Heating of the roof and drains: calculation, design and installation of anti -icing cable systems

Welcome to "All About the Roof," where we explore the most important facets of protecting and maintaining roofs. This article focuses on a vital topic that many building managers and homeowners overlook: heating roofs and drains with anti-icing cable systems. Snow and ice buildup on roofs in colder climates can result in major problems like leaks, structural damage, and even safety risks from falling ice. By taking proactive measures to avoid these issues, anti-icing cables guarantee that your roof will stay secure and functional throughout the winter.

A thorough understanding of your roof’s layout and the unique climate conditions is necessary for the calculation and design of an anti-icing cable system. In order to dissolve snow and ice before they can accumulate and cause issues, these systems function by producing heat. An accurate installation is essential to their efficiency. You can effectively manage ice buildup and prevent water damage inside your home or building by placing the cables strategically along important areas like eaves, gutters, and downspouts.

When thinking about installing an anti-icing cable system, it’s crucial to speak with experts who can evaluate the particular requirements of your roof. The design and installation process can be influenced by various factors, including the type of roofing material used, insulation levels, and roof pitch. A well-thought-out system not only increases safety but also increases roof longevity by lowering the possibility of ice dams and the associated water damage.

Here at "All About the Roof," our goal is to provide you expert guidance and real-world insights on caring for and safeguarding your roof. Our mission is to arm you with the information you need to make wise decisions about your roofing investments, whether you’re looking into preventive measures like anti-icing cables or need advice on roof repair and maintenance. As we explore the topic of roof maintenance in more detail, you can be sure that your house or building is secure and safe all year long.

The need to use roof heating

Snow, as you may know, causes a lot of issues in addition to being "dizzy, flies, and melts":

1. With its weight, it can damage the roof or the drainage system up to the formation of leaks.
2. Having overcome a critical mass, a snowdrift can slip off the roof slope and fall down, injuring people or animals located near the house.
3. Soft and loose snow very easily turns into a hard dangerous ice: in the afternoon, under the rays of the sun, melting occurs, and at night the water formed freezes. The ice not only blocks the drainage system and creates the danger of its collapse with its weight, but also in the form of icicles threatens the life of passers -by.

Keep in mind that if the roof is inadequately insulated, snow may begin to melt in the winter ("warm roof"). This time, the house’s interior temperature is the reason for the melting. Melted water freezes and forms ice and icicles as it flows to a colder cornice and drain.

Ignore the snow and ice buildup on the roof. However, you can use a more straightforward and contemporary method in place of mechanically removing them: fixing the heaters on the roof and drainage system. This is how the anti-icing system works in its entirety.

The composition of the anti -icing system

The components of this system are as follows:

1. Heating cable. It looks like a regular conductive cable, only the composition has a core of material with high electric resistance. When the electric current passes through it, the energy of the latter turns into heat.
2. Cabbage couplings: connecting and end (plugs).
3. Fasten elements.
4. Weather station. So called a set of sensors – temperature and humidity – allowing to automate the operation of the system. There are models in which individual sensors are used to register melting and rainfall. The anti -icing system of anti -icing, which is not equipped with a weather station, has to be turned off manually: in the presence of precipitation – turn on, in the absence of those – turn off. This, firstly, complicates the life of the user, and secondly, leads to an overexposure of electricity.
5. Distribution system: includes cables – power (for connecting a heating cable to the power grid) and signaling (connecting sensors to the thermostat), as well as installation boxes.
6. Switchboard.

The shield has multiple gadgets:

• The circuit breaker is automatic (VA): if the system is 3-phase, then one for each phase;
• Contactor 4-pole or magnetic starter;
• a protective shutdown device (RCD), which works with current leaks from 30 mA;
• signal lamp;
• Wa for the thermoregulator control circuit;
• Thermoregulator: supplies power to a heating cable at a certain temperature, usually from -8 to +3 o C.

Types of heating cables

There are multiple variations available for the anti-icing system’s main component.

Resistant heating cable

Even though the definition of "resistive" for this kind of cable was tightly set, it is not entirely accurate. Since every warming cable has resistance by nature, it would be more accurate to refer to this particular option as a "unregulated" cable.

The most basic device is the unregulated cable. This is an extended, long-core heating element made of a high-electric-resistance metal alloy (often used by nichrome), isolated and protected by a shielding shell. The following are his advantages:

• has a low cost;
• During the inclusion, it does not cause a significant leap of current strength (the so -called starting current).

1. Has constant heat performance. Because of this, those areas of the roof that are currently in the warmth at the current moment are overheated, and even at the expense of the user (power output). In addition, with insufficient heat generation, an unregulated cable may overheat and burn. Especially overheating are prone to the seats of the overwhelming of two cable lines.
2. It is impossible to reduce the length of the cable in an already mounted system, since its electrical resistance will decrease and, accordingly, the current strength in the circuit will increase.
3. Clean power also depends on the length.
4. With a break in heating, the entire cable becomes inoperative.

There are two performance levels of unregulated resistive cable available:

• one -core;
• Two -wire.

In actuality, a single vein—albeit folded in half—was also utilized in the two-core cable. This allowed for the following victories:

1. The need to close the contour, pulling the second end to the connection point. Thus, a two -core cable is laid in one thread, and not in two, as one -cereal, therefore, the danger of a overflow is excluded when the large masses of snow. It should be noted that the system with such a cable is more simple in design and installation.
2. Currents flowing in the cable veins, and essentially in two halves of the same core – have opposite directions, therefore the magnetic fields they generate mutually destroyed. One -core cable in close proximity to a person (for example, if the attic is a residential) with its electromagnetic field can harm health.

Zonal resistive cable

Although the heating core is also composed of nichrome, the cable’s construction is a little different. It is composed of two separate conductive cores, phase and zero, with warming the vein wound in a spiral pattern around them. Simultaneously, the nichrome conductor is split into segments that are joined to conductive veins at their ends. As a result, the zonal cable is made up of numerous heating segments that are linked in parallel to the mains. The following benefits result from this:

1. The length of the cable can be reduced, since the current strength at the entrance is reduced, and the linear power with any length remains constant.
2. With a break in heating core in any place, other areas remain working.

As one might expect, there is a zonal resistive cable that is more costly than normal.

Self -regulating cable

Similar to the zonal cable, this one also has two conductive veins, but the heating wire is composed of an entirely different substance called the "matrix," which is a unique polymer with semiconductor qualities. It is placed between the conductive veins rather than around them. The matrix is unique in that the more heated it is, the fewer active conductive tracks it has because of its temperature-dependent electrical resistance.

Ultimately, the polymer becomes a dielectric—that is, it shuts down—when heated above a certain point, but the regions that remain at a suitable temperature keep working. It is clear that self-regulating cables have the following benefits:

1. Burning in places of overlap or due to insufficient heat generation is impossible physically.
2. When overheating of the roof in any place, the corresponding section of the cable automatically reduces the power of heat emission, so that electricity is consumed very rationally. As practice has shown, on average, a system based on a self -regulating cable consumes 2 times less electricity than equipped with an unregulated analogue.
3. All live routes are, as it were, connected in parallel, so the length of the cable can be reduced. The cliff of the matrix does not lead to the failure of the cable.
4. The service life is about 30 years. This is several times (!) more than an unregulated cable.

However, there are drawbacks:

• The cost of a self -regulating cable is 3-5 times higher than the cost of the unregulated (240 – 660 r./Pog.m against 90 – 150 r./Pog.m);
• In the cold state, the matrix has a very low electrical resistance, so when turned on, there is a high start -up current (you have to use more expensive protection devices).

In order to avoid damage from snow and ice buildup, heating roofs and drains requires careful planning and installation of anti-icing cable systems. The key procedures for figuring out, creating, and setting up these systems are covered in this article. Everything matters, from figuring out how much heat is needed given the local climate to selecting the appropriate cables and where to put them. Ensuring efficient melting of ice and snow through efficient heat distribution across the roof and drains protects the structure from potential water damage and keeps the roof functioning at its best all winter long."

Design and calculation of the anti -icing system

Creating a roof heating system is not an easy task, particularly since every situation calls for a unique solution. It is necessary to design specialists. However, with the general guidelines to still acquaint yourself with the future owner. if nothing else, to avoid falling for a dishonest vendor trying to push an excessively costly system.

Thus, they roughly make the following in general:

1. Develop a scheme for laying a heating cable. If the roof is “cold” (that is, well -insulated) and softer, you can limit yourself to the heating of the drainage system. On the “warm” roof, the heating is also subject to the edge of the roof, the border of which is determined as follows: 30 cm from the line of intersection of the planes of the outer wall and slope are laid up along the slope. On the roofs with a significant bias, due to the high probability of the collapse of the snow mass, this border should be attributed even higher by 15–20 cm. If the roof is flat, then the cable is laid along the perimeter and in the drainful funnels.
2. With a large angle of inclination of slopes, the heating cable is also provided with a zigzag between the roof edge and the snow retainer, which should be installed on such a roof without fail (due to the high probability of slipping snow mass). Particular attention should be paid to places where two parts of a slope are joined with different slope – these are valleys (sewage faces) on flat roofs and yendovs on gable. The same can be said about the place where the roof adjoins the wall. Here, ice forms especially often. The cable must be laid in the form of an elongated loop at 2/3 of the height of the valleys or valley. In the case of the roof adjustment to the wall, the cable must be laid 5 to 8 cm from the latter, while the distance between the threads of the elongated loop should be 10 – 15 cm.
3. If the roof is not equipped with a drain, the cable on its edge is placed according to the “dripping loop” scheme (with a large slope) or “dripping line” (with a small slope). The idea is as follows: the loop is suspended so that the water from it drips directly to the ground. For styling according to the “dripping loop” scheme, the cable must have a allowance of 5 – 8 cm.
4. Along the gutter up to 15 cm wide, one cable line is laid. The cable lying in the tier should be opened by a “dripping loop” 30 – 40 cm long into the funnel of the drainage pipe. They also do when installing a system on a flat roof.
5. One or two threads are also launched into the drain pipe depending on its diameter. In the lower part of the drain pipe, the number of turns should be increased, since it is colder than the upper. On the roof, the cable is laid zigzag. The zigzag step is determined as follows: for a soft roof from the calculation of the necessary specific power (W/sq. m), for hard – in accordance with the pattern of the roofing.
6. If the funds for the purchase of a self -regulating cable in the right amount are not enough, it can only be applied in terms of the system. The most appropriate can be considered the use of such a cable for heating the drain, while the roofing part can be equipped with a cheap unregulated cable.
7. Next, choose the location of installation (connecting) boxes, so that they are available for maintenance. Most often they are placed on the roof next to the heating cable. This element can be fixed somewhere under a visor or on a fence (on a parapet). If there is an attic, you can place boxes there.
8. Determine the necessary shoulder and total power.

The approximate heating power for different roof components is:

• for ghost up to 150 mm wide: on the "cold" roof – 30 – 60 W/m, on "warm" – 100 W/m;
• For gutter with a width of more than 150 mm: 200 W/sq. m;
• On the roof (cornice overhang): on the "cold" roof – up to 150 W/sq. m, on "warm" – 200 – 250 W/sq. m;
• In yendov: 250 – 300 W/sq. m;
• On flat roofs around the drain trays located in the adjoining zone to the parapet: 40 – 80 W/sq. m.

A drainage system’s total shoulder-out power cannot exceed 17 W/m if it is constructed entirely of plastic components and has heating cables. The maximum permissible uninfected power for roofs with soft roofing is 20 W/m.

Next, figure out how long the heating cable is overall and how many chains there are, keeping in mind that a chain’s maximum length is between 120 and 150 meters (depending on the cable brand). An independent RCD should be used to connect each circuit.

Finally, the number of circuits and the amount of electricity they use are taken into consideration when designing the control panel.

Installation of a roof heating system

Installing a roof anti-icing system calls for specific power equipment operating knowledge and abilities. It is best to get in touch with experts if you lack voltage experience, or at the very least, invite a practitioner to their partners.

Tools and materials necessary for working with a roof anti -icing system

The installation will require the following tools:

• drill;
• riveting ticks;
• screwdriver;
• hammer;
• roulette;
• multimeter;
• Megomometer.

To perform tasks at this height, a staircase is required.

Certain materials, like GE GREY RTV 167 brands, might require specialized glue. It is utilized on pliable roofs where self-tapping screws or nails are not suitable for fastening a heating cable fixer.

Preparation of the cable for installation and connection

Installing an anti-icing system involves the following steps being taken in that order:

1. The cable is examined for damage, and if they are not found, they begin to assemble sections.
2. Start laying the cable. You can start with gutters of the drainage system. The manufacturer prescribes some types of cable to be laid directly in the gutter, in this case the mount is not required. If necessary, still fix the cable, use the clamps installed on the glue. If, according to the instructions, the cable needs to be laid outside the gutter, then it is fixed with a mounting tape, which in turn is fixed on the gutter with rivets. When installing the riveting, its itself and the hole must be treated with a sealant.

Depending on the type of cable, the mounting tape installation process is as follows:

• for resistive (unregulated) – 25 cm;
• for self -regulating – 50 cm.

Installing separators between adjacent cable lines—which should be spaced 25–30 centimeters apart—is essential to preventing cable tangling in the event of snowfall or strong winds.

To prevent harm to the cable, the following is prohibited:

• lay it on sharp edges;
• pull with effort;
• walk around the cable;
• squeeze or twist it;
• overlap.

Furious cable fastening on drains

The heating cable is installed on the drain pipes in a similar manner: either by climbing inside or by using mounting tape to secure it from the outside. Thermal tubes are a useful tool for attachment. To prevent the cable from breaking under the weight of the pipe, it must be installed on a metal cable with a polymer shell if the pipe is longer than 6 meters.

After creating a "dripping loop" in the cable funnel, the end of the cable needs to be secured with a screed before it can be laid in one thread. A bracket can be used for cable fixation in a funnel.

When laying multiple lines, a different bracket is used to attach each line.

Video: Installation of the heating system of drains

Cable installation on the roof

A perforated ribbon is used to secure the cable to the roof. This ribbon can be fastened with self-tapping screws or, in the case of soft roofs, glued with special glue. Sealant is applied to the screw during installation as well as to the roofing hole. Instead of removing extra sealant, apply a thin layer of metrite on it.

The mounting ribbon for the cable needs to be positioned 7.5 cm beneath the tile on the completed tile roof before being glued in place. This tape is nailed to a continuous crate if the tiles haven’t been laid yet.

Removing excess glue is also not necessary when using it. Speaking through the holes in the perforated tape and allowing it to dry, he functions as a self-tapping screw or nail to strengthen the mount.

The warm cable installation instructions include information on how to install mounting tape. 15 to 25 cm is the norm.

These days, a lot of producers include clip clip clamps, which require pliers to secure the cable, with the heating cable. Prior to that, the clamps need to be affixed to the roof using glue, self-tapping screws, or nails.

Use a different technique: the cable is clamped to the pre-laid grid.

1. Bring a cable in the valleys using the cable for additional fixation (in addition to the mounting tape). It is necessary to ensure the contact of the cables on the roof and in the gutter, so that there are no cold zones between them. Otherwise, water can freeze on the edge of the roof. For this, the cables are attracted to each other with screeds.
2. After laying the heating cable, the sensors of the weather station are installed. The temperature sensor is most correct to place in the gutter, the humidity sensor is in funnels and gutters or other places where the probability of icing is the greatest.
3. Next, mounting boxes are attached. So that water does not get into them, water discords should be fixed.
4. At the last stage, the readiness of the heating cable for work is checked. To do this, it is nicknamed, then the insulation resistance is determined.

Video: laying the cable of the snowball system on a multi -sized roof

The call of the heating cable

A megammeter is used to determine the cable’s insulation resistance.

The measurement needs to be done at a voltage of not just 500 and 1000 V, but also 2500 V for a thorough check; otherwise, some defects might not be covered.

Measure the resistance between the shielding metal braids and the conductive veins first. Measuring the resistance between the metal braid and the surface is necessary if the cable is installed on a metal one.

This is the order that the check is completed:

1. The system is disconnected from power.
2. The voltage on the megammeter is exposed to zero.
3. Both conductive veins alternately connect a positive electrode, and a negative to a metal braid is negative.
4. By turning on the metometer, set a voltage of 500 V and withstand it for a minute. After that, measure the resistance.
5. Similarly, resistance measurements at a voltage of 1 and 2.5 kV are made.
6. Turn off the metometer and discharge it through a grounded conductor (if the model is not self -discharge).
7. If the cable lies on a metal surface, measure the resistance between this surface and a metal braid. The same actions are performed, only a positive electrode is connected to the metal surface.

Generally, regardless of the voltage and circuit length, all three resistances should have a value of at least 1000 MOM. In this instance, one resistance—for instance, the resistance between a core and the screen—should be the same for all three voltages and shouldn’t vary by more than 25% amongst the resistances in the same circuit.

Measuring the resistance between conductive veins at both ends is required when using a self-regulating cable. Ohms should be three. A value greater than 100 Ohms denotes damage to the chain’s cores or a break in the connection between its sections. All components with heat-assigned materials, such as the final coupling, should be replaced following such a check.

Connection and commissioning of a roof anti -icing system

The required connections are made after the insulation resistance is examined:

1. Pay and connect the power cable, as well as control cables (signaling).
2. Collect and set the control cabinet for it intended for it.
3. Perform a check of strength and signal cables by calling and measuring insulation resistance.
4. Check the performance of the RCD. For this, a controlled current leak must be made, which is allowed only to specialists.
5. Tune the thermostat.
6. They begin to perform start -up work: they check how the warming cable works, if necessary, adjust the thermostat.

It is not possible to perform a complete check by simply pressing the Test button on the RCD case. The only way to ascertain the differential current at which the switch is triggered and how quickly it does so is by using controlled leakage.

Only during the winter can a thermostat be fine-tuned.

Upon completion of installation and in the owner’s possession, the following documentation ought to be kept:

• passports of the system of anti -icing, thermostat and control cabinet;
• certificates for all components of the system;
• Protocol with data on insulation resistance.

Preparing your roof and drainage systems for winter is essential to preserving the structural integrity of your house. In cold weather, anti-icing cable systems are essential for preventing ice dams and guaranteeing adequate drainage.

The installation of anti-icing cables requires careful planning and calculation. Effective performance is ensured by correctly sizing the cables according to the type of roof, the local climate, and any areas that are prone to ice buildup. Complete protection requires planning the layout to include vulnerable areas like gutters, valleys, and eaves.

Anti-icing cable installation requires meticulous preparation and execution. The proper installation of cables in gutters and along roof edges, along with their connection to a dependable power source, ensures their functionality. In addition to preventing damage from ice buildup, proper installation prolongs the life of your drainage systems and roof.

Just as crucial as the initial installation of your anti-icing cable system is its ongoing maintenance. Before winter arrives, routine inspections make sure the cables are in good shape and ready to work. The efficiency of cables is further increased by maintaining appropriate insulation around them and cleaning debris out of gutters. You can depend on your anti-icing cables season after season with preventive maintenance.

Video on the topic

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