Very cold temperatures can occur in winter. Even when the thermometer drops below 0º, the water in the pipes begins to freeze. If there are open sections of water supply, sewerage, which are not protected from freezing, the functioning of such important life support systems becomes impossible.
To ensure the normal operation of water communications that are located on the street or in unheated premises, special electrical wires are used. How pipes are heated will be discussed later.
Scope of application
Electrical heating of the pipe allows you to maintain the optimum temperature inside, at which the water does not freeze. Today, various wires are used to create such a system. They can differ significantly externally, functionally. Depending on the type of wire, it can wrap around pipes or lead the heating wire directly inside.
The presented systems are mounted on various pipelines. It can be household and industrialcommunications. Pipes are insulated not only outside buildings, but also inside basements, attics, and other unheated premises. Regardless of the location of communications, electric cables are used for heating. Pipes can lie in the thickness of the earth or pass on the surface.
In addition to heating the water supply, the presented systems are used to ensure the normal functioning of sewers, various tanks, drainage, and fire hydrants.
Functions
Water pipes are heated from freezing through various types of systems. All of them perform identical functions. The cable, regardless of the type and method of installation, maintains the contents inside communications in a liquid state.
Also, the wire prevents the formation of ice plugs, preventing the contents from moving through the system. Water can move freely through the pipes. At the same time, its speed increases. Liquids that move inside the pipes do not form solid fractions. Condensation does not form on the surface of the pipes.
Not always the owners of a private house can be in their country cottage in winter. If they come here periodically, it will be necessary to protect communications from freezing. Otherwise, they will not be able to operate the water supply and sewerage. From low temperatures, ice appears inside the pipes. In some cases, communications may be interrupted. When it warms up, water will seep out of the pipes. Therefore, it is important to properly install the cable forheating.
Varieties
Different systems of electrical wires are used to heat pipes. They can be divided into two large groups. It is a resistive and self-regulating heating cable.
Resistive wire has a stable temperature, which does not change along the entire length of the wire. This cable consists of a metal core through which current is supplied. It heats the conductor, all the sheaths of the wire. This is a robust system that may differ in insulation class and power. Depending on the characteristics of the outer sheath, the presented cable can be led directly into the pipe or wrapped around communications.
Self-regulating wire consists of two cores, between which there is a polymer matrix of semiconductor material. Electricity travels through the system to a greater extent if the environment gets colder. The heating of the wire will be stronger in this case. When the environment warms up, the matrix reduces the supply of electricity through the system. The wire will heat up less.
Features of resistive wire
Heating of plastic pipes and metal communications is possible when using a resistive cable system. Such a wire is heated to a certain temperature. To be able to regulate the level of heating, a thermostat must be added to the system.
A resistive wire consists, as mentioned above, of a core and protective sheaths. For this, manufacturersuse different materials. Depending on the selected protective sheaths, the cable receives special performance characteristics. If the outer layer is additionally reinforced and made of food-grade plastic, the wire can be installed directly into the water pipe.
However, more often the wire is pulled from the outside of communications. When using the presented wire, it is important to calculate the required power. Also, the density of laying the turns of the wire plays an important role in creating high-quality heating.
Disadvantages of resistive wire
Today, many manufacturers produce a cable for heating pipes, which has a lot of characteristics. However, there are certain disadvantages that are inherent in almost all resistive wires.
The presented category of heating systems, as mentioned above, is characterized by the same temperature along the entire length. This means that the system through which the wire is laid must also be at the same temperature along its entire length. If this is not the case, in some areas the cable will overheat. This greatly shortens its service life.
It is also forbidden to cross the wire, which greatly complicates its installation on hydrants, taps. If you lay the turns of the cable close to each other, then the system may also overheat.
Also, the disadvantage is the need to use a thermostat. This increases the cost of installing heating pipes.
Features of self-regulating wire
Self-adjustingpipe heating tape has a number of features. This system does not require a thermostat. The built-in matrix itself determines to what temperature the wire needs to be heated at the moment.
Moreover, it should be noted that the self-regulating cable can be cut, unlike the resistive wire. It consists of separate blocks. Therefore, in different parts of the tape, the temperature may not be the same. This does not reduce the life of the wire. If there is an extra piece of tape left, you can simply cut it off. The resistive cable will have to be laid completely.
Depending on the braid, the self-regulating wire can also be led directly into the water pipe. In this case, less cable is required. Its efficiency will be higher, since the water inside the system will be heated directly. In this case, less electricity is used.
Cost of wires
The pipe heating system today is performed using both categories of wires. Despite the fact that the resistive wire has a lot of disadvantages, in comparison with self-regulating varieties, it is installed on various communications of private and industrial facilities. This is due to the lower cost of such a system. The disadvantage of self-regulating wire is its relatively high cost.
However, it should be noted that the total cost of a resistive wire system with a thermostat will be from 1800 rubles. for 1 m of cable. At the indicated pricethermostat included. It costs about 800-1500 rubles. It will not be possible to install the wire without a control system.
Self-regulating wire costs about 500 rubles. per 1 m. If you need to purchase such a system in bulk, the price can be reduced to 250 rubles. for 1 m. In this case, installation will be much cheaper than when buying a resistive wire.
Advantages of self-regulating wire
Self-regulating heating cable has many advantages when compared to resistive systems. Its main feature is the absence of a thermostat. The durability and quality of heating will be better when using a self-regulating wire.
The system is protected from overheating. It adapts to environmental conditions. In this case, the cable consumes the optimal amount of electricity. Owners of a resistive heating system must independently set the heating level of the wire. In this case, more electricity will be spent under equal conditions.
Self-adjusting wire is easy to install. It can be crossed, providing heating for hydrants and taps. If necessary, the system is cut into sections up to 15 cm long. This allows you to mount exactly as much wire as necessary for a given object. The system is connected to the network using a conventional electrical plug.
System power
The water pipe is heated by a cable of a certain power. In order for the system to work effectively, it is necessary to take into account how high the thermometer can drop in winter. Alsowhen choosing the power of the system, it is important to pay attention to the location of the object, its length. The diameter of the pipe affects the choice of wire power. When calculating, be sure to take into account the material from which the pipe is made, as well as the thickness of the insulation above it.
There is a certain formula that experts use to calculate wire power. She looks like this:
M=(2 x 3, 14 x Tt x D x (Tzh - Tn) / Dk x (Dt / Dn) x 1, 3, where:
- Тт - thermal conductivity of insulation. For calculations, the most commonly used indicator is 0.04.
- D - pipe length.
- Tf is the temperature of the liquid in the pipe.
- Tn - minimum outside temperature.
- Dt - the outer diameter of the pipe together with thermal insulation.
- Dn - outer diameter without thermal insulation.
- Dk - cable length.
To find the Dk indicator, it is necessary to take into account not only the length of the object, but also all plugs, hydrants and other elements of the system.
Calculation example
To find the wire power required for heated pipes, you need to make a calculation. For this, a number of system parameters should be taken into account. For example, the owner of a private house has a water pipe that needs to be insulated. Its diameter without thermal insulation is 32 mm. The length of the object is 45 m. At the same time, it is known that in this area the temperature in winter does not fall below -35ºС. It is planned to mount a layer of thermal insulation on the pipe, which will be 25 mm.
To select the optimal system, you need to calculate according to the above formula. It will look like this:
M=3.14 x 2 x 45 x 0.04 x (5 - (-35)) / 73 (82/32) x 1, 3.
M=625 W.
If you calculate the power of the system per linear meter, you get the result of 14 W/m.
Various wires are on sale. Their power varies from 10 to 40 W/m. Depending on the operating conditions, a certain variety is chosen.
If the wire is mounted outside the pipe, the minimum output for a 32 mm pipe is 15 W/m. With an increase in the size of the cross section of communications, this figure increases. If the pipe has a diameter of 50 mm, the recommended power reaches 24 W / m, and for 150 mm - 40 W / m.
If the wire is installed inside the pipe, low-power systems can be used. For communications with a cross section of up to 80 mm, wires with an indicator of up to 13 W / m are suitable.
Mounting Features
To mount pipe heating, you need to purchase a cable of the required power and length. If you plan to install a resistive variety, a thermostat with a remote sensor is purchased without fail. It will control the heating.
Also, an RCD must be installed in the system. They are mounted in a special control cabinet mounted inside the house. An additional aluminum adhesive tape for attaching the wire, thermal insulation on the pipe is also purchased.
Installation wire
Before installing pipe heating, you should carefully read the manufacturer's instructions. The wire can be mounted on a pipe in a spiral or run in a straight line. The choice depends oncommunication features. Using adhesive tape, the cable is fixed to the surface. If you plan to install the wire inside the pipe, you will need to turn off the water supply. At the appropriate point, the cable is inserted into the system.
If necessary, a sensor from the thermostat is installed on the surface of the pipe. It is also fixed with tape. Next, the system is covered with a layer of thermal insulation.
Having considered the features of the selection and installation of pipe heating, you can correctly install an effective system on the required object.
