Installing Underfloor Heating Pipes: The Step Of Laying, Proper Fixing, Installation Secrets

The layout and pitch of the pipes determines the performance of the water underfloor heating. That is why it is not enough just to buy components for the system, it is also necessary to calculate the heat output, to choose the optimal arrangement of rings or pipe coils.

Order, no one is attracted by the prospect of investing money and not getting the planned effect. All about the design of underfloor heating and schemes, according to which the laying of underfloor heating pipes, you will learn from the article presented by us.

Following the proven and systematized by us information will help to arrange a perfectly working underfloor heating. The basis for the information we offer is the requirements of the building regulation manuals.

We have set out in detail the principle of the operation of underfloor heating circuits, we have described the device variants and the technology for their implementation. Informative photo and video tutorials clearly confirm the data presented and make the process easier to understand.

Article contents:

  • Water floor heating system
  • Role of manifold knot
  • Collector connection diagram
  • Pipe metreage calculation rules
  • Nouches for optimum pitch
  • Pipe laying diagrams
  • Main methods of pipe installation
    • #1: Installation on profile thermal insulation boards
    • #2: Installation over modular and slatted panels
    • #3: Installing piping over screed
  • Conclusions and helpful videos on the subject

Water underfloor heating system

The distinguishing feature of underfloor heating is that it has no external heating structures, but the system itself stores and radiates the heat received.

When heat is properly distributed over the surface of the flooring, it is possible to save 30% or more on heating medium consumption.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

Floor heating system can be represented by one of the varieties: water, electric, film, rod or electric-water. The latter is considered a novelty, but due to its wide range of advantages, it has already won many fans

For efficient use of the floor heating system, let us consider additional ways to help save money:

  1. The liquid circuit length does not exceed 70 m.When choosing the optimal pipe laying pitch, the heat carrier transport is almost lossless.
  2.  Mixing hot and cold streams.  The use of return water makes it possible to use less boiler energy.
  3. Detailing of the circuit layout with a precise pitch calculation. Prearranging the furniture positions will save on consumables and consequently on the circuit itself.
  4.  When the system is at maximum heat, reduce the temperature by 20°C.This action will save 13% of the heating medium.

For the best result, the installation technique must be strictly followed. The heating mechanism of such a system consists of several layers, each having a specific function.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

The heating system with underfloor heating is constructed in phases. Work on each of them will take some time, e.g. after the pouring, the subsequent works can be started only in 2-4 weeks

Heating the room with liquid floor heating is organised in several steps:

  1. Damp-proofing. This layer eliminates products resulting from condensation. Even polyethylene film can be used for the substrate.
  2. Therm insulation. The main task is to eliminate heat leakage to the bottom. In most cases sheet type insulation is used. The thickness should be selected based on the conditions of the room - whether the house has a basement or ground floor. The colder the climatic conditions, the thicker the insulation.
  3. Foil or heat reflective element. A foil that helps to redirect the heat flow upwards as much as possible. The laying of this material saves up to 5% on heat flow.
  4. Pipe installation. The basic device of the whole mechanism. The heated fluid flows through the pipes. If you choose the right pitch between the coils of pipes when laying the underfloor heating, this gives the possibility of efficient heating with the least expenditure of heat resources.
  5. Stretch. Provided all previous layers have been laid on a flat surface, the thickness of the screed will be minimum - 3.5 cm. Often a 50 mm thickness of ordinary cement-sand mixture is used. The heat conductivity of such material is 0.4 W/(m*K).
  6. Floor covering. A liquid floor allows the installation of any material. However, the best characteristics, namely thermal conductivity and maximum return, are ceramic tiles.

The installation technology requires the initial arrangement of a collector unit. Only after that can the individual layers of the system be laid.

The role of the manifold node

Not everyone knows that underfloor heating with a water circuit can also function properly without a manifold. But even less know what it looks like in practice.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

The manufacturers recommend using pipes no longer than 70 m long. If the coils are positioned with a maximum pitch gap, this length is only long enough for 7 m2, which ensures making three loops in a room with an average area

But the floor heating system is in most cases installed for several rooms. In this case it is not possible to ensure a uniform distribution of the heating medium without a manifold.

Floor heating installation without a manifold has a number of disadvantages: the heating medium can only be supplied with the same temperature as in the general heating system, automatic air output is not possible, the same applies to the pressure regulation.

Collector connection diagram

The choice of a finished mechanical or automatic model depends on the heating system features.

The first type is recommended for underfloor heating without a radiator, the second can be used in all other cases.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

The Valtec manifold groups are the most popular. The manufacturer provides a 7-year warranty on its products. The assembly diagram of the fluid circuit manifold is already included in the finished manifold

According to the diagram, the assembly of the floor heating manifold is done as follows:

  1. Frame mounting.The prepared wall niche or manifold cabinet can be selected as the mounting area for the manifold. It is also possible to mount directly on the wall. However, the location must be strictly horizontal.
  2. Connection to the boiler.The supply pipe is placed at the bottom, the return pipe at the top. The ball valves must be installed in front of the frame. They will be followed by the pumping group.
  3. Installation of the flow valve with temperature limiter. This is followed by the installation of the manifold.
  4. Hydraulic test of the system. Test by connection to the pump, which helps pressurise the heating system.

In the mixing unit one of the mandatory elements is the two or three way valve. This device mixes water streams of different temperatures and redistributes their flow path.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

In both pipes, return and supply, connected to the manifold unit, shut-off valves and fittings are fitted, designed for balancing the volume of the heat carrier as well as for blocking either of the circuits

If servo drives are used to control the manifold thermostats, then the mixing unit is extended with bypass and diverter valves.

Pipe layout rules

Calculate the metreage of the elements for the underfloor heating installation after drawing up the layout of the complete system.

The calculation takes into account the following nuances:

  1. Pipes are not laid where furniture, oversized floor equipment, household appliances are located.
  2. The length of circuits with different sectional dimensions must meet the following parameters: at 16 mm must not exceed 70 m, 20 mm - no more than 120 m. The location of each circuit corresponds to an area of 15 m2. If you do not adhere to such recommendations in the heating network pressure will be low.
  3. Distance between the length of the lines not more than 15 m. Several heating lines are made for a voluminous room.
  4. If effective thermal insulation materials are used, the optimum pipe spacing is 15 cm. But if the house is situated in a zone with severe climatic conditions, where temperatures fall below -15°C, the distance must be reduced to 10cm.
  5. If a spacing of 15cm was chosen, the material costs are 6.7m per 1m2. Laying pipes with 10 cm spacing is 10 metres per metre2.

The floor heating can only be supplied in one piece. Depending on the meterage, several or one coil of pipes for the water circuit is purchased. It is then divided into the required number of lines.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

When laying the pipes, the hydraulic losses, which increase with each successive turn, must be taken into account. Loops exceeding 70 m are not considered to be used

Water underfloor heating work always starts on the coldest side of the room. The question of choosing the optimal route for the heat carrier is very important - the water temperature decreases closer to the end of the circuit.

Nuances for choosing the optimal pitch

The correct choice of the pitch between the underfloor heating pipes depends on the efficiency and cost effectiveness of the whole circuit.

But its calculation depends on many factors. The standard spacing between loops is 100-200 mm.

Also variable or constant spacing is possible:

  1. If the heating load is less than 50 W per 1 m2the loop spacing will be constant and equal to 200 mm.
  2. In higher heating loads of 80 W per 1 m2 and more the distance will be 150 mm.
  3. In other cases a variable spacing is required. For example, along the perimeter of one or two outer walls, laying the water circuit will be the smallest spacing of 100 mm. Moving towards the center of the room, the gaps will gradually increase to 200 mm.

In practice, if the floor heating is to be heated economically, a pitch of 150 mm is used. This is the optimum value for almost all conditions.

If the heat loss of the building exceeds the heat output, it is worth considering effective insulation - in this case a smaller pitch will not solve the problem.

A detailed algorithm for the calculation of floor heating pipes is described in this article.

Schemes for laying a water circuit

The laying of pipes for a liquid circuit can be made in one of the following ways:

  • coil;
  • double coil;
  • coil.

coil. The method of laying this circuit is the simplest and is done in loops. This option would be optimal for a room divided into different zones, for which it would be convenient to apply different temperature regimes.

The first loop is installed around the perimeter of the room, then the single loop is let inside. Thus, in one half of the room the maximally heated heating medium will circulate, in the other half the cooled one, correspondingly the temperature will be different.

The coil coils may be placed evenly, but the bends of the water circuits will then have strong creases.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

The coil method of pipe placement is ideal for rooms with little heat loss. They are used not only for apartments and private houses but also for industrial facilities where there is a need for heating all year round

Double coil. In this case the supply and return circuits are located near each other throughout the room.

Corner coil. It is used exclusively for corner rooms with two outside walls.

The advantages of the serpentine form include uncomplicated layout and installation. The disadvantages are: differences in temperature conditions in the same room, the bends of the pipes are rather sharp, therefore a small pitch cannot be applied - this may cause a pipe break.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

When laying the circuit in the edge areas of the room (the floor area where the external walls, windows, doors are) the pitch must be smaller compared to the other turns - 100-150 mm

Slipper. Applying this arrangement, the supply and return pipes are mounted throughout the room. They are placed parallel to each other and are installed starting from the perimeter of the walls and moving towards the center of the room.

The supply line in the middle of the room ends in a loop. The return line is then installed parallel to it, which runs from the center of the room and along the perimeter of the room, moving towards the collector.

If the room has an external wall, the pipes may be laid twice along it.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

Under the snail shaped laying, the temperature variations between flow and return may be up to 10°C

The advantages of this method are: uniform heating of the room, low hydraulic resistance due to gradual bends and consumable savings up to 15% compared to the serpentine method. However, there are also disadvantages - complicated design and installation.

Main methods of pipe installation

There are only two methods of laying pipes for underfloor heating - flooring and concrete. In the first method, ready-made materials are used for the base: insulation-polystyrene and panels of modular or slatted type. Here there is no wet work requiring a long drying time, so the installation is fast.

When using the second option, the heating network is bricked up with screed. Depending on the thickness of the concrete, time is calculated for its complete drying. It takes 28 days to harden and only then can the chosen floor covering be installed. This is the most time-consuming and costly method.

#1: Laying on profile thermal insulation boards

The installation of a warm floor system using this method is the easiest. Mats of polystyrene insulation are used as a base here.

The standard parameters of such boards are 30*100*3cm. They have grooves and low posts on which the finishing material is laid.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

Polystyrene mats are not hygroscopic, so they do not lose their original characteristics when exposed to moisture. Even though this material is a polymer, it contains no components that are harmful to health

In this case a concrete screed is not necessary. If tiles or linoleum will be used for flooring, gypsum-fiber boards will initially be laid on the substrate. The thickness of such boards must be at least 2 cm.

#2: Installation on modular and slatted panels

In most cases, such panels are used in houses built of wood. The floor heating pipes are fixed on a raft.

The modular system is fitted with chipboard panels 2.2 cm thick, on which the heating lines are placed. These modules are equipped with channels to accommodate aluminium fixing plates. With this method of laying the layer of insulation will be placed in the wooden floor.

All strips are placed with a distance of 2 cm. Depending on the applicable pitch between the pipes, strips of appropriate length (15-30 cm) and width (13-28 cm) are exploited.

To reduce heat loss, pipe clips are installed on the plates. If linoleum has been chosen for the floor finish, one layer of plasterboard is placed on the pipes, if laminate or hardwood flooring is chosen, this is omitted.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

Laying of modular floor is done with finished elements, which are chipboard panels. They are fitted with grooves to fix the heat carrier pipes

The slatted flooring system is almost identical to the modular flooring system, but uses slats rather than panels, with a minimum width of 2.8 cm.

It is laid directly on the joists at 40-60 cm, with a minimum distance of 2 cm between slats. For thermal insulation choose extruded polystyrene foam or mineral wool.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

Laying the heat lines is done by placing tubes in intermediate holes between the particle boards on slotted aluminium plates

Any method more suitable for wooden floors. In other cases, the more complicated option with a concrete screed is chosen.

#3: Screed Pipe Installation

Despite the laborious process, installation of a heating network with a concrete screed is the most demanded.

The process consists of the following steps:

  1. First, the base is prepared. The unevenness of the subfloor is removed with a hole punch.
  2. The first layer is the waterproofing material. It is laid in strips so that the edges overlap by 20-30 cm. Also the foil should go to the base of the walls by 15 cm. The joints are sealed with construction adhesive tape.
  3. The thermal insulation is laid on top of it.
  4. Damping tape is glued between the future casting and the walls. This action is required to compensate for the expansion of the screed as the floor heats up.
  5. Laying of the reinforcing mesh. It helps to increase the strength of the screed.
  6. Tubes are attached to the reinforcement according to the chosen scheme with the help of plastic tighteners.
  7. Check the floor heating system by filling it with liquid and pressure testing.
  8. Further on, guide beams are installed.
  9. The final step is to pour a cement screed.

For rooms with a large area, a sector division method should be used, with cells not exceeding 30 m2. An individual circuit must be made for each of these.

Installing underfloor heating pipes: the step of laying, proper fixing, installation secrets

If the ground floor is heated, then 20-50 mm thick polystyrene foam is used as insulation. When there is an unheated ground floor or basement below, the thickness of thermal insulation should be 50-100 mmFilling the warm floors with concrete and sand mixture can be done with or without reinforcing mesh.

If the insulation is styrofoam boards with connectors for contours, the use of mesh is not necessary.

When standard thermal insulation material will be used, a thin polymer or metal mesh is used to secure the heat transfer line.

We have a series of articles on the design, installation and connection of water underfloor heating.

We advise you to read:

  1. How to make water underfloor heating with your own hands: a step-by-step guide from design to assembly
  2. Water underfloor heating: options and installation guide

Conclusions and useful videos on the topic

How not to make a mistake in calculating the optimal step for a low-cost circuit arrangement:

How to install a floor heating circuit, the main methods, their disadvantages and advantages:

Challenges you may encounter when choosing pipes for a warm water floor:

The service life of a water heating circuit is about 50 years. However, such high figures are possible only if you follow all the rules when laying them.

Don't forget that the right choice of the optimal pitch will help to save significantly on the purchase of materials, as well as reduce heating costs during operation.

Share with readers your experience of laying a water underfloor heating circuit. Tell us what installation method and scheme you used. Please leave comments on the article and ask questions. The feedback form is below.


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