the coolant flow or divide the floor area in the room into several circuits. We’ll look at what this means in one of the following articles, when we perform calculations using a specific example.
Minimum consumption coolant in one circuit is at least 27-30 liters per hour. Otherwise, the contours need to be combined. Why such a restriction? At a lower flow rate, the coolant will not have time to pass through the entire circuit, but will have time to cool down - the floor will be cold! The minimum coolant flow on each circuit can be set on the control valve (flow meter) installed on the manifold.
The above requirements for design of heated floors will need to be taken into account when performing calculations for heated floors, when we do this in a special program. So, if these terms don’t mean anything to you yet, don’t worry, everything will fall into place in due time. However, I recommend making a note for yourself somewhere so that you can return to the information in this article when making calculations.
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Correct calculation is the key to success in any business. However, it is not so easy to implement all the plans in practice. This statement fully applies to conducting communications to create. You can calculate everything down to millimeters, but still checking the resulting data will be necessary at each stage of work, since it is impossible to fully take into account everything. In addition, each apartment has its own characteristics of the floor surface, so it is often difficult to take into account all the bends and depressions. However, do not despair, because installing a heated floor system correctly, although difficult, is possible.
How to position heating pipes
A water heated floor system consists of many elements, the main one of which is tubes that release heat under the floor of the entire house.Based on what is more convenient for the master, communications can be arranged in 4 options:
- Snake.
- Corner snake.
- Double snake.
- A snail.
Correct calculation heating system- a difficult task, but quite feasible with a step-by-step approach. It is problematic to take into account absolutely all the nuances when installing a heated floor, so it is worth paying attention to the most important characteristics, namely the length of the pipes and the volume of water in them. In addition, it is worth remembering that even a slight excess of the circuit length of 100 m can seriously harm the system and produce an output temperature that is far from the expected one. The double-circuit model, in turn, will be much more efficient, which will allow you to heat the house without much hassle and with less resource consumption.
Warm floor perfect solution to improve your home. The floor temperature directly depends on the length of the heated floor pipes hidden in the screed. The pipe in the floor is laid in loops. In fact, the total length of the pipe is determined by the number of loops and their length. It is clear that the longer the pipe in the same volume, the warmer the floor. In this article we will talk about restrictions on the length of one heated floor circuit.
Approximate design characteristics for pipes with a diameter of 16 and 20 mm are: 80-100 and 100-120 meters, respectively. These data are provided as approximate estimates. Let's take a closer look at the process of installing and pouring heated floors.
Consequences of exceeding the length
Let's figure out what consequences an increase in the length of the heated floor pipe can lead to. One of the reasons is an increase in hydraulic resistance, which will create additional load on the hydraulic pump, as a result of which it may fail or simply may not cope with the task assigned to it. The resistance calculation consists of many parameters. Conditions, installation parameters. The material of the pipes used. Here are the three main ones: loop length, number of bends and thermal load on it.
It is worth noting that the thermal load increases with increasing loop. The flow speed and hydraulic resistance also increase. There are restrictions on flow speed. It should not exceed 0.5 m/s. If we exceed this value, various noise effects may occur in the pipeline system. The main parameter for which this calculation is made also increases. Hydraulic resistance of our system. There are restrictions on it too. They amount to 30-40 kP per loop.
The next reason is that as the length of the heated floor pipe increases, the pressure on the walls of the pipe increases, causing this section to lengthen when heated. The pipe located in the screed has nowhere to go. And it will begin to narrow at its weakest point. The narrowing can cause blockage of the flow in the coolant. For pipes made from different material, different expansion coefficient. For example, at polymer pipes the expansion coefficient is very high. All these parameters must be taken into account when installing heated floors.
Therefore, it is necessary to fill the heated floor screed with pressed pipes. Pressure better with air with a pressure of approximately 4 bar. This way, when you fill the system with water and start heating it, the pipe in the screed will have room to expand.
Optimal pipe length
Taking into account all the above reasons, taking into account corrections for the linear expansion of the pipe material, we will take as a basis the maximum length of underfloor heating pipes per circuit:
The table shows the optimal dimensions for the length of a heated floor that are suitable for all modes of thermal expansion of pipes in various operating modes.
Note: In residential buildings, a 16 mm pipe is sufficient. A larger diameter should not be used. This will lead to unnecessary expenses for energy resources
One of the conditions for the implementation of high-quality and proper heating The purpose of a room using a heated floor is to maintain the temperature of the coolant in accordance with the specified parameters.
These parameters are determined by the project, taking into account the required amount of heat for the heated room and floor covering.
Required data for calculation
The efficiency of the heating system depends on a correctly laid circuit.
To maintain a given temperature regime indoors, it is necessary to correctly calculate the length of the loops used to circulate the coolant.
First, you need to collect the initial data on the basis of which the calculation will be performed and which consists of the following indicators and characteristics:
- temperature that should be above the floor covering;
- layout diagram of loops with coolant;
- distance between pipes;
- maximum possible pipe length;
- the ability to use several contours of different lengths;
- connection of several loops to one collector and to one pump and their possible number with such a connection.
Based on the listed data, you can correctly calculate the length of the heated floor circuit and thereby ensure a comfortable temperature regime in the room with minimal costs to pay for energy supply.
Floor temperature
The temperature on the surface of the floor, made with a water heating device underneath, depends on the functional purpose of the room. Its values should be no more than those indicated in the table:
Compliance with the temperature regime in accordance with the above values will create a favorable environment for work and rest for the people in them.
Pipe laying options used for heated floors
Options for laying heated floors
The laying pattern can be made with a regular, double and corner snake or snail. Various combinations of these options are also possible, for example, along the edge of the room you can lay out a pipe like a snake, and then the middle part - like a snail.
In large rooms with complex configurations, it is better to install it in a snail style. In rooms of small size and having a variety of complex configurations snake laying is used.
Pipe distance
The pipe laying pitch is determined by calculation and usually corresponds to 15, 20 and 25 cm, but no more. When laying out the pipes at intervals of more than 25 cm, a person’s foot will feel the temperature difference between and directly above them.
Along the edges of the room, the heating circuit pipe is laid in increments of 10 cm.
Allowable contour length
The length of the circuit must be selected according to the diameter of the pipe
This depends on the pressure in a particular closed loop and hydraulic resistance, the values of which determine the diameter of the pipes and the volume of liquid that is supplied to them per unit time.
When installing a heated floor, situations often occur when the circulation of the coolant in a separate loop is disrupted, which cannot be restored by any pump; the water is locked in this circuit, as a result of which it cools down. This results in pressure losses of up to 0.2 bar.
Based practical experience, you can adhere to the following recommended sizes:
- Less than 100 m can be a loop made from a metal-plastic pipe with a diameter of 16 mm. For reliability optimal size is 80 m.
- No more than 120 m is the maximum length of the contour of an 18 mm pipe made of cross-linked polyethylene. Experts try to install a circuit 80-100 m long.
- No more than 120-125 m is considered an acceptable loop size for metal-plastic with a diameter of 20 mm. In practice, they also try to reduce this length to ensure sufficient reliability of the system.
For more precise definition The size of the length of the loop for a heated floor in the room in question, in which there will be no problems with the circulation of the coolant, it is necessary to perform calculations.
Application of multiple contours of different lengths
The design of the floor heating system involves the implementation of several circuits. Of course, the ideal option is when all the loops are the same length. In this case, there is no need to configure and balance the system, but it is almost impossible to implement such a pipe layout. Detailed video For information on calculating the length of the water circuit, see this video:
For example, it is necessary to install a heated floor system in several rooms, one of which, say a bathroom, has an area of 4 m2. This means that heating it will require 40 m of pipe. It is impractical to arrange 40 m loops in other rooms, whereas 80-100 m loops can be made.
The difference in pipe lengths is determined by calculation. If it is impossible to perform calculations, you can apply a requirement that allows a difference in the length of the contours of the order of 30-40%.
Also, the difference in loop lengths can be compensated by increasing or decreasing the diameter of the pipe and changing the pitch of its installation.
Possibility of connection to one unit and pump
The number of loops that can be connected to one collector and one pump is determined depending on the power of the equipment used, the number of thermal circuits, the diameter and material of the pipes used, the area of the heated premises, the material of the enclosing structures and many other various indicators.
Such calculations must be entrusted to specialists who have knowledge and practical skills in carrying out such projects.
Loop size determination
The size of the loop depends on the total area of the room
Having collected all the initial data, having considered possible options creating a heated floor and having determined the most optimal one, you can proceed directly to calculating the length of the water heated floor circuit.
To do this, you need to divide the area of the room in which the loops for water floor heating are laid by the distance between the pipes and multiply by a factor of 1.1, which takes into account 10% for turns and bends.
To the result you need to add the length of the pipeline that will need to be laid from the collector to warm floor and back. Watch the answer to key questions about organizing a heated floor in this video:
You can determine the length of the loop laid in increments of 20 cm in a room of 10 m2, located at a distance of 3 m from the collector, by following these steps:
10/0.2*1.1+(3*2)=61 m.
In this room it is necessary to lay 61 m of pipe, forming a thermal circuit, to ensure the possibility of high-quality heating of the floor covering.
The presented calculation helps create conditions for maintaining comfortable temperature air in small separate rooms.
In order to correctly determine the pipe length of several heating circuits for a large number of rooms powered from one collector, it is necessary to involve a design organization.
She will do this with the help of specialized programs that take into account many different factors on which uninterrupted water circulation, and therefore high-quality floor heating, depends.
Today, the “warm floor” system is very popular among owners of apartments and private houses. The vast majority of those who have heating system, or has already done the installation similar design in his home, or is thinking about it. They are especially relevant in homes where there are small children who crawl and may freeze without adequate heating. These designs are much more economical than other heating systems. In addition, they interact better with the human body, since, unlike electric version do not create magnetic fluxes. Among them positive qualities fire safety and high efficiency. In this case, the heated air is evenly distributed throughout the room.
The principle is that lines are laid under the coating through which the coolant circulates - usually water, heating the floor surface and the room. This method is very effective at heating, provided correct calculation structure and if its installation is carried out correctly.
System installation options
There are two principles by which a warm water floor can be installed - flooring and concrete. In both options, insulation is necessarily used under the contour of the water floor - this is necessary so that all the heat goes up and warms the home. If insulation is not used, the space below will also be heated, which is completely unacceptable, since it reduces the heating effect. It is customary to use penoplex or penofol as insulation. Penoplex has excellent heat-insulating properties, repels moisture and does not lose its properties in a humid environment. It has good resistance to compression loads, is easy to use and inexpensive. Penofol also has a foil layer, which serves as a reflector of thermal radiation into the apartment.
The first option is to place the contour on a flooring made of insulation - polystyrene foam, penofol or other suitable material. We cover the contour from above with wood or other covering. The step-by-step process is as follows:
- We make a thin rough screed;
- We lay sheets of insulation with grooves for the main line;
- We lay the line and perform pressure testing;
- Cover the top with a backing made of foamed polyethylene or polystyrene;
- We put a finishing coating of laminate or other material with good thermal conductivity on top.
The second option looks like this step by step:
- We make a thin concrete screed;
- We put insulation on the screed;
- We lay waterproofing on the insulation, on top of which we place a contour of a warm water floor;
- We fix it along the top with reinforcing mm and fill it with concrete screed;
- Apply the finishing coating to the screed.
Temperature is controlled using two thermometers- one shows the temperature of the coolant entering the main, the other - the temperature of the return flow. If the difference is from 5 to 10 degrees Celsius, then the design is working normally.
Methods for laying the contour of a warm water floor
When we carry out installation, the highway can be laid out in the following ways:
For spacious rooms with a simple geometric configuration, it is worth using the snail method. For rooms small size complex shape It is more convenient and efficient to use the snake method.
These methods, of course, can be combined with each other.
depending on the diameter of the line and the size of the room. The smaller the installation step, the better and more efficiently the housing is heated, but on the other hand, then the costs of heating the coolant, materials and installation of the structure increase significantly. The maximum step size can be 30 centimeters, but this value cannot be exceeded, otherwise the human foot will feel the temperature difference. Near the outer walls, heat loss will be greater, so the pitch of laying the main in these places should be less than in the middle.
The material for making pipes is polypropylene or cross-linked polyethylene. If you are using polypropylene pipes, it is worth choosing an option with fiberglass reinforcement, since polypropylene tends to expand when heated. Polyethylene pipes When heated, they behave well and do not require reinforcement.
Water floor contour length
The length of the underfloor heating water circuit is calculated using the formula:
L=S\N*1,1, where
L - loop length,
S is the area of the heated room,
N - laying step length,
1.1 - pipe safety factor.
There is such a thing as maximum length water loop - if we exceed it, a loopback effect may occur. This is a situation when the coolant flow is distributed in the main in such a way that a pump of any power cannot set it in motion. The maximum loop size directly depends on the diameter of the pipe. As a rule, it ranges from 70 to 125 meters. The material from which the pipe is made also plays a role here.
The question arises - what to do if one circuit maximum size unable to heat the room? The answer is simple - we design a double-circuit floor.
Installation of a system where a double-circuit design is used is no different from that where a single circuit is used. If the double-circuit option does not cope with the task, we add required amount loops, how many can be connected to a homemade manifold for heated floors made of polypropylene.
The question arises - how much one circuit can differ in size from another in a design where there is more than one of them. In theory, the installation of a warm water floor structure assumes an equal distribution of the load and therefore it is desirable that the length of the loops be approximately the same. But this is not always possible, especially if one collector serves several rooms. For example, the size of the loop in the bathroom will be clearly smaller than in the living room. In this case, the balancing valve equalizes the load along the contours. Size variation in such cases is allowed up to 40 percent.
Installation of a warm water heating structure is allowed only in those areas of the room where there will be no large furniture. This is due to the excessive load on it and the fact that it is impossible to ensure proper heat transfer in these areas. This space is called usable area premises. Depending on this area, as well as on the laying step, the number of loops of the structure depends.
- 15 cm - up to 12 m2;
- 20 cm - up to 16 m2;
- 25 cm - up to 20 m2;
- 30 cm - up to 24 m 2.
Installation of heated floors - what else you need to know
When installing a water heating system, you should know a few more important things.
- One loop should heat one room - do not stretch it over two or more rooms.
- One pump must serve one manifold group.
- When calculating multi-storey buildings served by one collector, the coolant flow should be distributed starting from upper floors. In this case, the heat loss from the floor on the second floor will serve as additional heating for the premises on the first floor.
- One collector is able to service up to 9 loops with a circuit length of up to 90 m, and with a length of 60-70 m - up to 11 loops.
Conclusion
Warm water heating systems are extremely convenient and efficient to use. It is quite possible to install them yourself. A big role is played by the correctness of calculations, accuracy and thoroughness of all work, taking into account all the features and details. After all the work has been completed, you will be able to enjoy the warmth, coziness and comfort of a perfectly heated room with a floor that is so pleasant to walk on barefoot.
