Heating of the water supply system

The topic to be considered in this publication will be of more interest to the owners of country houses or owners of private houses, especially if building is equipped with a fully autonomous water supply system. Extremely unpleasant is the situation when a sharp cooling in the street is marked more and so, that from the open taps ceases to flow water. There is nothing to be surprised - if it is not foreseen reliable thermal insulation and heating of the water pipe in one of its sections there was a freezing, which ended either with a stopper or such a significant narrowing of the tube lumen that the movement of the water becomes extremely difficult.

This is not only very uncomfortable from a domestic point of view - the consequences can be much worse. If the freezing process is not prevented or stopped, then with a high degree of probability this can lead to the deformation of the pipeline and even to the rupture of the pipe body. All this ends in a major accident with the inevitable overhaul of the water supply system.

Of course, always still in the design of the future house and its engineering networks steps are undertaken to prevent such a situation. Pipes of water pipe are buried in the ground below the freezing level calculated for a specific locality, the reliable of their thermal insulation becomes a prerequisite. However, in some cases, such measures are simply not enough.

. A typical example is that a rocky ridge or some of the reinforced concrete structures located below is simply obstructing the trench. Vulnerable sites are always water withdrawal sites - outlets of their wells or wells, places of the tie into the city water supply network. Often, ice jams occur on the sections of lifting pipes to the building, in unheated basements, in places passing through the concrete massif of the cap and , etc. .

Similar plumbing areas require special attention, and it will be better if electric heating is provided in these places. To accomplish this is not so difficult, because that modern technologies allow using special heating cable for such purposes.

How does the water supply heating

The heating principle is based on the conversion of electrical energy into thermal energy when passing current through special heating cables( similar to the usual operation for all spiral or TES ).The cable is attached from the outside or placed inside the pipe on the most vulnerable areas for freezing. The amount of heat generated by it is sufficient to maintain in the cavity of the pipeline such a minimum possible temperature level, which should rule out the onset of crystallization of water and the transition of its to solid state.

It is quite clear that the cable itself should have reliable electrical and waterproofing with a good margin of safety, so that the would completely be excluded , the probability of rupture, melting, breakdown of the voltage on the pipeline.

Currently, the customer can choose one of several heating cable options:

Resistance heating cables

This type of cable is the simplest in its design. The conductor is made of of a certain alloy with high resistance, and when the electric current passes through it, heat is released.

They are issued in single-core or two-wire variant. Single-core is used infrequently in the circumstances under consideration, for the simple reason that they require a " loopback " circuit, that is, both ends of the cable must converge in one place - at the power source. When heating pipes, this is not always easy to perform, butoften - and in general is impossible.

Two-wire in this regard is more practical - from one end of the cable is connected to the mains, and from the other is installed a contact clutch, ensuring the continuity of the circuit.

The role of the heat source can be performed by one conductor - the second in this case serves only for providing conductivity. In some cables, both wires have heating powers - the power of such devices is , which is much higher.

Conductors are protected by reliable , most often - multi-layered insulation, grounding circuit - screen. The outer layer is a high-strength, resistant to external influences polyvinyl chloride shell.

The positive qualities of these cables include:

• High power and total heat output, which is especially important in large diameter water pipes or with a large number of shaped elements requiring heating( tees, flanges, cranes and . )
• The relative simplicity of the design, which predetermines the and their availability in terms of cost. So, such a cable of minimum power can be purchased at a price of 150 rubles per square meter.

There are some disadvantages for resistive cables:

• . For the economical operation of such a water heating system, it is necessary to purchase and install additional devices - temperature sensors, control units and automatic controls that will maintain the temperature at a given level, including the power supply as needed.
• The cable is implemented by the with a specific footprint, and the end contact bushing must be installed in the production environment. Do not cut the cable by yourself.

Semi-conductor self-regulating heating cables

This type of cable was designed specifically for economy of operation, and is fundamentally different in both device and principle of its operation.

The two metal conductors are separated by a special semiconductor matrix, which acts as a heat radiator. The special properties of the used semiconductor ensure its maximum conductivity at low temperatures, and when they increase the power consumption is significantly reduced. It is characteristic that such a process of self-regulation occurs at each particular point along the entire length of the cable. The temperature along the length of the pipe can is quite different, and, thus, the maximum heating is carried out on the most vulnerable sections of the pipeline.

The advantages of using such a cable are obvious:

• There is considerable saving in terms of electricity consumption. With an increase in the overall air temperature, the system immediately reacts by reducing the power consumption.
• Such a cable can be purchased of any length - on most of its variants is provided for cut in increments of 200 or 500 mm.

The main disadvantage of such a system of water supply heating is a rather high price. So, even the most inexpensive species can cost about 300 rubles per meter, and the upper limit of the cost "rolls over" even for 1000.

The water heating system can mean the external installation of the cable or its placement in the cavity of the pipe. Each of these technologies has its own characteristics,which is taken into account when selecting the right model and when carrying out the work.

Heating cables can be produced with a circular cross-section, but for an external placement on the pipe, a flattened( ribbon) shape is better suited, which will be more in contact with the surface and more efficiently deliver heat energy. The power range is also quite wide - from 10 to 60 W per meter - this should be taken into account when designing a heating system, with taking into account the pipe material and the specific conditions for the location of the water pipe.

There is a rather complicated system for calculating the of the required capacity, which is used by specialists at the stage of drafting. However, is simplified .In domestic conditions, you can focus on the following parameters:

If it is planned to heat the pipeline with the cable placed inside, then a specific power of 10 W / m will suffice for this.

With external cable placement on metal or polymer water pipes, the following indicators are based:

- Ø1 ÷ 2inch-17 W / m;

- ؾ ÷ 1½inch-27 W / m.

More powerful heating cables or tapes( eg 31 W / m) are used in private construction to heat sewer pipes with a diameter of 100 mm and above.

The heating water supply system usually includes the heating cable itself and the "cold" part - the wire for switching with the power source. The "cold cable" can already be connected with the heating part, but more often this work of the has to be done independently. In this case, the bundle may include tubular terminal adapters and the necessary number of heat shrink tubes of different diameters. In the case of using a self-regulating cable, in addition, there must be a special end sleeve, the reliably is an insulating cut-off end.

Video : one of the heating cable assemblies for the

water supply The thermo sensor with the automation unit( thermoregulation) in the kit does not act on the separately. Thermoregulation units are available in different designs - they can be similar to the thermostats of the warm floor with mounting on the wall, installed in the electrical panel on a DIN rail by the type of a conventional machine, fastened directly to the pipe in a convenient for maintenance and controlplace.

For self-regulating cables, compact temperature controllers are available that are placed on the "cold" part of the cable, pre-configured to turn on the power when the temperature falls to 5 ° C and turn off when reaching 15 ° C.

thermoregulator installed. The installation of the water pipe heating system will require the installation of a separate automatic device, with the rated power of 25 amps .Never become unnecessary and the system of emergency protection device - RCD .

Installation of the water heating system

Before the installation is mandatory, the is still inspected the integrity of the cable insulation over its entire length. Neither the does not allow the cable to be laid with signs of surface damage.

One of the most important operations of the - is the switching of the heating part of the cable to a "cold" one, if it was not provided by the manufacturer. Each of the models may have its own specific connection features, which must be reflected in the instructions accompanying the kit. The main task is to ensure a reliable electrical contact and, , together with , to create a multi-layer insulation protection, completely excluding the possibility of a short circuit and breakdown of the voltage to the outside.

An example of cable trimming and its connection to power wire is in the video attached below.

Video: how to properly switch the heating self-regulating cable

When viewing the video, be sure to pay attention to the correctness and reliability of the installation of the end clutch.

Mounting the cable over the water pipe

• The usual cable location is along the pipe in a single line. It is never placed from the top of the pipe. This is done by on for two reasons. First, the probability of its damage should be avoided if there is a possible mechanical load on the pipeline from above( falling objects, of and tools, .) Secondly, freezing of the liquid always goes from below, and this section needs the maximumheating.

• pipe If one cable is not enough for the for the required heating power, start up several "threads" by positioning them as shown in the diagrams:

• pipe Otherwise, lay one cable with a spiralaround the pipe. This can also be performed by the in different ways. :

-Simply wrapping the pipe with a cable with defined by the step;

- This is not always convenient, and in some cases it is simply impossible, the code space for work is limited, and there is no way to pass under the pipe the entire cable bay. Then they act differently: leave the loop loops with their subsequent wrapping around the pipe body in the opposite direction.

• How to fix the cable to the pipe surface? If polymer pipes are used for water supply, then without options - only aluminum tape, which will ensure maximum heat transfer from the cable to the pipe. In this case, the cable is fixed along its entire length.

At the same time, it is possible to increase the heat transfer at the particularly problematic areas by gluing the contact area with an aluminum adhesive tape or even completely wrapping the pipe with foil as far back as the before laying the cable.

• When installing the heating system on a metal pipeline, the cable is fixed in an annular manner with the defined by the between the fastening points( no more than 300 mm).Use at the same time recommend a heat-resistant adhesive tape or a special plastic cable bandage.

There are cable laying features on some parts of the water pipe:

• When placing the cable in a corner, it should be as close to the outside radius as possible.

• pipe A lot of heat is always given to the by the at the pipe attachment points to the metal supports. These areas will require an additional loop from below - as shown in the diagram.

• Special attention is always required for massive water supply components - taps, latches, flanges. It also requires the installation of a cable according to a special scheme - see the figure.

• The next important issue is the placement of the temperature sensor. In no case should it be located in the immediate vicinity of the heating cable, otherwise the entire control system will simply lose its meaning, since the sensor should accurately record the temperature readings precisely inside the pipe. The approximate schemes of its location are shown in the figure.

• Under the sensor, the surface of the pipe must be glued with aluminum tape, and it is fixed to the installation site. Normally, the coldest place of the pipeline is chosen to install the sensor.

Installing the heating cable inside the pipe

In some sections of the pipeline, it is simply not possible to install the cable after the px ram decay, for example, in the passages through the slabs, the base, the concrete rings of the well and , , , , cable installation technology inside the pipe.

To do this, purchase a special cable, which can be used in such conditions - with a particularly reliable insulation, round section. The kit must include a special gland assembly - threaded bushings and washers with located between them with a conical or cylindrical rubber seal.

• Before installing the cable, all the sanitary equipment is immediately put on it in the required sequence, in accordance with the instruction, and only then goes switching with the "cold" wire.
• At the cable entry point, install a tee into the water pipe, into which the seal bushing is screwed.

• Then the cable is very carefully inserted into the body of the pipe for the specified length. It is necessary to take into account that thus only heat the straight pipe sections or have minimal bends that will not interfere with the free passage of the cable. Neither case is allowed to pass the cable through valves, taps, latches, or connection areas where protruding threads of thread inside may damage the integrity of the insulation.
• After cable has been inserted , the packing jig completely is twisted and crimped to prevent depressurization of the water supply system.

With all the advantages of such a heating cable installation technology, has and many drawbacks. The main of them is a decrease in the overall reliability of the water supply system, as there is an extra tapping point, narrowing of the internal lumen of the pipe and the often-difficult problems when installing the cable on extended or curved sections.

If this type of installation is chosen, it should be specified in advance whether the heating cable has the appropriate certification for use with drinking water.

Thermal insulation after laying the cable part

Heating the water pipe with a cable only in that case will have some sense if there is a subsequent thermal insulation of the pipes.

• Special materials are used for this purpose, made in the form of semi-cylinders or split cylinders made of mineral wool, polystyrene foam, foamed polyurethane, or rubber , other traditional thermally insulating materials with high thermal resistance.

• It is recommended to install the thermal insulation parts as soon as the cable is laid, thus reducing the risk of accidental damage. Before installation, it must be ensured that the insulating material is completely dry, since the presence of moisture will significantly reduce its effectiveness.
• Installation of thermal insulation is carried out with the utmost care, so as not to damage the surface of the heating cable and do not displace it in the correct position on the pipe. All parts must be fixed in place and with each other in the manner established for them. Seats of joints, in the presence of slots, it is necessary to sprout with mined and glue it with waterproof tape( if using thermal insulation with an external foil coating, the joints are glued with aluminum tape).
• In construction practice, the following thicknesses of heaters for heated sections of water pipes are considered:

- For diameters ½ and ¾ inch- 20 mm;

- Ø 1 and 1¼inch -30 mm;

- Ø 1inch-40 mm;

- Ø 2 inch-50 mm;

- Ø 2½ inch-65 mm.

• After completing the installation of cylindrical parts of thermal insulation, we must not forget about the quality protection of them from the penetration of moisture from the end.

After finishing the work on thermal insulation, it will be possible to connect the heating system to the power network and conduct a test run. If a thermoregulation system is installed, the is configured to maintain the temperature in the pipe at level 3 of the - 5 ºС.

Well-planned installation of the water heating system on is very long to rid the host of the house of the "headache" according to water of possible freezing of pipes.