Heating of water pipes and sewage systems: methods and tools

24-05-2018
Pipes

In what cases is the electric heating of water pipes and sewage used? What heating elements can I use? How to mount them correctly?

Let's try to answer these questions.

Is open water supply compatible with the harsh Russian climate? The answer is not as straightforward as it seems.

When heating is needed

Actually, the answer to this question is quite predictable: forced heating is needed where pipes can be cooled below freezing point during operation.

Why can this happen?

  • Heating of water pipes and sewage willy-nilly must be ensured where it is not possible to lay them below the freezing level.. A typical example is permafrost: in the northern regions of a country, the ground often freezes through 3-5 meters and does not thaw over the summer.
  • Warm climate, paradoxically, also makes install heated. Warm winters with extremely rare frosts in some cases make the buried or hidden laying of communications simply impractical. So, the sewage system and water in the attic above the capital structure is much easier to stretch along the facade without spoiling the interior decoration of the house.
In the photo - a building in London. During the reconstruction, the sewage system was laid on the facade.

By the way: the temperature drop to 3-5 degrees of frost does not lead to freezing of water in the pipes. As the author repeatedly convinced, the problems begin with the night frosts reaching about a 10-degree mark. The reasons are the high salinity of tap water, the shift of the freezing point, and the warm evaporation of sewage.

Instruments

What could be the heater pipe water and sewage?

Resistive cable

The simplest solution is the so-called resistive cable, an insulated conductor with constant resistivity. With the passage of current, it will release the thermal power, exactly equal to the consumed electric power.

That, in turn, is calculated as the product of voltage and amperage; the current is equal to the result of dividing the voltage by the total electrical resistance of the conductor.

Obviously, by adjusting the length of the heating element with a known resistivity, it is easy to achieve the allocation of the necessary thermal power for each running meter.

The resistive cable can be either single-core, involving the laying of a closed loop, and strong, requiring the installation of a ring coupling.

Single and strong resistive cables.

The main and, perhaps, the only merit of the solution is its low price. The main drawback is the minimum flexibility in the choice of configuration: the buyer is forced to use a heating element of a strictly defined length.

Self-regulating cable

This problem is very ingeniously solved in the construction of a self-regulating cable, with a cross section more resembling a ribbon.

How is a heater tape for water pipes and sewers?

  • Two copper conductors running along the entire cable are connected to the zero and phase contacts.
  • Between them there is a conductive matrix, which is, quite simply, a mixture of plastic with a high coefficient of thermal expansion and coal dust.
  • Outside there may be a grounded braid, shielding the electromagnetic field during the spiral laying of the heater.
Scheme of the cable.

How does this scheme work?

  • When powering the conductive matrix due to the passage of current begins to heat up.
  • Where heating is not compensated by an intense heat sink, the expansion of the matrix causes a sharp increase in its electrical resistance: the conductor particles are removed from each other. As a result, the more heated the cable section, the. weaker it is heated.
Principle of operation.

What is good?

  • This cable is economical. In warm weather, it dramatically reduces power consumption.
  • He is not afraid of overlaps and the local overheating caused by them.
  • Finally, the length of the conductor can be absolutely any - if only the power consumption does not exceed the carrying capacity of the current-carrying veins.

Nuance: for any length, the cable must be equipped with a terminal sleeve - a carefully insulated jumper. The insulation consists of several heat shrinkable tubes, under which a small amount of silicone sealant is applied before shrinkage.

In addition, the second end of the cable is supplied with a current-carrying wire and an electrical plug; in the presence of braid, the plug must have ground contacts.

Ready section.

How to choose the optimal power of self-regulating cable?

Power density, watts per meter Application area
10 - 16 Heating water pipes with a diameter of up to 32 mm
24 Heated sewer diameter 50 mm
30 - 40 Heated sewer diameter 110 mm

Installation

Is it difficult to organize with your own hands the electrical heating of water supply and sewage pipes?

Outside the pipe

The simplest installation manual comes down to laying the heating element along the pipe in a heat insulating shell. The cable can be laid longitudinally or coiled.

For fixing the cable is recommended to use aluminum tape. The recommendation is connected with the fact that its reflecting surface helps to reduce heat loss due to infrared radiation.

However: on pipe bends it is better to use polyethylene clamps. Self-regulating cable is quite elastic and when you try to wind it to the pipe, it simply tears the scotch tape.

Exterior styling is simple, but implies large, untargeted heat loss. Even in the foam shell, a substantial part of the power consumption will be uselessly dissipated in space.

Exterior styling.

Inside the pipe

Heating the plumbing inside the pipe is much more efficient, but it requires solving the problem of sealing the cable entry point. For this purpose, special fittings with rubber or silicone seals are used: when tightening the union nut, the seal seals the cable tightly.

Sealing coupling.

Is it possible to lay the heating cable in the sewer pipe or septic tank?

Normally, this is strongly discouraged. However, here you need to understand one subtlety.

The outer sheath of any heating cable is polyvinyl chloride, the very plastic that is resistant to aggressive media, from which sewage pipes are made. But the heat shrinkage is much less resistant to aggressive wastewater and for a couple of years simply dissolves in them.

From here - an obvious conclusion: it is possible to warm from the inside and the sewerage; however, cable sleeves must be taken outside of it in any way. In addition, do not forget about the possibility of blockages: when cleaning the cable or wire can damage the cable.

Conclusion

On which of the heating methods to stop - the reader, of course, will have to choose on their own. All the necessary information is at his disposal.

As usual, a number of additional materials will offer a video in this article. Successes!