In winter, very low temperatures can be observed. Even if the thermometer drops below 0º, the water in the pipes starts to freeze. If there are open sections of water supply and sewage systems that are not protected from freezing, the functioning of such important life support systems becomes impossible.
To ensure the normal operation of water communications, which are located on the street or in unheated rooms, special electrical wires are used. How pipes are heated will be discussed later.
Application area
Electric heating of the pipe allows maintaining the optimum temperature inside, at which the water does not freeze. Today, various wires are used to create such a system. They can significantly differ in appearance, functionally. Depending on the type of wire, they can wrap pipes or start the heating wire directly inward.
The presented systems are mounted on various pipelines. It can be domestic and industrial communications. Pipes are insulated not only outside buildings, but also inside basements, attics, and other unheated rooms. 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 systems presented are used to ensure the normal functioning of the sewage system, various tanks, drainage, and fire hydrants.
Functions
The heating of the water pipe from freezing is carried out 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 the communications in a liquid state.
Also, the wire prevents the formation of plugs from ice, preventing the absence of movement of contents through the system. Water can move freely through pipes. At the same time, its speed of movement increases. No liquids are formed from liquids that move inside the pipes. No condensation forms on the surface of the pipes.
Owners of a private house may not always be in their country cottage in winter. If they come here periodically, you will need to protect communications from freezing. Otherwise, they will not be able to operate the water supply system, sewer. From low temperatures, ice appears inside the pipes. In some cases, a break in communications is possible. When it gets warmer, water will leak out of the pipes. Therefore, it is important to install the heating cable correctly.
Varieties
For heating pipes, various electrical wire systems are used. They can be divided into two large groups. This is a resistive and self-regulating heating cable.
The 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. He heats the conductor, all the shells of the wire. This is a robust system that can differ in insulation class and power. Depending on the characteristics of the outer sheath, the presented cable can be routed directly into the pipe or wrapped around the communications.
The self-regulating wire consists of two cores, between which there is a polymer matrix of semiconductor material. Electricity flows through the system in a larger volume if the environment gets colder. The heating of the wire will be stronger in this case. When the environment gets warmer, the matrix reduces the supply of electricity through the system. The wire will heat less.
Resistive Wire Features
Heating of plastic pipes and metal communications is possible using a resistive cable system. Such a wire is heated to a certain temperature. In order to be able to adjust the heating level, a temperature regulator must be added to the system.
The resistive wire consists, as already mentioned above, of the core and protective shells. For this, manufacturers use different materials. Depending on the chosen protective sheaths, the cable receives special operational 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 the communications. When using the presented wire, it is important to calculate the required power. Also, the density of laying of turns of wire plays an important role in creating high-quality heating.
Resistive Wire Disadvantages
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 along which the wire is laid must also have an identical temperature along the entire length. If this is not the case, in some areas the cable will overheat. This significantly reduces its service life.
It is also forbidden to cross the wire, which greatly complicates its installation on hydrants, cranes. If you lay the cable turns close to each other, then the system can also overheat.
Another disadvantage is the need to use a temperature controller. This increases the cost of installing pipe heating.
Features of self-regulating wire
Self-regulating tape for heating pipes differs in a number of features. This system does not require a temperature controller. 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, in contrast to the resistive wire. It consists of individual blocks. Therefore, in different parts of the tape the temperature may be different. This does not reduce the life of the wire. If there is an extra piece of tape, you can simply trim it. The resistive cable will have to be laid completely.
Depending on the braid, a self-regulating wire can also be routed directly into the water pipe. In this case, less cable is required. Its efficiency will be higher, since the water inside the system will directly heat. In this case, less energy is consumed.
Cost of wires
The pipe heating system today is carried out using both categories of wires. Despite the fact that the resistive wire has a lot of disadvantages, compared 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 a self-regulating wire is its relatively high cost.
However, it should be noted that the total cost of the resistive wire system with a temperature controller will be from 1800 rubles. per 1 m of cable. The indicated price includes the price of the thermostat. It costs about 800-1500 rubles. Without a control system, the wire cannot be installed.
A self-regulating wire costs about 500 rubles. for 1 m. If you need to purchase a similar system in bulk, the price can be reduced to 250 rubles. for 1 m. In this case, the installation will be much cheaper than when buying a resistive wire.
Benefits of self-regulating wire
A self-regulating heating cable has a lot of advantages when compared with resistive systems. Its main feature is the lack of a temperature regulator. The durability and quality of heating when using a self-regulating wire will be higher.
The system is protected against 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 level of heating of the wire. In this case, under equal conditions, more will be spent.
Self-regulating 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 many wires as necessary for this object. The system is connected to the network using a conventional electric plug.
System power
The water pipe is heated with a cable of a certain power. In order for the system to work efficiently, it is necessary to consider to what point the thermometer column can fall to in winter. Also, when 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 the material, the pipe is made of, as well as the thickness of the insulation above it.
There is a certain formula that experts use to calculate the power of the wire. It looks like this:
M = (2 x 3.14 x Tt x D x (Tl - Tn) / Dk x (Dt / Dn) x 1.3, where:
- Tm is the thermal conductivity of the insulation. For calculations, the most commonly used indicator is 0.04.
- D is the length of the pipe.
- Tj is the temperature of the fluid in the pipe.
- Tn is the minimum temperature outside.
- Dt - the outer diameter of the pipe along with thermal insulation.
- Dn - the outer diameter without insulation.
- Dc - cable length.
To find the indicator Dk, it is necessary to take into account not only the length of the object, but also all the plugs, hydrants and other elements of the system.
Calculation Example
To find the power of the wire needed for heated pipes, you need to make a calculation. To do this, consider a number of system parameters. For example, the owner of a private house has a water pipe, which must be insulated. Its diameter without thermal insulation is 32 mm. The length of the object is 45 m. It is also known that in this area the temperature in winter does not fall below -35 ° C. It is planned to mount a thermal insulation layer 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 watts.
If you calculate the system power for each running meter, you get a 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 specific variety is selected.
If the wire is mounted outside the pipe, the minimum power for a pipe with a diameter of 32 mm is 15 W / m. With increasing cross-sectional size of communications, this indicator 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 the pipe heater , you need to purchase a cable of the required power and length. If you plan to install a resistive variety, a temperature regulator with a remote sensor is purchased without fail. He will control the heating.
It is also mandatory that an RCD is mounted in the system. They are mounted in a special control cabinet mounted inside the house. In addition, an additional aluminum tape for attaching the wire, thermal insulation on the pipe is purchased.
Wire mounting
Before installing a pipe heater, carefully read the manufacturer's instructions. The wire can be mounted on the pipe in a spiral or run in a straight line. The choice depends on the features of the communication. Using 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 a temperature regulator is installed on the pipe surface. It is also fixed with adhesive tape. Next, the system is covered with a layer of thermal insulation.
Having considered the features of the choice and installation of pipe heating, you can correctly install an effective system on the desired object.