Are you having issues that existed home heater occupies room space and could be a potential source of danger for the young baby?
Are you having issues that the water pipe bust due to freeze in cold winter?
Are you having issues that big ice dam and icicle on roof which may bring danger for people?
Are you having issues that car is prone to skidding when you are driving on Icey and snowy roads?
You are not alone. These problems are widespread in many parts of the world. Especially in some cold areas. Today we will introduce how to use heating cables and electric heat trace systems to avoid and solve these problems that are closely related to our life and production.
Part 1: Electric Heating Cable general information
Part 2: Typical Heat Tracing System Cables
Part 3: Typical Application of Heating Cables
Heating cable is key part of electric heat tracing system. It is very important for user, installer and related people to know some knowledge of heating cable.
Figure 1: RuiHao Icoheat self-regulating heating cable
This guide will bring you some knowledge about electric heating cable from different side. You will have good recognition on heating cable. It will be helpful for you to judge heating cable quality and how to find a reliable heating cable supplier.
Part 1: Electric Heating Cable general information
Heating Cable also named electric heating cable, heat tape or electric heat tracing. It has been widely used as an effective pipeline (storage tank) heat preservation and antifreeze solution.
Applying heat to pipeline carrying process fluid is a common requirement in many industries like oil, petroleum, plastics, chemicals etc. Such electric heat tracing systems is used to maintain the pipe line systems at or above a specified temperature.
Its working principle is to distribute a certain amount of heat from the heat tracing cable, and direct or indirect supplement the loss of the heat trace subject by heat exchange, so as to achieve the normal working requirements of heating, heat preservation or anti-freezing.
Although non-electrical steam heat tracing system can also be used for purpose of prevent the pipelines from freezing, to maintain fluid temperature and flow in a pipeline, electrical heat cable system is approved to most practical heat tracing system as it can make done for high thermal efficiency, precise temperature control, energy saving, simple construction, no pollution, convenient maintenance, low maintenance cost and long service life.
Electric trace heating concept begins early time of 20th century. But there is no dedicated equipment was available. In 1950s, Mineral-insulated heating cable was firstly introduced, as well as parallel constant wattage heating cable which can be cut to length. And 1971, self-regulating heating cable with core of conductive plastic was introduced to market. Similar time, the American energy industry put forward idea of replace steam tracing system to electric heating trace system. Time goes to 1980s, many industrial sectors including energy industry have widely promoted electric heat technology to replace steam system. Since the development of electric heating technology, it has developed from the traditional constant power heating cable to the self-limited heating cable.
Figure 2: typical electric heat tracing cable from RuiHao Icoheat
For nearly a century development, heating cable application are expanding to
- Pipe heat tracing system
- Pipe freeze protection
- Roof, gutter, and downspout de-icing system
- Outdoor snow melting/ ice protection
- Electric floor heating and warming system
- Door/frame interface freeze protection
- Soil warming
- Window de-misting
Part 2: Typical Heat Tracing System Cables
2.1 What is Self-regulating heating cables?
Self-regulating heating cables, also named self-limited heating cable. It is used for applications that require a heat output that varies with changes in the temperature of the air or other medium surrounding the heating cable. A self-regulating cable automatically varies its output power according to ambient temperature change. It increases its heat output while the ambient temperature is decreasing. Relatively, it decreases its heat output while the ambient temperature is increasing.
Due to its characterizes cut to length, heat rapid, no high temperature hot spots when multiple overlapping, self-regulating heating cable become main cable used in electric heat trace system. It is mainly used for pipeline freeze protection and temperature maintenance on metal and plastic pipes among residential, commercial, and industrial area.
2.1.1 What is Self-regulating heat cable construction?
Here picture show typical self-limited heat tracing cable structure.
Figure 3: Self-regulating cable structure
① Copper bus wire
② Self-regulating conductive polymer heating element
③ Inner insulation
④ Earth braid
⑤ Outer sheath
Self-regulating heating cable use two parallel bus wires to carry electricity. Two bus wires are encased in a polymeric self-regulating conductive core heating element. Then Insulated entire part with thermoplastic or fluoropolymer jacket to protect from electricity leakage, use tinned copper braid as ground protection and extra outer sheath to protect cable work well under different weather or corrosive environment.
2.1.2 How does self-regulating heating cable work?
It is often asked What is self-regulating heat cable work principle. Electric heating elements of self-regulating heating cable is matrix made of a semiconductor PTC(Positive temperature coefficient) material extruded even between two parallel copper bus wires. Self-regulating cable produce heat from the flow of current through PTC material and innumerable electrical paths generated in matrix change in response to temperature variations.
When copper bus-wires at the one end of cable are connected to the power supply (the other end should be sealed), the current flows laterally from one bus-wire to the other bus wire through PTC matrix. PTC matrix convert electrical energy into heat as it is resistance heating element. While ambient temperature is cold around heater cable, Polymer in PTC self-conductive core contract. This decreases the electrical resistance and creates numerous parallel resistance electrical paths between the bus wires. As a result, more current flows produce more heat which appears as high output power. With heating cable get warm, polymer distance in PTC matrix expands, it increases the electrical resistance and decrease parallel resistance electrical paths between the bus wires. As a result, less current flows reduce heat which appears as low output power. When ambient temperature goes up its melt point, extremely high resistance makes outpower reduce to very small even zero to protect cable itself.
Irradiation is necessary for a self-regulating cable. After radiation cross-linking, the molecules of the self-regulating heating cable are tighter, and the PTC characteristic of the self-regulating heating cable is improved. It will helpful to improve self-limited cable ability of anti-aging, anti-high temperature, and its work performance and service life.
Figure 4: How self-conductive heating element works
2.1.3 What is Self-regulating heating cable advantage?
Different with constant wattage heating cable, self-regulating heating cable has following advantage:
- Safe:
Self-regulating cable adjust its output power in response to ambient temperature. Multiple overlap is allowed and no overheat accumulation when overlap.
- Easy installation:
Self-regulating cable can be cut to length which mean it can be cut arbitrarily on site or used by connecting pieces within the specified length range; Start up quickly in low temperature status and temperature of each section is evenly, easy to use.
- Energy-saving:
The characteristic of automatically adjusting its wattage according to surrounding temperature can make heat trace cable realize the effective use of electric energy, improve efficiency of operation and save operation cost.
- Precise temperature control:
Can realize precise temperature control even without additional temperature controller.
- Reliable, low maintenance cost, and no pollution for environment.
2.1.4 Is there any difference between Self-regulating heating cable types?
Self-limited heating cable can be classified into different range according to temperature and supply voltage.
Self-regulating Heating cable can be classified as low temperature heating cable, medium temperature heating cable, high temperature heating cable, and supper high temperature heating cable. The main difference is result from different composition of heat matrix. Low temperature Self-regulating cable
Figure 6: self-regulating heating cable temperature range.
As well as self-regulating heating cable are designed to suit different supply voltage.
Low voltage heating cable: Supply voltage is 12-36V. Such cable generally has a low heating power and use length does not exceed 10Meters.
Medium voltage heating cable: Supply voltage is 100-660V. It is most used heating cable we refer to.
High voltage heating cable: Supply voltage exceed 380V. They are mainly the aforementioned 5-6 core heating cable. Such heating cable continuous application length is longer than 500 meters.
2.2 What is Parallel Constant Wattage Heating Cable?
Different from wattage of self-regulating heating cable affected by varying ambient or pipe/tank media temperature, medium Parallel constant wattage heating cable is a heating cable that has same output throughout its entire length. The power output of constant wattage electric heat tracing cable is always constant after being energized and will not be changed with changes of external environment, thermal insulation material and media heated. A temperature controller is necessary to be used to control its power output or stop. They are widely used for process temperature maintenance, anti-freezing, anti-condensation, heat of metal pipes, valves and storage equipment which require a high-power output and or high exposure temperature in petroleum, chemical, electric power and metallurgy.
2.2.1 What is constant wattage heating cable structure?
Figure 7: Ruihao parallel constant wattage heat cable
① Copper bus wire
② Conductor insulation
③ Heating conductor
④ Supported insulation
⑤ 2nd insulation
⑤Tinned copper protective braid
⑤Outer jacket
Parallel constant wattage heating cable consists of a coiled resistor alloy-heating element wrapped around two parallel bus wires. It is connected alternately between the two-copper bus wire at fixed distance along cable itself. Jiont location between heating wire and copper bus wire is named contact point as well as node connection. Distance of conjoint contact point is fixed and normal is 1 meter. Then cable is protected by 2nd insulation, earth braid and outer jacket. Outer sheath normal is rubber or fluoropolymer.
2.2.2 What is constant wattage heat cable work principle?
Alloy-heating element wrapped around bus wires is carrier to produce heat. When copper bus-wires at the one end of cable are connected to the power supply (the other end should be sealed), the current flows reach to resistance wire to generate heat. Different there are numerous electrical paths for self-regulating cable, The distance between two node connection forms a heating zone. For this reason, parallel constant wattage heating cable are named zoned heating cables.
2.2.3 What is constant wattage heating cable features & advantage?
Constant wattage heating cable has following advantage:
① Longer use length
Its application length is longer than self-regulating heating cable. It can reach to 600M in two-way use.
② Heat evenly
Every part of heating cable has same wattage and stable heat.
③ No startup current, long service life
④ Different material used can withstand different range temperature. Max to 250°C if high level fluoropolymer is used.
⑤ Benefit from many zoned heaters existed along heating cable is that parallel constant wattage heat trace system will continue to operate even one or two zone heater is failed.
Meantime we also need put attention on installation and maintenance of such zoned heating cable.
① Make sure not overlap or touch cable itself as it will be subject to overheating or burnout.
② Make sure that temperature controller always in good work status. The electric heating system applied with constant wattage heating cable will always continuous to heat once controller is failed. Think about consequences it can not be stopped.
③Wrapped heating wire will be easy to age if parallel heating cable is energized for a long time.
2.2.3 What materials are used for constant wattage heat cable?
Material used for constant wattage heating cable most depend on wattage designed, application environment, exposure temperature etc. typical material for example Silicone, Polyethylene, fluoropolymer are used.
Figure 9: Ruihao Icoheat silicone parallel constant wattage heating cable
2.3 What is Series resistance heating cable?
Series resistance heating cable is other type constant wattage heating cable. For this reason, it is also named series constant wattage heating cable. Power output of both series heating cable and parallel heating cable are fixed under certain voltage, will not be varied with ambient temperature.
Series heating cable is commonly to be used in industrial application such as when transporting fluids between different processing sates in petrochemical facilities or to storage, especial for some long pipeline heat tracing application when circuit length exceeds the usage length self-regulating heating cable can reach. Meantime series resistance heating cable are also widely used in commercial and residential application such as electric underfloor heating for house, roof gutter de-icing for building, ramp heating or snow melting for walkway, as well as soil warming for greenhouse.
Figure 10: Ruihao Icoheat Series heating cable
2.3.1 Typical structure of series resistance heating cable
Figure 11： Typical series heating cable structure for underfloor heating mat
Figure 12: Series heating cable for industrial longline heat tracing
① Heating conductor
② Dielectric insulation
③ Earth conductor (braid or drain wire wrapped by Alu-foil)
④ Over jacket
The resistive heating cable is made of a cable structure, which uses electricity as an energy source and uses alloy resistance wires to conduct electricity and heat to achieve the effect of heating or temperature maintenance. It starts with a high resistance wire (usual alloying element), then electrically insulated and protected by high temperature, heavy-wall fluoropolymer insulation, a metal grounding braid or drain wire shielding with Alu-foil, and an out sheath.
There are single conductor and double conductor heating cable.
2.2.2 Series resistance heating cable work principle
Different from self-regulating heating cable generate heat by PTC matrix, the resistance wire of conductor produces heat. When series heating cable are connected to the power supply (the other end should be connected), heating wire convert electricity into heat. A series heating cable is a close a circuit and a circuit can not be cut. It is powered at a specific voltage and cable wattage depends on voltage supplied and circuit length.
Figure 13: Series heating cable
2.3.3 What is constant wattage heating cable features & advantage?
Series heating cables are most easy cable in electric heating cable series. It is Easy constructed which mean you design and create different type heating cable with different material to suit for different application. Light heating cable is used for indoor underfloor heating. M2 range heating cable is used for outdoor heating. And fluoropolymer jacket provides high exposure temperature.
Series heating cable is ideally used for longline pipe heat trace, especial pipe lengths beyond the maximum circuit lengths of parallel heating cables
It is with constant power output, and have zero starting current and no voltage drop no matter how long heating cable is. So, it is easy to monitor heating cable current.
Downside of these type cable is that they cannot overlap on themselves they can overheat or burnout.
And they are provided in specific length and can not be shortened unless you are master professional. And One series heating cable is a circuit. So, a break anywhere along the heating cable will result in a failure of entire cable.
Good side is that series heating cable is not expensive as self-regulating cable and parallel heating cable.
Part 3: Typical Application of Heating Cables
Nearly a century, heating cable are widely used in many residential, commercial and industrial area to help people to solve different heat supply problem.
3.1 Electric underfloor heating system
Floor heating system also called radiant floor heating system, are used to heat or warm a floor by radiant heat generated by heating elements to cooler air in the room. Compared to traditional heat equipment radiator, electric underfloor heating has little dispersed through convection which mean you can save some cost. And underfloor heating system is really comfortable heat solution which make floor warmer than the rest of room as people feel much better once feet are warmer than rest of body. You will never get such comfort from radiator or air conditioning which may bring overheat in air for your head.
Electric heating floor system are commonly used as either main or supplementary heating to heat different type floor include but not limit tile, stone, wooden, carpet, laminate. Typical electric floor heating system products include underfloor heating mat, floor heating cable, Alu-foil heating mat, uncoupling membrane heating system. Insulation board is suggested to use to heat quick and reduce heat lost.
Figure 14: loose floor heating cable
Figure 15: underfloor heating mat
3.2 Roof & gutter de-icing system
Heating cable applied in roof gutter heating system is to prevent ice dams and icicles from forming on roofs and in gutters and downspouts. In cold winter, snow and ice are easily accumulated in roof gutter and downspouts which block proper operation of drainage system. It means melted snow and ice cannot discharge to ground and be stopped on roof by ice dam which often cause leakage into building. As well as icicles, formed from dripped off cold water, can cause severe injury on people when they break away from roof and gutters at good weather.
Roof heating cable system is good choice to stop this happen. It melts snow and ice around it. Instead of melt all ice and snow, it creates a continuous channel through which water can drain to safe discharge area instead of trapped in roof and gutter. As well as it is typical installed in roof edge to stop form icicles. Typical Roof heating cable include Self-regulating heating cable, specifically designed series heating cable.
Figure 16: roof heating cable installation
Figure 17: Ruihao Icoheat pre-assembled self-regulating heating cable for roof de-icing system
3.3 Outdoor snow melting
Each year thousands of people are injured from fall related with snow and ice.Outdoor snow melting system, named as anti-icing systems, are used to prevent snow & ice buildup, to dry and make non-slippery on concrete or asphalt surface in winter. Typical used in driveway, walkways, stairs, building entrance, pavements, footbridges, ramp, car parks, and ground below cold-store rooms.
The heating cable should be constructed to withstand harsh conditions to make it suitable for outdoor heating usage. The cable should be strong enough, durability and with anti-high temperature outer jacket if encased in high temperature asphalt. Specifically designed series heating cable are used more and more in electric snow melt because of cheap price, long service time. Beside snow melting cable need to be looped by installer on site, snow heating mat are much easier to lay down.
Figure 18：Walkway heated by snow melting system
Figure 19: Ramp heating cable
3.4 Frost protection
A physical fundamental principal sates that heat energy goes from warm zones to cold zones. Every pipe or vessel is subject to heat loss when its temperature is greater than ambient temperature. If the heat loss is large enough, there is a risk that liquid in the pipes will freeze and may burst pipe. To protect water pipe from freeze in cold weather, apply water pipe heating cable on pipe is easy and effective method. A thin self-regulating heating cable and pre-assembled water pipe heating cable with thermostats are suggested to be used.
Figure 20：Pipe Freeze protection
Figure 21: Pipe defrost cable
3.5 Industrial Heat trace
Electric heat tracing is mainly designed for freeze protection and process temperature maintenance purpose. In cold climates, thermal insulation is not enough to prevent pipe from freezing result from heat loss. As well as industrial pipe need to be heated trace to compensate heat to maintenance liquid at certain temperature. A power distribution system, electric heating cable and components, control system are necessary for a heat tracing system
Besides application we introduced, heating cable are also used in greenhouse, cold room, farm, vineyard, oil refineries, nuclear power plants, logistics storage. We will introduce it soon.
OK, hope it will make sense for you to understand heating cable.