The underfloor heating system can significantly increase the level of comfort in the home. The heat generated by the system is distributed in a comfortable zone for the owners and does not stimulate the movement of air with dust. If you have certain skills and knowledge, you can make a floor with a polyethylene pipeline yourself.
We will tell you how to use the most inexpensive material in arranging underfloor heating. In the article we presented, we discussed in detail how to correctly lay cross-linked polyethylene for a heated floor, with what step and according to what pattern to arrange it. Our tips will help you build a perfectly functioning system.
Cross-linked polyethylene is a variant of conventional ethylene, strengthened by chemical, physical or complex effects. Thanks to this procedure, in addition to the characteristic longitudinal bonds, transverse connections appear in the polymer structure.
As a result of production manipulations, polyethylene products achieve dimensional stability and acquire increased resistance to deformation and exposure to high temperatures. The processing process with the introduction of organic compounds into the polymer is called “cross-linking”.
Depending on the technology, it is performed either before or after extrusion. Long pipes in reels made of cross-linked polyethylene are used for arranging heating systems due to their high tightness - the risk of leaks is reduced to zero.
Technical characteristics of linear products made of cross-linked polyethylene:
- outer diameter 10-200 mm;
- wall thickness 2-5 mm;
- average specific gravity 110 g/linear m;
- density 949 kg/m3;
- deformation at temperatures above +200ºС, melting +4000ºС;
- average working pressure 6 MPa;
- average thermal conductivity – 0.4 W/mK.
Considering that the maximum temperature of the coolant is +90º C, and the pressure does not exceed 4 bar, we can conclude that pipes of this type are excellent for installing water heated floors.
Cost of 1 sq.m. underfloor heating made of cross-linked polyethylene is 1500-3500 rubles
In comparison with corrugated steel or copper pipes, also often used for heated floors, these products have the following advantages:
- Resistance to corrosion processes. The material is not subject to corrosion, exposure to aggressive environments, and does not deform under high acidity, alkalinity, or upon contact with organic substances.
- Excellent strength characteristics. Resistance to static and dynamic loads, resistance to tearing, bending, stretching, etc. Pipes can withstand low and high temperatures without damage.
- Stable throughput. There is no sediment deposited on the pipeline walls, which reduces the internal diameter of the pipes.
- Elasticity. Flexible pipes do not break when bent under any radius.
- Environmental safety. When heated, the product does not release toxins.
Step-by-step installation of heated floors
The technology of the device consists in the gradual creation of layers laid in a strict sequence. The total thickness of the system will be 10-20 cm, depending on the characteristics of the screed, the insulation and reinforcement used.
Preparatory work before construction
It should be borne in mind that the average load created by the “warm floor pie” on the concrete base is 300-350 kg/m2. Therefore, the floors must be designed for this weight.
When installing a heated floor using pipes made of cross-linked polyethylene, the following stages of work must be completed:
- Pipe selection. Calculation of the contour length. Drawing up a laying diagram.
- Preparing the base. Laying waterproofing and insulation.
- Installation of pipe circuits. Hydraulic tests.
- Filling the screed and finishing installation of the selected floor covering.
- Putting the system into operation.
When purchasing manifolds, it is better to give preference to devices with balancing valves and flow metering devices, which will simplify system setup in the future, and in the event of a malfunction, help to quickly identify the problematic circuit.
To build a heated water floor you will need the following:
- water heating boiler for heating the coolant;
- expansion tank;
- circulation pump for forced movement of coolant;
- plumbing fittings: fittings, ball valves;
- pipe reel made of cross-linked polyethylene;
- fasteners for insulation boards and PE pipes;
- distribution manifold unit;
- damper tape;
- insulation and reinforcing mesh;
- screed mortar or dry screed mixture.
All materials should be prepared in advance so that during the process of installing a heated floor you will not be distracted by shopping and purchasing additional components.
It is better to entrust the choice of distribution manifold to professionals or calculate it yourself using special calculator programs
Selecting and creating a pipe laying scheme
For residential premises, three laying patterns are used: “snake”, “shell” or “snail” and “double spiral”. A spiral “snail” is the simplest option, ensuring a uniform distribution of thermal energy. According to this scheme, water heated floors are most often built, because all angles in it are 90º.
Laying according to the “snake” pattern is somewhat more complicated, because it involves 180º turns. But it is excellent for constructing a system made of cross-linked polyethylene, because pipes made of this material bend freely, and the throughput in the loops is practically not reduced.
The choice of installation scheme depends entirely on the characteristics of the room. If we are talking about the arrangement of large-sized areas, installation is carried out according to the “double spiral” scheme. It is also used if it is planned to allocate zones according to heating intensity, for example in the hall, in front of the entrance or in front of a large terrace.
“Snail” guarantees uniform heating of the floor, “Snake” guarantees maximum temperature at the edge points of the room
For simple spiral and serpentine schemes, the optimal length of the circuit will be 60-80 m. For rooms where the length is much greater than the width, a circuit length of 100-120 m is permissible, but provided that larger diameter pipes are used.
The distance between the pipes (step) is 10-35 cm. The wider the step, the less heat will come from the floor.
At peak points, where the maximum heat loss is observed, the step width should be minimal, for example, near the front door it should be 10-15 cm, increasing as you approach the center of the room. The distance of the pipes from the walls along the perimeter is 30-45 cm.
If possible, the collector unit for heated floors is located in the center of the apartment (floor of a private house). This way, all points of the heating floor system will be supplied with coolant at approximately the same temperature. In areas of increased heat loss, near window and door openings, the pitch between pipes is reduced to increase heat transfer
Schemes and options for laying a heated water floor pipeline are described in detail, which we recommend that you familiarize yourself with.
Selection and calculation of the number of pipes
When choosing cross-linked PE pipes, you have to decide what diameter of the product is best to purchase. As practice shows, the best option for installing a heated floor in your own house or apartment located on the ground floor is a 16 mm pipe.
For rooms whose length is several times greater than their width, pipes of 20 or 25 mm can be used. The standard wall thickness is 2 mm.
To calculate the required number of polyethylene pipes, you can use the formula:
D=S/M x k
- D – design length of the pipe;
- S – area of the heated floor;
- M – average step selected according to the scheme;
- k – safety factor (for rooms up to 30 m2 is 1.1, more than 30 m2 – 1.4).
It should be remembered that the maximum length of a cross-linked polyethylene pipe depends on the diameter - the larger the diameter, the longer the coolant pipe can be. For products with a diameter of 16 mm - up to 90 m, 20 mm - 120 m, 25 mm - 150 m.
Too long pipes with a small diameter increase the risk of problems with coolant circulation
You will learn how to perform a complete test, including determining heat loss and the power of circulation equipment, from our recommended article.
Preparing the base for pipes
When the calculations for the required number of pipes are completed, you can proceed to preparing the base for the water-heated floor circuit.
This stage includes the following workflows:
- removal of old flooring and old screed;
- laying the insulating layer;
- installation of insulation;
- laying reinforcing mesh;
- damper tape sticker.
First you need to level the base so that the differences are no more than 5 degrees (we check with a building level). For leveling, you can use a sand mixture followed by compaction or self-leveling compounds. The leveled base is removed from dust and debris.
Then the waterproofing layer will be laid. The simplest type is plastic film.
If you have financial capabilities, it is better to use high-quality Russian or European waterproofing in the form of a polymer membrane. It not only reliably protects the floor from moisture, but also allows the warm floor system to “breathe”.
To increase the parameters for heat conservation, the vapor barrier can be laid on foil insulation-heat reflector
Next comes waterproofing, which can be used as extruded polystyrene foam. This is the cheapest and most effective way to reduce heat loss.
Of the new insulation materials, cork insulation is considered the most environmentally friendly, but its cost is tens of times higher than that of the most expensive polystyrene foam. Insulation boards 5 cm thick are attached to wooden guide rails using dowel nails. The plates are fastened together with glue and special staples.
As for the reinforcing mesh, when using polystyrene foam boards there is no need to lay it - the pipeline is laid directly on the insulation. The use of mesh is justified if another layer of waterproofing is laid on top of the insulation.
If you don’t want to overpay for insulation, then you need to keep in mind that there are special insulation blocks for sale for installing heated floors, which have channels for pipes. Such blocks significantly increase the cost of creating a heated floor, but they are very convenient to use.
After the mesh layer, it’s time to stick on the compensating damper tape. This is done simply - foam tape is glued around the perimeter of the room, which compensates for the expansion of the future concrete screed. Instead of damper tape, you can use even pieces of polystyrene foam.
After preparing the base, the heating boiler and manifold distribution unit are installed. The boiler is connected to the water supply and power supply system (gas or electricity).
Special insulation for heated floors has gaps for pipes and markings for their correct installation
Information about the ones used in the installation of water heated floors is provided in detail by the following article, which we recommend reading before planning installation.
Installation of polyethylene pipes
The heated floor is laid using contours according to a pre-selected pattern. The circuit is a closed ring of pipe, which, upon returning to the manifold, is connected to it using a fitting.
For small rooms, 1-3 circuits are installed. To simplify installation, it is recommended to apply approximate markings to the polystyrene foam boards. If there are markings, it will be easier for you to lay polyethylene pipes and check the step size.
Before starting, it is also necessary to decide how the pipes will be connected and how the polyethylene pipes will be attached to the insulation.
The fact is that pipe connections can be made:
- welding;
- compression fittings;
- press fittings.
The last option is the easiest to implement and most reliable. To connect the pipes, it is necessary to install a movable coupling, and then use an expander to carefully increase the internal diameter of the pipe to the required size.
Fasten the fitting until it stops and push the sleeve over the pipe. The compression joint can withstand prolonged exposure to high temperatures and pressures up to 10 MPa.
As for the method of attaching polyethylene pipes to the insulation, this is relevant if regular polystyrene foam is used.
There are several mounting options:
- polyethylene tightening clamps;
- steel wire;
- fasteners secured with a stapler;
- fixing tracks.
The simplest and most economical method of fastening is with clamps. Consumption is 2 pieces per 1-1.5 m.
On straight sections, fastening clamps are installed every 30-50 cm, and on bends - 10-20 cm
There are 10 rules for installing cross-linked polyethylene for heated floors:
- When laying bends, sharp creases of the material are not allowed.
- Installation work is carried out at a temperature not lower than +18 C.
- After bringing the pipe in from the cold, you must wait until it warms up to room temperature.
- The maximum turning radius for pipes with a diameter of 16 mm should be 10-12 cm.
- During the installation process, it is not advisable to change the selected layout of the coolant.
- Trimming the excess length should be carried out immediately before connecting it to the distribution manifold.
- Do not step on, place heavy things, or place instruments on pipes.
- To move along laid pipes (if necessary), it is recommended to use large sheets of plywood to reduce the load on the coolant.
- To increase the heat retention rate, the pipes coming out from under the floor at the point of connection to the collector unit can be reinforced with thermal insulation.
- The pipes should lie flat, without twisting or excess tension.
After laying the circuit, the pipe returns to the manifold and is connected using a fitting selected to size. After this, the system is tested, the purpose of which is to detect defects before the system is hidden under the screed.
To carry out the tests, you will need a household compressor that can produce a pressure of 4-6 bar. The coolant is supplied into the pipes using a compressor and left for 6-12 hours. When the fastening clamps are removed, they must be reapplied 5 cm below the previous attachment point.
Screed rules
If the hydraulic tests are completed successfully, no depressurization of the pipes has occurred, and the system is completely filled with coolant, then the pipe installation stage is completed. Now you can begin installing the screed and finishing.
To do this, you need to use a purchased or self-prepared mortar based on M300 cement. The minimum screed height to protect polyethylene pipes is 3 cm above the laid pipe. This thickness will be optimal for uniform heat distribution.
In most cases, the screed is made continuous without expansion joints. Thermal seams are necessary when:
- the room has an area of more than 33 m2;
- room length more than 10 m;
- the room has a complex configuration.
Damper tape is used to create seams. Thermal joints are treated with sealant.
Is it necessary to do reinforcement before pouring the screed? There is no clear answer to this question. Experience shows that the system functions perfectly without reinforcement, but at the same time, the reinforcing layer gives the screed additional strength. For reinforcement, you can use a 100x100 mm mesh made of metal or plastic.
Also, reinforcement will be useful only if the reinforcing mesh does not just lie on top of the pipe system, but “sinks” into the solution, being inside the screed when it hardens.
The correct reinforcement device complicates the laying of the screed, therefore, when there is no experience or confidence that everything can be done correctly, this stage can be skipped. After pouring the screed, the system can be started no earlier than 25-30 days later.
Any floor covering can be used as a final finish – the top layer of the “pie”.
Commissioning of the system
After final hardening, the poured screed can be fed into the system, the temperature of which should not exceed +26ºС.
The algorithm for commissioning a heated floor system made of cross-linked polyethylene is as follows:
- connect to the supply and return pipelines;
- we open all circuits simultaneously using taps on the manifolds;
- We install the air vent valves in the “open” position;
- start the circulation pump;
- set the temperature to +25-26º C;
- raise the pressure in the system to working 1 bar;
- we close all circuits except the longest with taps;
- record all positions of flow meters and balancers;
- We open the next circuit in length and use a tap to equalize the pressure along the first circuit.
In this way we connect and balance all the circuits of the heated floor. The performance of the heating can be assessed only after 2-3 months of operation.
With features and rules for installing floor heating on a wooden base, describing in detail the rules for designing and constructing the system.
Conclusions and useful video on the topic
A correctly selected and installed heated floor will make your home warm and comfortable without any special expenses. The technology for constructing an underfloor heating circuit made of PE pipes is simple and can be used not only by professional builders, but also by ordinary people. If you follow all the rules and recommendations, the system will serve you well for a long time.
Have you ever had to lay polyethylene pipes when installing a heated floor? Perhaps you know some technological nuances that are not mentioned in the article? Please write 0 comments, ask questions, post photos on the topic in the block below.
Despite the complexity of installation, underfloor heating using a water circuit is considered one of the most cost-effective methods of heating a room. In order for the system to function as efficiently as possible and not cause failures, it is necessary to correctly calculate the pipes for heated floors - determine the length, loop pitch and circuit laying pattern.
The comfort of using water heating largely depends on these indicators. It is these questions that we will examine in our article - we will tell you how to choose the best option for pipes, taking into account the technical characteristics of each type. Also, after reading this article, you will be able to choose the correct installation step and calculate the required diameter and length of the heated floor contour for a specific room.
At the design stage, it is necessary to resolve a number of issues that determine the heated floor and the operating mode - select the thickness of the screed, the pump and other necessary equipment.
The technical aspects of organizing a heating branch largely depend on its purpose. In addition to the purpose, to accurately calculate the footage of the water circuit, you will need a number of indicators: coverage area, heat flux density, coolant temperature, type of floor covering.
Pipe coverage area
When determining the dimensions of the base for laying pipes, take into account the space that is not cluttered with large equipment and built-in furniture. It is necessary to think in advance about the arrangement of objects in the room.
If a water floor is used as the main heat supplier, then its power should be enough to compensate for 100% of heat losses. If the coil is an addition to the radiator system, then it must cover 30-60% of the heat energy costs of the room
Heat flow and coolant temperature
Heat flux density is a calculated indicator characterizing the optimal amount of heat energy for heating a room. The value depends on a number of factors: thermal conductivity of walls, ceilings, glazing area, presence of insulation and air exchange rate. Based on the heat flow, the loop laying step is determined.
The maximum coolant temperature is 60 °C. However, the thickness of the screed and the floor covering reduce the temperature - in fact, about 30-35 ° C is observed on the floor surface. The difference between the temperature indicators at the input and output of the circuit should not exceed 5 °C.
Type of flooring
The finish affects the efficiency of the system. Optimal thermal conductivity of tiles and porcelain stoneware - the surface heats up quickly. A good indicator of the efficiency of the water circuit when using laminate and linoleum without a thermal insulation layer. Wooden coverings have the lowest thermal conductivity.
The degree of heat transfer also depends on the filling material. The system is most effective when using heavy concrete with natural aggregate, for example, fine sea pebbles.
The cement-sand mortar provides an average level of heat transfer when the coolant is heated to 45 °C. The efficiency of the circuit drops significantly when installing a semi-dry screed
When calculating pipes for heated floors, you should take into account the established standards for the temperature regime of the coating:
- 29 °C– living room;
- 33 °C– rooms with high humidity;
- 35 °C– passage zones and cold zones – areas along the end walls.
The climatic features of the region will play an important role in determining the density of the water circuit. When calculating heat loss, the minimum temperature in winter must be taken into account.
As practice shows, preliminary insulation of the entire house will help reduce the load. It makes sense to first thermally insulate the room, and then start calculating heat loss and parameters of the pipe circuit.
Assessment of technical properties when choosing pipes
Due to non-standard operating conditions, high demands are placed on the material and size of the water floor coil:
- chemical inertness, resistance to corrosion processes;
- Absolutely smooth internal coating, not prone to the formation of limescale build-up;
- strength– the walls are constantly exposed to the coolant from the inside, and the screed from the outside; the pipe must withstand a pressure of up to 10 bar.
It is desirable that the heating branch have a small specific gravity. The water floor pie already places a significant load on the ceiling, and a heavy pipeline will only worsen the situation.
According to SNiP, the use of welded pipes in closed heating systems is prohibited, regardless of the type of seam: spiral or straight
Three categories of rolled pipes meet the listed requirements to one degree or another: cross-linked polyethylene, metal-plastic, and copper.
Option #1 – cross-linked polyethylene (PEX)
The material has a mesh wide-cell structure of molecular bonds. Modified polyethylene differs from conventional polyethylene in the presence of both longitudinal and transverse ligaments. This structure increases specific gravity, mechanical strength and chemical resistance.
A water circuit made of PEX pipes has a number of advantages:
- high elasticity, allowing the installation of a coil with a small bend radius;
- safety– when heated, the material does not emit harmful components;
- heat resistance: softening – from 150 °C, melting – 200 °C, combustion – 400 °C;
- maintains structure during temperature fluctuations;
- resistance to damage– biological destroyers and chemical reagents.
The pipeline retains its original throughput - no sediment is deposited on the walls. The estimated service life of a PEX circuit is 50 years.
The disadvantages of cross-linked polyethylene include: fear of sunlight, the negative effects of oxygen when it penetrates inside the structure, the need for rigid fixation of the coil during installation
There are four product groups:
- PEX-a – peroxide cross-linking. The most durable and uniform structure with a bond density of up to 75% is achieved.
- PEX-b – silane cross-linking. The technology uses silanides - toxic substances that are unacceptable for household use. Manufacturers of plumbing products replace it with a safe reagent. Pipes with a hygienic certificate are acceptable for installation. Crosslink density – 65-70%.
- PEX-c – radiation method. Polyethylene is irradiated with a stream of gamma rays or an electron. As a result, the bonds are compacted up to 60%. Disadvantages of PEX-c: unsafe use, uneven crosslinking.
- PEX-d – nitriding. The reaction to create a network occurs due to nitrogen radicals. The output is a material with a crosslink density of about 60-70%.
The strength characteristics of PEX pipes depend on the method of cross-linking polyethylene.
If you decided on cross-linked polyethylene pipes, we recommend that you familiarize yourself with underfloor heating systems made from them.
Option #2 – metal-plastic
The leader in rolled pipes for installing heated floors is metal-plastic. Structurally, the material includes five layers.
The inner coating and outer shell are high-density polyethylene, which gives the pipe the necessary smoothness and heat resistance. Intermediate layer – aluminum spacer
The metal increases the strength of the line, reduces the rate of thermal expansion and acts as an anti-diffusion barrier - it blocks the flow of oxygen to the coolant.
Features of metal-plastic pipes:
- good thermal conductivity;
- ability to maintain a given configuration;
- operating temperature with preservation of properties – 110 °C;
- low specific gravity;
- noiseless movement of the coolant;
- safety of use;
- corrosion resistance;
- service life – up to 50 years.
The disadvantage of composite pipes is the inadmissibility of bending about the axis. Repeated twisting risks damaging the aluminum layer. We recommend that you familiarize yourself with metal-plastic pipes, which will help avoid damage.
Option #3 – copper pipes
In terms of technical and operational characteristics, yellow metal will be the best choice. However, its demand is limited by its high cost.
Compared to synthetic pipelines, the copper circuit wins on several points: thermal conductivity, thermal and physical strength, unlimited bending variability, absolute impermeability to gases
In addition to being expensive, copper piping has an additional disadvantage - complexity. To bend the contour you will need a press machine or.
Option #4 – polypropylene and stainless steel
Sometimes a heating branch is created from polypropylene or stainless steel corrugated pipes. The first option is affordable, but quite rigid in bending - the minimum radius is eight times the diameter of the product.
This means that pipes with a standard size of 23 mm will have to be placed at a distance of 368 mm from each other - an increased laying step will not ensure uniform heating.
Stainless steel pipes are characterized by high thermal conductivity and good flexibility. Disadvantages: fragility of sealing rubber bands, creation of strong hydraulic resistance by corrugation
Possible ways to lay out the contour
In order to determine the pipe consumption for arranging a heated floor, you should decide on the layout of the water circuit. The main task of planning the layout is to ensure uniform heating, taking into account the cold and unheated areas of the room.
The following layout options are possible: snake, double snake and snail. When choosing a scheme, you need to take into account the size, configuration of the room and the location of the external walls
Method #1 – snake
The coolant is supplied to the system along the wall, passes through the coil and returns to. In this case, half of the room is heated with hot water, and the rest with cooled water.
When laying with a snake, it is impossible to achieve uniform heating - the temperature difference can reach 10 ° C. The method is applicable in narrow spaces.
The corner snake design is optimal if you need to maximally insulate a cold zone near the end wall or in the hallway
The double snake allows for a softer temperature transition. The forward and reverse circuits run parallel to each other.
Method #2 – snail or spiral
This is considered the optimal scheme to ensure uniform heating of the floor covering. Direct and reverse branches are laid alternately.
An additional advantage of the “shell” is the installation of a heating circuit with a smooth bend rotation. This method is relevant when working with pipes of insufficient flexibility.
For large areas, a combined scheme is implemented. The surface is divided into sectors and a separate circuit is developed for each, leading to a common collector. In the center of the room the pipeline is laid out like a snail, and along the outer walls - like a snake.
We have another article on our website in which we examined heated floors in detail and provided recommendations for choosing the best option depending on the characteristics of a particular room.
Pipe calculation method
In order not to get confused in the calculations, we suggest dividing the solution to the problem into several stages. First of all, it is necessary to estimate the heat loss of the room, determine the laying step, and then calculate the length of the heating circuit.
Principles of circuit design
When starting calculations and creating a sketch, you should familiarize yourself with the basic rules for the location of the water circuit:
- It is advisable to lay pipes along the window opening - this will significantly reduce the heat loss of the building.
- The recommended coverage area of one water circuit is 20 square meters. m. In large rooms it is necessary to divide the space into zones and lay a separate heating branch for each.
- The distance from the wall to the first branch is 25 cm. The permissible pitch of pipe turns in the center of the room is up to 30 cm, along the edges and in cold zones – 10-15 cm.
- Determining the maximum pipe length for underfloor heating should be based on the diameter of the coil.
For a circuit with a cross-section of 16 mm, no more than 90 m is allowed, the limit for a pipeline with a thickness of 20 mm is 120 m. Compliance with the standards will ensure normal hydraulic pressure in the system.
The table shows the approximate pipe flow rate, depending on the loop pitch. To obtain more accurate data, you should take into account the turning margin and the distance to the collector
Basic formula with explanations
The length of the heated floor contour is calculated using the formula:
L=S/n*1.1+k,
- L– the required length of the heating main;
- S– covered floor area;
- n– laying step;
- 1,1 – standard factor of ten percent bending reserve;
- k– distance of the collector from the floor – the distance to the supply and return circuit wiring is taken into account.
The coverage area and the pitch of the turns will play a decisive role.
For clarity, on paper you need to draw up a floor plan indicating the exact dimensions and indicate the passage of the water circuit
It should be remembered that placing heating pipes under large household appliances and built-in furniture is not recommended. The parameters of the designated items must be subtracted from the total area.
To select the optimal distance between the branches, it is necessary to carry out more complex mathematical manipulations, operating with the heat loss of the room.
Thermal engineering calculation with determination of the circuit pitch
The density of the pipes directly affects the amount of heat flow emanating from the heating system. To determine the required load, it is necessary to calculate the heat costs in winter.
Thermal costs through the structural elements of the building and ventilation must be fully compensated by the generated heat energy of the water circuit
The power of the heating system is determined by the formula:
M=1.2*Q,
- M– circuit performance;
- Q– total heat loss of the room.
The value of Q can be decomposed into components: energy consumption through the enclosing structures and costs caused by the operation of the ventilation system. Let's figure out how to calculate each of the indicators.
Heat loss through building elements
It is necessary to determine the heat energy consumption for all enclosing structures: walls, ceilings, windows, doors, etc. Calculation formula:
Q1=(S/R)*Δt,
- S– area of the element;
- R– thermal resistance;
- Δt– the difference between the temperature indoors and outdoors.
When determining Δt, the indicator for the coldest time of the year is used.
Thermal resistance is calculated as follows:
R=A/Kt,
- A– layer thickness, m;
- CT– thermal conductivity coefficient, W/m*K.
For combined elements of a structure, the resistance of all layers must be summed up.
The thermal conductivity coefficient of building materials and insulation can be taken from a reference book or looked at in the accompanying documentation for a specific product.
We have provided more values of the thermal conductivity coefficient for the most popular building materials in the table contained.
Ventilation heat loss
To calculate the indicator, the formula is used:
Q2=(V*K/3600)*C*P*Δt,
- V– volume of the room, cubic meters. m;
- K– air exchange rate;
- C– specific heat capacity of air, J/kg*K;
- P– air density at normal room temperature – 20 °C.
The air exchange rate of most rooms is equal to one. The exception is for houses with internal vapor barrier - to maintain a normal microclimate, the air must be renewed twice an hour.
Specific heat capacity is a reference indicator. At standard temperature without pressure, the value is 1005 J/kg*K.
The table shows the dependence of air density on ambient temperature under atmospheric pressure conditions - 1.0132 bar (1 Atm)
Total heat loss
The total amount of heat loss in the room will be equal to: Q=Q1*1.1+Q2. Coefficient 1.1 – an increase in energy costs by 10% due to air infiltration through cracks and leaks in building structures.
Multiplying the obtained value by 1.2, we obtain the required power of the heated floor to compensate for heat loss. Using a graph of heat flow versus coolant temperature, you can determine the appropriate pipe pitch and diameter.
The vertical scale is the average temperature regime of the water circuit, the horizontal scale is the indicator of heat energy production by the heating system per 1 sq. m
The data is relevant for heated floors on a sand-cement screed with a thickness of 7 mm, the coating material is ceramic tiles. For other conditions, values must be adjusted to account for the thermal conductivity of the finish.
For example, when laying carpet, the coolant temperature should be increased by 4-5 °C. Each additional centimeter of screed reduces heat transfer by 5-8%.
Final choice of contour length
Knowing the pitch of laying the coils and the area covered, it is easy to determine the flow rate of the pipes. If the obtained value is greater than the permissible value, then it is necessary to install several circuits.
It is optimal if the loops are the same length - there is no need to adjust or balance anything. However, in practice, it is more often necessary to rupture the heating main into different sections.
The spread of contour lengths should remain within 30-40%. Depending on the purpose and shape of the room, you can “play” with the loop pitch and pipe diameters
A specific example of calculating a heating branch
Let's assume that you need to determine the parameters of the thermal circuit for a house with an area of 60 square meters.
For the calculation you will need the following data and characteristics:
- room dimensions: height – 2.7 m, length and width – 10 and 6 m, respectively;
- The house has 5 metal-plastic windows of 2 sq. m;
- external walls - aerated concrete, thickness - 50 cm, Kt = 0.20 W/mK;
- additional wall insulation – polystyrene foam 5 cm, Kt=0.041 W/mK;
- ceiling material – reinforced concrete slab, thickness – 20 cm, Kt=1.69 W/mK;
- attic insulation – 5 cm thick polystyrene foam boards;
- dimensions of the entrance door - 0.9 * 2.05 m, thermal insulation - polyurethane foam, layer - 10 cm, Kt = 0.035 W/mK.
Step 1 - calculation of heat loss through structural elements
Thermal resistance of wall materials:
- aerated concrete: R1=0.5/0.20=2.5 sq.m*K/W;
- expanded polystyrene: R2=0.05/0.041=1.22 sq.m*K/W.
The thermal resistance of the wall as a whole is: 2.5 + 1.22 = 3.57 sq. m*K/W. We take the average temperature in the house to be +23 °C, the minimum temperature outside is 25 °C with a minus sign. The difference in indicators is 48 °C.
Calculation of the total wall area: S1=2.7*10*2+2.7*6*2=86.4 sq. m. From the obtained indicator it is necessary to subtract the size of the windows and doors: S2 = 86.4-10-1.85 = 74.55 sq. m. m.
Substituting the obtained indicators into the formula, we obtain wall heat loss: Qc=74.55/3.57*48=1002 W
By analogy, heat costs through windows, doors and ceilings are calculated. To assess energy losses through the attic, the thermal conductivity of the flooring material and insulation is taken into account
The final thermal resistance of the ceiling is: 0.2/1.69+0.05/0.041=0.118+1.22=1.338 sq. m*K/W. Heat loss will be: Qp=60/1.338*48=2152 W.
Ro=0.56*0.1+0.5*0.9=0.56 sq.m*K/W. Here 0.1 and 0.9 are the proportion of each material in the window structure.
Window heat loss: Qо=10/0.56*48=857 W.
Taking into account the thermal insulation of the door, its thermal resistance will be: Rd=0.1/0.035=2.86 sq. m*K/W. Qd=(0.9*2.05)/2.86*48=31 W.
The total heat loss through the enclosing elements is: 1002+2152+857+31=4042 W. The result must be increased by 10%: 4042*1.1=4446 W.
Step 2 - heat for heating + general heat loss
First, let's calculate the heat consumption for heating the incoming air. Room volume: 2.7*10*6=162 cubic meters. m. Accordingly, ventilation heat loss will be: (162*1/3600)*1005*1.19*48=2583 W.
According to these room parameters, the total heat costs will be: Q=4446+2583=7029 W.
Step 3 - required power of the thermal circuit
We calculate the optimal circuit power required to compensate for heat loss: N=1.2*7029=8435 W.
Based on the required performance of the heating system and the active area of the room, it is possible to determine the heat flux density per 1 sq. m
Step 4 - determining the laying pitch and contour length
The resulting value is compared with the dependence graph. If the coolant temperature in the system is 40 °C, then a circuit with the following parameters is suitable: pitch – 100 mm, diameter – 20 mm.
If water heated to 50 °C circulates in the main, then the interval between branches can be increased to 15 cm and a pipe with a cross-section of 16 mm can be used.
We calculate the length of the contour: L=60/0.15*1.1=440 m.
Separately, it is necessary to take into account the distance from the collectors to the heating system.
Conclusions and useful video on the topic
Visual video reviews will help you make a preliminary calculation of the length and pitch of the thermal circuit.
Choosing the most effective distance between branches of an underfloor heating system:
A guide on how to find out the length of the loop of the heated floor in use:
The calculation method cannot be called simple. At the same time, many factors affecting the circuit parameters should be taken into account. If the water floor is planned to be used as the only source of heat, then it is better to entrust this work to professionals - mistakes at the planning stage can be costly.
Do you calculate the required footage of pipes for heated floors and their optimal diameter yourself? Maybe you still have questions that we did not cover in this material? Ask them to our experts in the comments section.
If you specialize in calculating pipes for arranging water heated floors and you have something to add to the material presented above, please write your comments below under the article.
If a decision has been made to install a heated floor system in the house, then it is not enough to simply buy the required materials - you also need to know how much of them will be needed. And these calculations are not easy, considering that you want not to buy too much and at the same time make sure that the purchased materials will be enough to achieve the required temperature level in the rooms. How to calculate a heated floor? Let's try to figure it out.
To begin with, I would like to dwell on what a correct and high-quality heated floor should be, regardless of what coolant - electricity or water - it will work on. So, such a heating system will work differently depending on the thickness of the base or the quality of the heat insulator, which means that all these points must be taken into account. It is believed that the thickness of the thermal insulation material should not be more than 3 cm, and it is better to purchase the material with a reflective layer - this will make it easier to retain heat indoors.
Advice! It is recommended to purchase polystyrene foam with a density of about 35 kg/m 3 as a heat insulator.
The thickness of the concrete screed should be about 4-10 cm, especially if we are talking about laying a cable or water floor. Inside, it is reinforced with a reinforcing mesh, onto which, by the way, coolants can be attached. Due to this, heat will be redistributed better. If you plan to install a water floor, it is recommended to purchase pipes made of metal-plastic or cross-linked polyethylene with a diameter of 16-20 mm - with them it is easiest to provide the system with optimal power sufficient to warm up the rooms.
What factors should you consider?
In order to make all the necessary calculations that will help determine the amount of materials for a heated floor, you should consider the following:
- the total area of the room where floor heating will be installed. The number of circuits in the system will depend on this figure;
Important! One heating circuit effectively heats a maximum of 40 m2. Moreover, its length should not be more than 100 m. And the step between laid pipes should not be more than 30 cm.
- number of collectors. It is important to remember that each heating circuit can only be connected to one manifold;
- layout of rooms where heating is installed;
- sizes of windows and other places where heat will be lost. Type of glazing. Types of doors;
- may affect the power indicator thickness of the walls of the house;
- indoor air humidity;
- arrangement of furniture and other interior items in the room. Under them, a heated floor is not installed if it is electric, since ventilation will be insufficient and the system may be damaged. And excessive heating can also have a negative effect on the safety of furniture and equipment;
- purpose of the room where installation will be carried out. Depending on this, the heating power is selected;
- other heat sources and their power.
The temperature regime in the region and the need to heat a specific room and regulate the temperature in it may be important. The type of floor finish can also have a significant impact on the power of the floor - some materials easily transmit thermal energy, others - worse.
Determining the desired temperature in the rooms
The final floor temperature depends on the purpose for which the room is used. For example:
- +29-30 degrees – halls, hallways;
- +27-29 – offices, living rooms;
- +30-35 – floors near windows, on verandas;
- +32 – bathrooms, toilets;
- +17-19 – gyms.
In this case, the coolant temperature should not be less than +40 degrees or exceed +60. The heating system should be such that the difference between the temperature indicators of the forward and return pipes in the case of water floors does not exceed 15 degrees. Otherwise, the base will be heated completely unevenly.
The balance of thermal/hydraulic loads for a water floor must also be optimal and adjusted. Therefore, the heating circuits must have a certain length in accordance with the diameter. The optimal pipe option is 18 mm, since even with a small amount of water such a pipeline will work correctly and heat the base.
Calculation of heat losses
Typically, underfloor heating systems do not act as the only source of space heating, but some plan to heat the house this way. But before making this engineering decision, it is important to make sure whether a particular room can be heated only in this way.
If during the period of use of the system, heat loss does not exceed 100 W/m2, then the floor heating system will be quite sufficient to warm up the room. However, it is quite difficult to make calculations on your own to obtain the necessary data, since complex formulas are used. So it is recommended to use an online calculator for calculating the heat loss of a room. If heat loss exceeds 100 W/m2, then the thermal insulation of the room must be improved or an additional heating system must be installed.
Calculation for different types of premises
Each room, depending on its characteristics, requires different floor heating power. It should be greatest in cool rooms, as well as on a loggia or balcony. In such a room, the power cannot be less than 180 W/m2. In a bathroom or toilet - at least 140 W/m2 due to high humidity levels.
Note! The power of the underfloor heating system cannot be low if there are unheated rooms under the room being equipped.
As for the electric floor, in this case the minimum power should be 120 W/m2.
Table. The power of the floor heating system when used as an additional heat source.
How to calculate electric floor heating
In general, a floor heating system consists of several elements. This is a thermostat that helps control the level of heating of the floors, a temperature sensor that monitors how hot the floors are, a heating element, as well as a power cable for connecting all this equipment to the electrical network.
The thermostat is usually installed on the wall, with all the wires connected to it. The heated floor itself, as well as the temperature sensor, are installed under the floor covering (in the screed or on its surface, depending on the type of system - heating mat, IR film or heating cable).
Note! The easiest way is to install infrared floors or heating mats. They can be laid simply under the floor covering. But the electrical cable will have to be covered with a screed. Yes, and the pitch between the wires in this case will have to be calculated independently.
To install cable heating, a single or two-core cable is used. The first is the simplest, but at the same time difficult to work with, although cheap. It will be quite difficult to calculate all the parameters for it, since both ends of the cable need to be brought out to one place. And an extensive electromagnetic field is formed from it.
It’s easier to buy a two-core cable, which, although it costs a little more, is still easy to install and operate due to the special arrangement of the wires.
Calculation formulas for electric floors
It is easy to determine the power of a warm electric floor system. To do this, the power of 1 m 2 of the selected system is sufficient to multiply by the area that it will heat. By the way, in the purchased kit the amount of cable used is already measured and marked. The distance between the turns of wires should be 5-20 cm. It can be calculated accurately using the formula h = Shx100/L, where h is the desired value of the step width, L is the length of the cable, and S is the area of the room.
How to calculate a warm water floor
Let's see how many materials are needed to install a water heating system in the room. The calculation of the number of pipes per 1 m2 in this case is done as follows: you need to find out how much heat loss in the room will be. The easiest way to determine them is with the help of an online calculator, which includes data about the building itself, as well as weather conditions outside. Let them be equal to 80 W/m2. Let's take the area of the apartment where the heated floor system will be installed equal to 80 m2. As a result, the total heat loss can be found by multiplying two values 80x80 = 6400 W. It is this value that will have to be compensated using all heating systems with a power reserve of up to 20%.
Table. Pipe calculation depending on the loop pitch.
| Step, cm | Consumption, m./1 sq. m. |
|---|---|
| 10 | 10 |
| 15 | 6,7 |
| 20 | 5 |
| 25 | 4 |
| 30 | 3,4 |
Typically, the distance between water lines is maintained at about 15 cm with a pipe cross-section of 16 mm. Then the power of 1 m 2 of floor will be about 100 W. Dividing the total area of the room by the step size, we get: 80/0.15 = 533 m. This is exactly how many meters of pipe will be required to install a water heating system in this apartment. The length of each contour is calculated in approximately the same way.
Attention! Near the walls of the room adjacent to the street, the step will be slightly smaller (10 cm). Taking this into account, the footage of the water pipeline is calculated.
In construction stores, pipes of a certain length are available for sale - from 50 to 240 m. They are wound into coils. And to connect the entire system to the collector, you will have to buy larger diameter water pipes.
The modern system of warm water floors is identified with a high level of coziness and comfort. This floor effectively heats the room and does not have a harmful effect on the life and health of residents. Such results can only be achieved if the calculations are correctly performed and the installation work is carried out correctly.
A warm water floor can be the main source of heating for a living space or serve as an auxiliary heating element. The main calculations of such floors are based on data from the operating scheme: light heating of the surface to improve comfort or providing full heat to the entire area of the room. The second option requires a more complex design of the heated floor and a reliable adjustment system.
Calculations and design are based on several characteristics of the room, as well as the choice of heating option - main or additional. Important indicators are the type, configuration and area of the room in which the installation of this type of heating system is planned. The optimal option is to use a floor plan indicating all the parameters and dimensions necessary for calculations. You are allowed to take the most accurate measurements yourself.
To determine the amount of heat loss, you will need the following data:
- the type of materials used in the construction process;
- glazing option, including type of profile and glass unit;
- temperature indicators in the region of residence;
- use of additional heating sources;
- exact dimensions of the room area;
- expected temperature in the room;
- floor height.
In addition, the thickness and insulation of the floor, as well as the type of floor covering to be used, are taken into account, which has a direct impact on the efficiency of the entire heating system.
When performing calculations, you should take into account the desired temperature for the room being equipped.
Heated floor pipe consumption depending on the loop pitch
| Pitch, mm | Pipe consumption per 1 m2, m p. |
|---|---|
| 100 | 10 |
| 150 | 6,7 |
| 200 | 5 |
| 250 | 4 |
| 300 | 3,4 |
Design Features
All calculations of water heated floors must be made extremely carefully. Any defects in the design can only be corrected by completely or partially dismantling the screed, which can not only damage the interior decoration of the room, but will also lead to a significant expenditure of time, effort and money.
- living space - 29 °C;
- areas near external walls - 35 °C;
- bathrooms and areas with high humidity - 33 °C;
- under parquet flooring - 27 °C.
Short pipes require the use of a weaker circulation pump, which makes the system economical. A circuit with a diameter of 1.6 cm should not be longer than 100 meters, and for pipes with a diameter of 2 cm the maximum length is 120 meters.
Calculation rules
To install a heating system on an area of 10 square meters, the best option would be:
- use of 16 mm pipes with a length of 65 meters;
- the flow rate of the pump used in the system cannot be less than two liters per minute;
- the contours must be of equal length with a difference of no more than 20%;
- the optimal distance between pipes is 15 centimeters.
It should be taken into account that the difference between the temperature of the surface and the coolant can be about 15 °C.
The optimal method for laying a pipe system is represented by a “snail”. It is this installation option that promotes the most uniform distribution of heat over the entire surface and minimizes hydraulic losses, which is due to smooth turns. When laying pipes in the area of external walls, the optimal step is ten centimeters. To perform high-quality and competent fastening, it is advisable to carry out preliminary markings.
Pipe and power calculations
The data obtained as a result of measurements is the basis for calculating the power of equipment such as a heating heat pump, gas or electric boiler, and also allows you to determine the distance between pipes when performing installation work.
- stainless steel corrugated pipes are characterized by efficiency and high-quality heat transfer;
- copper pipes are characterized by a high level of heat transfer and impressive cost;
- cross-linked polyethylene pipes;
- metal-plastic version of pipes with an ideal ratio of quality and cost;
- foamed propylene pipes with low thermal conductivity and affordable price.
The use of special computer programs can significantly simplify calculations and make them as accurate as possible. All calculations must be carried out taking into account the installation method and the distance between the pipes.
The main indicators characterizing the system are:
- required length of the heating circuit;
- uniform distribution of released thermal energy;
- the value of the permissible limits of active thermal load.
It should be taken into account that if the area of the heated room is large, it is possible to increase the laying step while simultaneously increasing the temperature of the coolant. The possible range of steps when laying is from five to sixty centimeters.
The most common ratios of distances and thermal loads:
- a distance of 15 centimeters corresponds to a coolant of 800 W per 10 m²;
- a distance of 20 centimeters corresponds to a coolant from 500 to 800 W per 10 m²;
- a distance of 30 centimeters corresponds to a coolant of up to 500 W per 10 m².
To know for sure whether it is enough to use the system as the only source of heating or whether “warm floors” can serve solely as an addition to the main heating, it is necessary to perform a rough, preliminary calculation.
Rough calculations of the thermal circuit
To determine the density of the effective heat flux emitted by m² of heated floors, you must use the formula:
g (W/m²) = Q (W) / F (m²)
- g - heat flux density indicator;
- Q is the total indicator of heat loss in the room;
- F - floor area expected for arrangement.
To calculate the Q value, the area of all windows, the average height of ceilings in the room, and the thermal insulation characteristics of floors, walls and roofs are taken into account. When performing underfloor heating as an additional option, it is advisable to determine the total volume of heat loss in the form of a percentage.
When calculating the value of F, only the area of the floor involved in the process of heating the room must be taken into account. In areas where interior items and furniture are located, free zones about 50 centimeters wide should be left.
To determine the average temperature of the coolant under the conditions of the heating circuit, the formula is used:
ΔT (°C) = (TR + TO) / 2
- TR is the temperature indicator at the entrance to the heating circuit;
- TO - temperature indicator at the exit from the heating circuit.
The recommended temperature parameters in °C at the inlet and outlet for a standard coolant are: 55-45, 50-40, 45-35, 40-30. It should be taken into account that the supply temperature cannot be higher than 55 °C, with the condition of the return temperature being a difference of 5 °C.
In accordance with the obtained values of g and ΔT, the diameter and pitch for pipe installation are selected. It is convenient to use a special table.
At the next stage, the approximate length of the pipes involved in the system is calculated. For this purpose, it is necessary to divide the area of the heated floor in m² by the distance between the laid pipes in meters. To the resulting indicator, you should add the length reserve for making bends and the connection length is added to the length for pipe bends and the length for connecting to the collector system.
With a known length and diameter of the pipes, the volume and speed of the coolant can be easily calculated, the optimal value of which is 0.15-1 meter per second. At higher travel speeds, the diameter of the pipes used should be increased.
The correct choice of pump used in the heating circuit is based on the coolant flow rate with a margin of twenty percent. This increase in the indicator corresponds to the parameters of hydraulic resistance in the pipe system. The selection of sediment for the circulation of several heating systems consists in matching the power indicators of this equipment with the total flow rate of all heating circuits used.
To get the most accurate calculations, it is advisable to seek advice from professionals who specialize in installing internal utilities.
It is possible to use an online calculator, which will facilitate the calculations, but will give very rough calculations that provide general information about the scale of the upcoming installation work.
To heat old and dilapidated buildings that do not have high-quality insulation, it is not advisable to use a warm water floor system as the only heating element, which is due to the low degree of efficiency and high energy consumption.
The level of technical literacy of all calculations performed has a direct impact on the quality characteristics of the installed heating system. Correct calculations allow you to optimize financial costs not only for the process of installing water floor heating, but also to minimize costs during operation and maintenance of the entire heating system.
Video - Calculation of water-heated floors (part 1)
Video - Calculation of a water-heated floor (part 2)
One of the conditions for comfortable living in a private house is the presence of a high-quality heating system. To achieve uniform heating of all rooms without exception, owners prefer to install a warm water floor.
The design is easy to install and quite practical to use, which means you can handle its installation yourself. In order for the equipment to work efficiently and to avoid failures and malfunctions, it is necessary to carefully approach the issue of calculating the pipe for a heated floor.
All calculations can be carried out with the help of a specialist or use the recommendations presented below.
How to install a heated floor?
The modern market offers a huge range of floor pipes. They all differ in length, diameter, and shape. In order for all measurements to be as accurate as possible, it is necessary to understand the design of this design.
The most popular installation methods are: floor and concrete. In the first case, the floor is made of polystyrene or other material. Its advantage is its quick installation, since it does not require pouring and further drying.
As for the concrete option, it requires the presence of a screed, which takes a lot of time to apply and dry. In this case, the pipes are installed along the contour. The cost of purchasing pipes directly depends on the material you choose.
How to determine the length of the pipe for a heated floor?
Before installing the structure, you must accurately calculate the number of component materials, including pipes. First, you need to divide the room into equal squares. This is easy to do with graph paper. When drawing a drawing, do not forget to take into account the correct scale.
The number of squares obtained will directly depend not only on the area of the room, but also on its geometry.
When installing a heated floor, the length of one pipe should not exceed 120 m. And there are a number of objective reasons for this:
- The coolant, being in the circuit, during operation can affect the screed and, if installed incorrectly, damage it;
- temperature differences can damage the floor covering (parquet, linoleum, etc.);
- By distributing the surface into several zones, you contribute to the uniform and efficient distribution of heat and, accordingly, the water itself.
Methods for installing pipes for heated water floors
After dividing the space into equal parts, you need to plan how to lay the contour, there are several types of forms:
- snake;
- double snake (use in installation of two pipes);
- snail (laying occurs towards the center using a double bend);
- corner snake (pipes come out from the corner of the room).
Depending on the chosen form of installation, you should calculate the number of pipes for the heated floor.
Laying the floor with a snail is popular in large rooms of a standard shape (in the form of a rectangle or square). This will ensure that heat spreads throughout the room.
For a long small room, the optimal arrangement of the floor will be in the form of a snake.
Calculation of the heating floor installation step
When installing a heating system, you must maintain a certain interval between pipes. This indicator is called the step and the smaller its value, the longer the contour length is needed.
The optimal pitch is considered to be the effective use of the pipe, while residents should not feel the difference between individual sections of the floor in the room.
Closer to the edge the step should correspond to 10 cm, and closer to the center with an approximate difference of 5 cm in the larger direction.
| Pitch, mm | Pipe consumption per 1 m2, m.p. |
|---|---|
| 100 | 10 |
| 150 | 6,7 |
| 200 | 5 |
| 250 | 4 |
| 300 | 3,4 |
The maximum step value should not exceed an interval of 30 cm, because the required level of surface heating will not be provided.
Calculation of pipe length for a warm water floor
There are many ways to calculate the length of a contour, but the simplest is to use the average value, which is 5 m of linear products per 1 m 2 of area.
In this case, the step will be the optimal value - 20 cm. And you can quickly determine the length using the formula:
L=S/N*1.1, Where
L– required pipe length;
S– usable area of the room;
N– pipe laying pitch;
1,1 – sufficient supply of pipes for connections and turns.
In addition, the distance from the collector to the floor must also be added to the obtained value.
Determining the length of the contour for a heated floor
As mentioned above, in addition to the considered values, it is necessary to take into account the diameter of the pipes, as well as the material from which they are made.
If you have chosen a metal-plastic structure, then with a diameter of 16 inches, the total length of the heating circuit should be less than 100 m. The ideal, from the point of view of such a scheme, is a pipe from 75 to 80 m.
Polyethylene products with a diameter of 18 mm should not exceed 120 m, but in fact the value varies from 90 to 100 m.
The best choice for purchase would be metal-plastic structures, which are characterized by high efficiency and durability.