In winter, during severe frosts, owners of country houses risk being left without water supply. Ice jams in the external water supply will not only leave residents without a shower, an efficient system for supplying water to sinks and other amenities of civilization, but will also cause damage to the pipes.
Agree, the prospect is unattractive. It will be possible to prevent such a development of events if you install a heating cable for the water supply along with the pipes and connect it to the electrical network. It is quite possible to carry out all the work yourself.
We will tell you how the heating element works and describe the main parameters for choosing it. We will also consider in detail the methods of installing the heating cable and illustrate the stages of work with visual photographs.
It is reasonable to argue that you can easily do without. It is enough to find out the level of soil freezing in the area, and then, based on the indicators, dig a trench of the required depth. Usually this is 1.5-1.7 m for the middle strip, depending on the type of soil.
Pipes buried at such a depth and insulated do not freeze, since the surrounding soil has a positive temperature (let's say + 2-4 ° C).
However, not all so simple. In wetlands or areas close to water bodies, high groundwater levels are a common occurrence. This means that during floods or snow melting, communications will be flooded, which will negatively affect their functional properties.
If you bury the pipes only half a meter, but at the same time connect the electrical cable and, then you won’t have to dig deep ditches.
It happens that in severe winters even deep-rooted areas freeze. Living in a house without automatic water supply from a well becomes less comfortable and sometimes even impossible. We have to carry out emergency repair work
Let's not forget about the critical areas that are most susceptible to the effects of cold - the places where the pipeline enters the house. If the building is built on a pile-screw foundation, then underneath there is an open section of the pipeline, which is easiest to insulate with a heating cable.
Conclusion: if it is technically possible to install a heating system for a water supply system, you should definitely use it, at least for the sake of insurance against freezing.
When contacting a specialized company, you may encounter some variety of offers. Let's look at the assortment.
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Depending on the type and technical characteristics, heating cables are used to heat drains and tanks. The main purpose is to protect liquids from freezing by increasing the temperature.
Heating systems are relevant for external communications, that is, for use in the ground or in the open air.
The basis of its operation is the ability of the cable to convert electricity into heat. The wire itself cannot transmit energy, as power analogues do. He only accepts it, and then gives off heat to the pipe (tray, gutter, tank, etc.)
Heating systems have one useful ability - zonal application. This means that you can take a set of elements and assemble a mini-system from it for heating a separate area, without connecting to the entire network.
This results in savings in materials and energy. In practice, you can find miniature “heaters” of 15-20 cm, and 200-meter windings.
The main components of the heating cable are the following elements:
Offers from different manufacturers may differ in nuances - the alloy of the core or the method of protection.
Shielded types are considered more reliable, equipped with foil protection and containing 2-3 cores instead of one. Single-core products are a budget option, which is good for assembling systems for short sections of water supply (+)
To improve the characteristics, the copper braid is nickel-plated, and the thickness of the outer layer is increased. In addition, the PVC material must be moisture resistant and not susceptible to ultraviolet radiation.
All heating systems are divided into 2 large categories: resistive and self-regulating. Each type has its own area of application.
Suppose resistive ones are good for heating short sections of pipes with a small cross-section - up to 40 mm, and for long sections of water supply it is better to use (in other words - self-regulating, “samreg”).
The principle of operation of the cable is simple: a current passes through one or two cores located in the insulating winding, heating it. Maximum current and high resistance add up to a high heat dissipation coefficient.
Pieces of resistive cable of a certain length that have a constant resistance are available for sale. During operation, they give off the same amount of heat along their entire length.
A single-core cable, as the name suggests, has one core, double insulation and external protection. The single core acts as a heating element
When installing the system, it must be remembered that the single-core cable is connected at both ends, as in the following diagram:
Schematically, a single-core connection resembles a loop: first it is connected to an energy source, then it is pulled (wound) along the entire length of the pipe and returned back
Closed heating circuits are more often used for or for the installation of “warm floors”, but an option applicable to plumbing also exists.
A special feature of installing a single-core cable on a water pipe is that it is laid on both sides. In this case, only the external connection type is used
For internal installation, one core is not suitable, since laying the “loop” will take up a lot of internal space, and accidental crossing of wires can lead to overheating.
A two-core cable is distinguished by the separation of the functions of the cores: one is responsible for heating, the second is for supplying energy.
The connection diagram is also different. In “loop-shaped” installation there is no need: as a result, the cable is connected at one end to the power source, the other is pulled along the pipe
Two-core resistive cables are used for plumbing systems as actively as samregs. They can be mounted inside pipes using tees and seals.
The main advantage of a resistive cable is its low cost. Many note reliability, long service life (up to 10-15 years), and ease of installation.
But there are also disadvantages:
In order not to spend money on constantly connecting the cable (which is impractical), install a thermostat with sensors. As soon as the temperature drops to + 2-3°C, it automatically starts heating; when the temperature rises to + 6-7°C, the energy is turned off.
This type of cable is universal and can be used for various applications: heating roofing elements and water supply systems, sewer lines and liquid containers.
Its feature is independent regulation of power and intensity of heat supply. As soon as the temperature drops below the control point (assuming +3°C), the cable begins to heat up without outside intervention.
Self-regulating cable diagram. The main difference from its resistive counterpart is the conductive heating matrix, which is responsible for regulating the heating temperature. The insulating layers are no different
The principle of operation of the samreg is based on the property of the conductor to reduce/increase the current depending on the resistance. As the resistance increases, the current decreases, which leads to a decrease in power.
What happens to the cable during cooling? The resistance drops - the current increases - the heating process begins.
The advantage of self-regulating models is the “zoning” of work. The cable itself distributes its “labor power”: it carefully warms up the cooling areas and maintains an optimal temperature where strong heating is not needed.
The self-regulating cable works constantly, and this is welcome in the cold season. However, during a thaw or in the spring, when frosts stop, it is irrational to keep it on (+)
To fully automate the process of turning the cable on/off, you can equip the system with a thermostat that is “linked” to the outside temperature.
There are two ways to install a heating cable - external and internal. In the first case, it is attached along the pipe (or wound around it), in the second, it is wound inside. Both options have active practical applications, so let’s take a closer look at them.
Linear installation of cable along a water pipe is easy. The wire is fixed on one side using heat-resistant plastic clamps or fiberglass self-adhesive.
The holders are fastened at intervals of 0.3 m. Metal fasteners cannot be used. It is not difficult to calculate the length of the cable - it is equal to the length of the pipe that needs to be heated.
Line installation instructions:
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For pipes buried in the ground, the cable is not placed strictly at the bottom or at the top, but slightly offset, which can be called the “8 (4) o’clock position.”
In addition to linear installation, spiral installation is used - the cable is wound along the entire length of the pipe with a uniform pitch. Plus – maximum contact with the pipe surface, minus – increased material consumption.
The pitch between turns can be changed depending on conditions. For example, for areas subject to severe freezing, it is reduced - thus, the entire surface of the pipe will be heated to the maximum
The wound method is relevant for pipes of medium and large diameter - sewer, drainage, but is also used for heating water pipes.
The internal installation method is not suitable for all pipes, but only for water pipes with a cross-section of more than 40 mm. In pipelines with a smaller diameter, the cable will partially block the flow of water. It is difficult to equip a long pipe with internal heating, but for sections several meters long this is one of the best ways.
It is easiest to pull the cable in vertical sections - from top to bottom. The procedure takes place using a tee and a sealing coupling, which prevents the cord from slipping.
In some cases, it is more rational than external - for example, for repairs or replacement of elements. It is not difficult to insert and connect a finished system; it is much more difficult to assemble it.
You can learn how to properly prepare the wires for insertion into the pipe from the following instructions.
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To get to the core of the self-regulating cable, first remove the top layer of polymer insulation
Using a sharp thin object (a needle, a knitting needle), we unravel the protective grounding braid
Using pliers or scissors, remove the corner from the evenly cut end of the cable (without removing the internal insulation and matrix)
We select a coupling of suitable diameter and cut it so that it completely covers the internal insulation
To ensure that the coupling fits tightly around the end of the cable, we blow it from all sides with a hair dryer.
While the coupling material has not cooled down, use pliers to carefully clamp the “excess” material and glue it together
We put on the cap and heat it with a hair dryer. We heat from the end, carefully pulling the cap onto the cable
When heating with a hairdryer, glue may come out - it must be removed. The cable is ready to be connected to the pipe
Regardless of the type of cable, it is necessary to carry out insulation. Thermal insulation is mounted on top of the heating system and water pipe. If the water supply along with the heating cable is not placed in a sealed “cocoon”, the heating will go in all directions, that is, mostly into the air.
The thickness of the thermal insulation layer is selected depending on external factors. Let’s assume that for installation in the ground, a 20-30 mm layer is sufficient, while for above-ground installation, insulation of at least 50 mm in thickness will be required
Expanded polystyrene or foamed polyethylene act as reliable and effective insulation materials. They are moisture resistant and provide some protective cushioning for the pipe, but also need protection.
For this reason, the “pipe-in-pipe” design is often used, when water pipes located in the ground or in the air, together with insulation, are placed inside another pipe of a larger diameter.
Before going to the store, be sure to check the diameter of the water pipe, the length of the area that needs heating, the lowest possible air (ground) temperature - this will make it easier to make a choice, because there are really a lot of offers.
So, let's pay attention to the following points:
A cable with polyolefin insulation may be suitable for a sewer system, but for internal installation in a water pipe we recommend protection made of fluoroplastic. For outdoor installation, a fluoropolymer is suitable, which will protect both from moisture and ultraviolet radiation.
If it is necessary to heat small-diameter pipes, a low-temperature type conductor is suitable. It heats up to + 65 ºС, maximum power is about 15 W/m
Medium temperature systems are suitable for larger diameter pipes. Maximum heating temperature is +120°C, power reaches 33 W/m.
High-temperature systems with a maximum temperature of up to +190°C and a specific power of up to 95 W/m are considered the most powerful. However, they are usually not used in everyday life - these are products for industrial use.
The appropriate power can be selected based on the diameter of the pipe. For example, for water pipes with a diameter of up to 2.5 cm, cables with a power of 10 W/m are suitable, from 2.5 cm to 4 cm - 16 W/m, from 4 to 6 cm - 24 W/m, etc.
There are several brands of heating cable that have long proven themselves only from the best side.
Famous products of foreign companies:
Among Russian manufacturers, the company stands out SST
Even a beginner can select and install a heating system for a water supply system. With the help of theoretical knowledge, you will quickly understand the types of cables, and for installation you do not need to master any special skills.
The result of the work may be worthy: you will forever forget about the problem of water freezing in the water supply during the cold season.
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This text may be difficult to correctly perceive without reading my article.
The heating cables in question are designed to prevent water from freezing in water pipes in winter.
First, the output:
The “correct” heating system is a mandatory combination of a high-quality heating cable with a high-quality and high-precision thermostat.
No, even good (modern) heating cables without a thermal relay are suitable for long-term reliable and economical operation, including “samregs” (see my link about them).
Below I will try to explain this, and also tell you how to properly build heating systems.
If the heating cable is installed on top of a water pipe running from the ground into the house, then replacing it if it fails becomes a big problem. Even if this problem is easily solved (for example, with a cable inside a heated pipe), the reliability of this system (especially in cold weather) still has a very high priority - in the winter of 2009-2010 (very severe frosts), a huge number of people had their water pipes frozen.
Therefore, I take maximum reliability and durability of the heating system as my goal.
The heating cables themselves have a limited time between failures, so if they are turned on as rarely as possible, their lifespan will increase accordingly. Electricity consumption also matters (especially when the heating is constantly on).
The main idea:
If the temperature of the pipe is close to the temperature of the water in the well or well, this means that there is no point in heating it, or rather it is even harmful (for the heating cable). Therefore, the heating cable shutdown temperature should be slightly less than the winter (February) water temperature in your well/well ,
which is usually 5-6*C.
How to make the “correct” heating system for water pipes:
We take a high-quality, durable heating cable (it doesn’t matter whether it is self-regulating or not, the main thing is its lifespan and a sufficient number of on-off switches), wind it around the water pipe, as required by the instructions. There, close to the pipe in its coldest place (it is near the surface of the earth), we install a temperature sensor, and on top (in the house) - a thermal relay on which we set the on t of 2-3 degrees Celsius and the off t of 3-4 degrees. These numbers are because in winter (at the very coldest) the water in a well or well has a temperature of 5-6 degrees.
We thermally insulate the entire pipe (together with the sensor) with insulation with a thickness of at least 20 mm (in fact, for your wallet in the future, the more, the better). And we correctly connect all this to the 230V network.
The result was the most optimal option for using a heating cable to heat a water pipe according to the criteria of minimum electricity consumption and maximum cable life.
When using a special heating cable inserted inside a water pipe, nothing fundamentally changes.
If you use a heating cable without a thermal relay (including a self-regulating one), then the result is an overconsumption of both energy and cable life. Moreover, many times compared to the approach I described. And also - the impossibility of monitoring the performance of this entire subsystem, which is no less important!
About choosing the power of the heating cable for water pipes:
If you do everything correctly (as I described above), then saving on the power of the heating cable is almost pointless, because the system will turn on quite rarely and with a higher power it will simply heat up faster, consuming approximately the same amount of energy as with a lower one. Power reserve won't hurt.
In general, it is considered this way: if the cable is installed inside the pipe, then 10 W/m is enough, and if outside, then 17 W/m. I would take a little more for reserve.
About protective subsystems.
Due to the fact that cases of heating cables and even HDPE pipes melting are quite common, it is necessary to understand that such a cable must be equipped with a 1-2 Ampere machine, and not 6 or 16 Amperes. Also, an RCD would not hurt in this circuit.
For meltdowns, see and.
About the thermostat and temperature sensor:
Ideally, you need a small sealed sensor with a digital thermostat located in the house.
If we do not take into account reliability (it is unknown to me), then the following would be suitable: a TR-35M thermostat, or a TSTAB thermostat.
Personally, my boiler and " " are controlled by RT-12-16. Satisfied.
It is better to seal the temperature sensor itself.
What not to do:
1. It is not necessary, for example, to use “Nelson EasyHeat resistive cable” without a thermal relay to heat the pipe coming from a well or well into the house. Why?
Because here the cable will turn off only at +13 degrees. And in wells, such a high temperature most likely never occurs even in summer. This means that the cable will wastelessly heat up the borehole/well water! And turning it off manually, for example, in early spring, risks freezing your water supply pipe on a cold night.
2. The temperature sensor should not be installed in close proximity to the heating cable, otherwise the system will not work properly. It must be placed on the opposite side of the water pipe from the heating cable and carefully insulated from the heating cable (but not from the pipe!). This, by the way, is the most unpleasant drawback in the heating system - the heater and meter should be as far away from each other as possible, and this is really difficult to achieve.
3. You cannot use insulation that can get wet (cotton wool). Also, you should not let the earth compress the insulation too much. In either of the two cases, it will become poorly insulated.
You can use, for example, foamed polyethylene (necessarily with closed cells) with a rigid pipe on top. For example, on a HDPE-32mm pipe you put a standard “stocking” of insulation, on top of another stocking of a larger diameter and put it all into a sewer pipe with a diameter of 110mm. After such installation, you can probably foam the remaining space (I foamed it to a depth of 1.3 meters, one 750g bottle of foam was just enough). It is better to foam with two-component foam; regular foam may not all freeze inside, because... it does not have access to moist air, which ensures the hardening of the foam.
Although, it is clear that with very good insulation, the temperature of the pipe may not drop to 2-3°C at all, but no one can guarantee this. At a minimum, due to uncertainty about the preservation of the properties of the insulation throughout the entire service life of the system (several decades).
Monitoring the performance of the system with a heating cable:
If you ever see that the temperature is lower than the set temperature, this means that the system is not working correctly or has failed.
Also, you can periodically check the performance of the system by temporarily changing the switching temperature of the thermal relay ("adjusting" it to the temperature of the pipe) and observe the switching on/off of the relay by its click and indicator.
There is also an 8-year practice of another of our forum members, confirming this theoretical study of mine (the link was lost when the forum “engine” was changed). If anyone finds it, please let me know.
Notes:
1. As a rule, there is no need to heat sewer pipes. They only need to provide the correct, strictly optimal slope.
2. If the street horizontal part of the water pipe is laid deep enough, or insulated (including snow), then it is most likely not necessary to heat it. But only the control system provides guarantees...
3. On a related topic you can read:
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4. And here is an almost free heating cable for DIYers:
kostiksamara said:
The power supply from the computer is 300 watts, I took a 12V (15 Ampere) output wire in PVC insulation with a cross-section of 1mm. The length of the loop is 20 meters, that is, 40 linear meters. the wire feels warm to the touch, 40 degrees
And also a whole topic:
5.
6. If a heating cable is used to be inserted into a water pipe, then for safety reasons its coupling must be grounded. I also consider it desirable to make an additional potential equalization system in the bathroom - DSUP (in addition to the main SUP). The presence of a 10-30 mA RCD is implied.
Protection of water and sewer pipes in winter often comes to the fore, especially in regions with difficult climatic conditions. Sometimes it is necessary to install a self-regulating heating cable for the water supply if an error was made when calculating the depth of soil freezing. Depending on the heating system, the wire can run either through the outside or inside of the pipe. The consequences of freezing of communication channels can be critical, because frozen water tends to expand, which leads to pipeline breaks with ice ridges.
Read in the article:
Water communications operating in low temperature conditions require constant heating, because the water in them is not always in motion. During downtime, ice inclusions may form in some sections of the pipeline and prevent further movement of water. When the freezing area reaches a certain size, a breakthrough will occur. A heating cable for water supply can prevent this problem at the stage of the first ice formation. Unlike resistive wires for heating pipes, which are under constant voltage and consume quite a lot of electricity, a self-regulating cable has features that allow it to be saved.
The main distinguishing feature of a self-regulating wire from a resistive one is the supply of increased voltage only to those sections of the pipeline where the temperature has dropped below the specified values. Although the self-regulating heating cable for the water supply is also constantly under voltage, it is almost half as low as that feeding the resistive conductor.
This device for heating water pipes has a complex, multi-layer structure:
Expert opinion
ES, EM, EO design engineer (power supply, electrical equipment, interior lighting) ASP North-West LLC
Ask a specialist“Carbon, depending on the ambient temperature, can change its conductive properties. Therefore, the carbon conductive matrix is the main element of the self-regulating cable. As the temperature of the pipe drops in a certain area, the fiber cools and its ability to conduct current increases. Due to this, the cable is heated only in the right places and at the moment of critical danger.”
Thanks to the properties of carbon fiber to change conductive characteristics under the influence of temperature changes, maximum efficiency is achieved.
Important! Using copper conductors made from rigid wire for self-regulating cables is impractical, because with frequent bending such wire quickly becomes unusable.
Using a self-regulating heating wire for water supply will eliminate the need to use temperature sensors, which often fail. To connect such a cable to the network, no additional equipment is required.
In the long term, the use of a self-regulating heating cable for water supply will be more economical than the use of a resistive one, although its price is higher due to the complex design and materials used in the manufacture.
The only advantage of a resistive conductor is that using it for already frozen pipes will be no less effective. But in practice this is rare, because if the pipe is completely frozen, then most likely it is already damaged.
The main advantages of self-regulating heating wiring for water supply can be considered by comparison with resistive wiring:
Important! Although changing the length of the wire is considered normal practice, greatly increasing its size is impossible. The maximum length of such a cable can reach 100-150 meters, depending on the cross-section of the copper conductor.
When purchasing a heating cable, you need to understand for what purposes it will serve; the choice of wire should be made taking into account:
Related article:
In our review, we will look at why the cable is needed, what role it will play in winter, the principle of operation, installation features, average prices, useful tips and recommendations from experts.
Construction rule - SP 40-102-2000, recommends laying water and sewer pipelines at a depth exceeding the soil freezing level. However, there are objective reasons under the influence of which this cannot be done (the depth of freezing in winter is too great or the structure of the soil does not allow deepening to a sufficient extent). In this case, it is recommended to use a self-regulating heating cable or its resistor equivalent.
To start calculating the required self-regulating cable, you need to have data on:
The calculation is made using the formula:
L cable = K zap × L tr × Q beats / P beats, Where
L cable – calculated length of the self-regulating cable;
K zap – safety factor;
L tr – heated length of the pipe section;
Q beat – specific heat loss depends on the diameter of the pipe, the thickness of the insulation, as well as the temperature difference between the running water and the environment;
P beat – maximum cable power.
But for home purposes, you can use a simple method for determining the power of the wire, so for pipes with a diameter of up to 32 mm, 16 W/m is enough. A pipeline with a diameter of up to 110 mm is capable of heating a cable with a power of 24 W/m.
| Drawing | Actions |
|---|---|
 | A self-regulating heating cable for water supply is applied to the top of the pipe along its entire length. |
 | The top is fixed with aluminum self-adhesive tape. It is important to achieve the tightest possible fit of the wire to the surface of the pipe. |
 | When the entire wire is glued, the fixation should be strengthened with plastic ties every 20 cm. |
 | Thermal insulation material is placed over the pipeline. It is needed to preserve the generated heat. |
 | The seam along the edges of the thermal insulation must be sealed with aluminum tape. |
 | If the pipe is fastened with clamps, then the wire must be laid at the joint, between its rubber gaskets. This will avoid damage, even if the clamp is tightly fixed. |
 | In cases where it is necessary to provide heating for a tap or valve, the wire, even for a small pipe diameter, must be wrapped around the specified unit and tightly secured with ties. |
| Drawing | Actions |
|---|---|
 | The pipe should be covered with aluminum tape in advance. This is necessary for better heat distribution from the wire. |
 | Lay the wire along the pipe and place aluminum tape over it. Cold water is always displaced by warm water to the upper zone of the pipe, which is why the conductor is laid on top. |
 | Secure with ties. This is important to do because the aluminum tape does not hold the cable as securely as required and can be accidentally torn off by physical contact. |
 | Next, attach the thermal insulation according to the same rule as above. |
Pipes with a diameter of over 50 mm must be wrapped with wire in such a way as to ensure heating of their entire area.
| Drawing | Actions |
|---|---|
 | This type of heating occurs for large diameter pipes and is often used for sewerage. It is possible to lay the wire inside the pipe if access to its surface is closed (it is buried). |
 | The pipe must be insulated from the outside with thermal insulation material. |
 | All joints must be covered with aluminum tape for better heat retention. |
 | The heating wire is laid along its entire length; it is inserted and removed using a special gland. This seal is designed to contain water pressure. |
If the diameter of the pipe in need of heating is less than 50 mm, but more than 32 mm, it is better to opt for a more powerful wire.
When you are installing a self-regulating conductor along a pipe and you come across a node that requires more careful winding, it will be easier to leave a supply of cable and move on, fixing it on the remaining section, and return to difficult places later. This point is also important for the possible subsequent replacement of a tap or valve. By removing the insulation and cutting the ties, the wire will be released, and nothing will hinder the removal of the assembly.
For pipes of large diameter, the cable on which is fixed in a screw-like manner, it should be covered with aluminum tape as carefully as possible, this will reduce heat loss.
If you want to heat a sewer pipe, and they usually have a diameter of at least 100 mm, then it makes no sense to run the heating wire in a helical manner, since there is no high water pressure there and all the liquid moves along the lower part. It is enough to cover the surface of the pipe with aluminum tape to the middle of the diameter from the bottom, and run the cable in two lines along the bottom.
Based on the listed possibilities for using a self-regulating heating cable for water supply, we can summarize the following:
Today, heating cables are widely used both in everyday life and for industrial purposes. These products are intended not only for creating a heated floor system, but also for heating pipes in the winter. It is very important to choose the right type of conductor (self-regulating or resistive), design, and power. In this article we will tell readers how to choose a heating cable for water supply and drainage.
First you need to decide on the type of heating conductor. Resistive cable is less practical since it has a constant power and a fixed length. The disadvantages of this product include its tendency to overheat and fail. The main advantage is the comparatively low cost. You can find out more about this from our article.
Self-regulating heating conductor has more advantages, so choosing it will be the right decision. The main advantages of the product: resistance to heat, the ability to save energy, there are no restrictions on the length of the heating system and, equally important, resistance to overheating. The only reason why choosing a self-regulating heating cable is not always appropriate is the higher price (in some cases, resistive wire is more appropriate, for example, for heating containers and small-diameter pipes).
Still, we believe that the right decision would be to choose a self-regulating heating cable, especially for heating water pipes and drains. Next, we will dwell in more detail on the criteria for choosing this type of heating conductor.
So, the first thing you need to decide on is the design features of the product. may include two copper conductors, a matrix, an insulation layer, a braid and an outer sheath. When choosing, be sure to pay attention to whether there is a braid on the thermal cable or not. If not, this is a budget option. The braid makes the wire stronger, more resistant to mechanical damage and also grounded. Therefore, choosing this option would be the right decision.
You can learn more about braiding from the video:
Another important point is the type of external insulation. For domestic use (sewage), it is quite enough to choose a heating cable with an insulating layer in the form of polyolefin. If you want to use a cable heating system in production, and resistance to aggressive environments and ultraviolet radiation is important, we recommend choosing a heat cable with fluoropolymer insulation. For water supply, if the conductor will be laid in a pipe, it is better to choose a product with an outer sheath made of fluoroplastic.
Important! It is not always possible to use a conductor intended for heating pipes outside, which can be used for laying inside. Please check this point with your sales consultant!
The next thing you need to pay attention to when choosing a heating electric cable for water supply and drainage is the temperature class. A low-temperature conductor can heat up to 65˚C, while its specific heating power is no more than 15 W/m. This type of design is best chosen to protect small-diameter pipes from freezing. A medium-temperature thermal cable heats up to a maximum of 120˚C and has a power of 10 to 33 W per linear meter. It is better to choose it for gutters, medium-diameter pipes, and roof heating. The high temperature heating cable can reach temperatures of 190˚C with a power density of 15–95 W/m. This type of design is not suitable for a private house or cottage; its choice is rational for industrial conditions, heating large-diameter pipes.
Having familiarized yourself with the power and application of a thermal cable, the question arises, what characteristics should a conductor have for a certain pipe diameter. So, we recommend choosing a heating cable based on the following indicators:
Important! The choice of heating cable power must be approached responsibly. Insufficient power will result in the heating system not being able to do its job, and excessive performance will have a negative impact on energy consumption.
In winter, the owner of a country house risks being cut off from the well and artesian well. Ice jams in the street water supply will not only turn off the shower, kitchen and toilet, but also damage the pipes.
Insulation is not a guarantee against freezing. As long as the water moves into the house, forced by the pump, it will not turn into ice. At night in severe frost and when there are no residents during the day, the standing liquid will clog the pipe in a few hours.
Until a cable for heating pipes was created, the street water supply route had to be buried deep into the ground, falling below the freezing mark of the soil. Despite this, there was still a vulnerable section on the route - the transition of the pipe from the ground to the house. It would be good if the route was laid by competent builders before the foundation was poured and reached the surface under the building. The heat from the house prevented the liquid from freezing on this isthmus. If the entry was made from the street, then no insulation tricks could save the situation.
Today, having bought a heating cable, you don’t have to worry about this problem. In any frost, the heat generated by the electric current will prevent the water from freezing and clogging the pipe. We will talk about what types of heating cables can be purchased on the market, what their design is, the principle of operation and installation methods in this article.
There are two types of cables designed to protect pipes from freezing:
Resistive heating cable is available in two versions: single-core and two-core. The design with one conductor is quite simple: nichrome wire is filled with fluoroplastic insulation, over which a copper shielding braid is wound. The outside of the cable is covered with a heat-resistant plastic sheath.
A two-core resistive cable consists of two nichrome conductors that generate heat when current passes. Some systems use two wires with different purposes. One of them is heating, and the second is cold, conductive.
Where a foil screen is used rather than a copper braid, a drain core is installed. It contacts the foil and removes from it the electrical potential generated by electromagnetic fields. This core is used as grounding.
Considering the existing types of heating cable, we will focus on an improved modification of the resistive one. It was called zonal and was developed to eliminate the disadvantage of two-core cables. They cannot be cut into pieces or shortened by more than 10% of the total length. This requirement created and still creates inconvenience during installation.
Zonal cable design
By design, a zonal cable is a system of wire spirals wound on insulation and connected by current-carrying busbars. Trimming the spirals at the points of the contact protrusions does not interfere with their operation and makes it easy to select the thermal power. We also note that the minimum permissible length of such a cable is 1.5 meters.
The most popular type of pipe heating cable today is self-regulating. The main part of its design is a semiconductor conductive matrix. It changes electrical resistance in proportion to changes in ambient temperature.
Self-regulating heating cable device
The colder the soil or air surrounding such a cable, the greater its resistance becomes and, accordingly, more heat is generated.
When choosing a heating cable for pipes, it is important to know the pros and cons of each type on sale. Let us briefly list them.
Single-core cable is in demand for the following reasons:
The disadvantages include the need to accurately calculate the length, since it has to be laid so that the other end returns to the power source. In addition, as we have already said, working with resistive cables (except for zonal cables) is complicated by manufacturers’ ban on cutting. For this reason, when purchasing, you need to know exactly the required length and power.
Another limitation for all resistive systems– inadmissibility of crossing sections of the cable line. In this case, the temperature at the contact points rises sharply, which can lead to melting of the insulation and burnout of the wire.
A two-core resistive system is easier to install than a single-core system, but it is also more expensive. When laying such a cable line, you do not need to pull it back to the outlet. Simply attach it to the pipe and cover the top with a heat insulator. In terms of durability and protection from external influences, single-core and two-core tube heating options are the same.
Self-regulating heating cable (SGK) does not have the disadvantages of resistive, but its cost is significantly higher. The high price is partially offset by simple installation, the ability to cut and shorten, as well as cost-effectiveness. If the water supply runs underground below the freezing mark, then you just need to purchase a small piece of SGC cable and place it in the most critical area - the transition of the pipe from the ground to the house.
The overlap of current-carrying turns of a “smart” line is not dangerous. There will be no overheating at the contact points. The semiconductor matrix will automatically reduce the temperature there. In addition, when a self-regulating cable operates, the coldest areas heat up more strongly, while in others the temperature is maintained at a lower level. Due to this, energy savings are achieved, in contrast to resistive routes operating at full power along the entire length.
SGK between two water pipes laid at a depth of half a meter at the entrance to the basement of the house.
From the above, we can conclude that a resistive cable will be more appropriate for constant heating of large areas, within which there are no large differences in temperature conditions. Its use will allow you to get the desired result without unnecessary overpayments. Often such a cable is used when installing heated floors. Self-regulating cable, despite its higher cost, is suitable for most tasks in private housing construction and will justify itself due to its efficiency, ease of installation and operation.
In practice, two methods are used for installing heating cables for pipes:
Outdoor installation is easier than indoor installation. It does not reduce the throughput of the pipe and allows you to easily replace the damaged section if necessary.
For outdoor installation, linear installation is more often used. In this case, the cable is rolled out along the entire length of the pipe and fixed to it using adhesive aluminum tape.
The thermostat should always work in conjunction with a resistive (single or two-core cable). Its sensor is placed on the pipe and secured with tape to its surface. Having completed the installation, the route is covered with thermal insulation and covered with soil.
Thermostat with sensor is a must-have addition for a resistive heating cable
When installing on a plastic sewer pipe, the attachment points are first wrapped with adhesive aluminum tape and only after that the cable is fixed to them. This solution makes the heat distribution more uniform, protecting the plastic from overheating.
Cable installation methods
When laying a water supply in areas with a harsh climate or installing heating on roof gutters, ring laying is used in increments of 5 to 15 cm. This method allows you to increase heat transfer per 1 linear meter of the route.
It should be noted that winding the heating cable onto pipes is only applicable for two-core and self-regulating cables. You can’t use a single-core wire for this kind of work. At the intersection points of the turns it will overheat and burn out.
The connection diagrams for resistive single- and double-wire traces to the power source are similar. The only difference is that the single-core wire is laid in the form of a large loop, and its other end returns to the electrical outlet.
With a two-core cable, both ends can be immediately connected to the network. A separate socket must be provided for a thermostat with a temperature sensor.
The self-regulating heating cable does not require a temperature sensor. It reacts to temperature changes without external devices, proportionally increasing or decreasing heat transfer. Therefore, after installation, it is directly connected to a 220V power supply.
This is what the installation kit looks like (heat-shrinkable tubes and plug, connecting sleeves) and a set of tools for connecting the SGC to the network
The only nuance that requires a detailed explanation is the preparation of the current-carrying conductors of the SGK for connection. It consists of the following operations:
As an alternative, manufacturers offer ready-made heating cable kits, where all of the listed connection operations have already been completed at the factory. All you have to do is choose a kit with the appropriate characteristics and the required length, carry out external or internal installation and plug the plug into the socket.
An example of a finished heating system intended for installation inside a pipe. The approximate price of such a kit for 2018 with a self-regulating cable 10 m long is 4-7 thousand rubles, depending on the manufacturer and power.
To correctly select the power (W/m) depending on the depth of the trench, pipe diameter and air temperature, you can use the data in the table.
If it is impossible to carry out external installation on a water supply system (the pipe is filled with concrete or insulated with bitumen), use an internal gasket. A single-core cable is not suitable for this work, so use a two-core or self-regulating one.
Internal installation in sewer pipes can be done not with any type, but only with a special heating cable with reinforced insulation and a screen. If you need to lay a heating line inside a drinking water supply, then for this purpose you will have to buy a so-called food cable.
This is what the installed and crimped cable entry sleeve looks like
The internal gasket has a number of limitations. It is not allowed if there are rotating elements, cranes and mechanical joints in the route. To do this, a special tee with a sealed coupling is cut into the pipe. Through it, the working end of the cable is inserted into the pipe to the required length. After testing the system, the coupling is tightened with a wrench and rubber seals make the entry point airtight.
