In winter, water supply interruptions often occur in private homes due to freezing pipes. Even if the water supply lines are installed below the freezing point, there are still weak areas in them, which include the place of entry into the house. The problem can be solved by using a heating cable for heating pipes. In this case, communications can be laid close to the surface, and more powerful heating can be organized near the place of entry into the house.
Content
- Types of cables
-
Installation methods
- Installation inside pipes
- External mount
- Insulation materials
- Required power
- The presence of a thermostat
Types of cables
The modern market offers two types of pipe heating cables: resistive and self-regulating. The work of the first is based on the property of conductors to heat up when current passes. A metal wire is used as a heating element. The cable temperature is constant and does not depend on how cold it is outside. It will provide maximum heating and consume the same amount of energy both at -2 ºC and at -30 ºC. To save energy during warming, temperature sensors and heat regulators, similar to those used in underfloor heating, are installed on resistive devices.
Another feature of resistive heating elements is that during installation, they should not be allowed to intersect or be located close to each other. This threatens overheating and system breakdown. You need to carefully monitor this during installation.
The manufacturer produces two types of resistive wires: single-core and two-core. The latter are used much more often. This is due to the fact that the former have both ends connected to the electrical network, which is not very convenient. The two-core cable is equipped with a plug on one side, and an electrical cord with a plug for connecting to an outlet on the other. Resistive elements must not be cut. They are laid completely, even if the length of the wires is much longer than necessary.
Self-regulating heating cables for water supply, unlike resistive ones, are able to change the amount of heat generated depending on the ambient temperature. Electrical conductors in them are intended only for conducting current, and heating is performed using a polymer material.
This polymer has a special property: when heated, it emits less heat, and when it cools, more, so the cable was called self-regulating. Such devices have the following advantages:
- Intersections and contact of wires do not affect their operation and do not lead to burnout.
- They can be cut to the desired length, for which the surface of the devices is marked. An end sleeve must be installed on the cut end.
The water supply system must be insulated even with any kind of heating cable installed. Otherwise, too much heat will be required to heat it. In severe frosts, the cable may not cope with heating, and the water supply system will freeze.
Installation methods
Self-regulating cable for heating pipes can be installed both outside and inside the water supply system. Each type of installation has its own types of wires. Some models are for outdoor use only, others for indoor use. The installation method is indicated in the product specifications.
Installation inside pipes
Devices intended for indoor installation must meet certain criteria. The requirements for this type of installation are as follows:
- the coating does not emit toxic substances;
- the devices have a degree of electrical protection not lower than IP68;
- the end sleeve is completely sealed.
For the installation of a self-regulating heating cable for heating pipes, a tee is installed at the end of the water supply. A wire is tucked into one of its branches inside the pipe through the gland. The connector, installed where the electric wire goes into the heating element, must not go into the pipe and the gland, as it is not designed for humid environments. The angle of the outlet of the tee does not matter, since the cable is not fixed, but simply wound inward.
External mount
Before installing the heating wire, the pipes are cleaned of dust, dirt and rust. Laying is done on a clean surface. Anything that could damage the device must be removed. The wire is laid along the pipes. It is fixed every 30 cm. Fixation is carried out with metallized adhesive tape or plastic clamps. The cable should be positioned so that it adjoins the entire area of the pipe.
If no more than two wires are used for heating, then they are laid along the bottom of the pipes in the coldest place. They are carried out in parallel and at a short distance from each other. If 3 or more wires are installed, then they are positioned so that most of them remain at the bottom. A gap is strictly maintained between them, which is especially important for resistive devices.
The wire can be installed in another way, laying the turns in a spiral. This is done by gradually unwinding the bay. Avoid sharp bends in the cable. You can also fix the slack wire first, and then wind and fix it with metallized tape.
If a self-regulating heating cable is mounted on a plastic pipe, then adhesive tape is placed under the wire, which will improve thermal conductivity. On tees, valves and other connecting devices, several loops of wire are made to help protect them from freezing. In this case, you need to ensure that the cable does not bend too much.
Insulation materials
Mineral wool should not be used for insulation, since it loses its insulating qualities when it gets wet. If wet cotton wool freezes, then after thawing, it crumbles into dust. Since the environment around the water supply system is usually humid, such insulation cannot be used.
Materials that crumple under the influence of gravity must be handled with care. When compressed, they lose their insulating properties. Heaters such as foam rubber can be used only if the water supply is laid into a specially equipped sewer system. But if the pipe is simply installed underground, then rigid materials must be used for insulation. Another option is to put a plastic sewer pipe on top of a soft insulation, for example, foamed polyethylene.
A good type of insulation is expanded polystyrene, which is released in the form of pipe fragments. It is sometimes called a shell. This material tolerates loads well, has good thermal insulation properties and moisture resistance.
Required power
This parameter should be given special attention, since it depends on many factors. These include:
- region of residence;
- pipe diameter;
- heating cable laying method (indoor or outdoor);
- type of insulation.
Usually, each manufacturer provides a table for their products, which indicates how much cable is consumed per 1 m of pipe.
When using a medium insulation (expanded polystyrene, 30 cm thick), a 10 W / m cable is required for internal insulation of 1 m of water supply. If the pipe is insulated from the outside, then the heating power should be 17 W / m. These figures are applicable for central Russia, but the farther north the region of residence is, the thicker the insulation and more powerful heating should be.
The presence of a thermostat
To minimize the cost of heating pipes, you need to install a thermostat. It is required even if a self-regulating cable is installed. Typically, heating automatically turns on when the water temperature drops to +3 ºС, and turns off at +13 ºС.
But if water is taken from a well, then its temperature will never rise to such a value, so the cable will heat it even in the warm season. During the summer months, the heating wire can be turned off, but in early spring and late autumn it is dangerous to do so due to the possibility of frost. Also, there is no need to heat the water entering the cistern.
This problem is solved by the thermostat, on which the shutdown temperature is set to +5 ºС. Its use can significantly reduce heating costs and increase the useful life of a cable with a fixed resource of working hours.
Simultaneously with the thermostat, a temperature sensor must be installed. It is mounted on a pipe. So that the indicators are not affected by heating, the sensor must be isolated from the heater.
The thermostat must be installed indoors. A heating cable and a temperature sensor are connected to it. The connection should be made in accordance with the marking on the device. It is better not to buy a device without marking, since its quality is questionable.
Self-regulating heating cable protects the water supply from freezing. It automatically regulates the generated heat, heats the pipes less when it gets warmer, and more when it gets colder. To prevent the wire from warming into the water in the warm season, a thermostat with a temperature sensor is installed.
