Protect water pipes from freezing with the right heating cable. Heatline offers reliable solutions for homes and industry, including cables installed inside drinking water pipes or on the outside of pipes. This guide explains how to choose the correct cable, insulation and controls, and how to install the system safely and efficiently.
Important Rules for a Long-Lasting and Energy-Efficient System
Required heating cable output and thermal insulation: For water pipes, a heating cable with an output of up to 10 W/m is generally sufficient. After installing the heating cable—whether inside or outside the pipe—always cover the pipe with thermal insulation.
Without insulation, heat escapes into the surrounding environment, the system consumes excessive energy, and during severe frost the pipe may still not be adequately protected against freezing. The heat-loss table included in the image gallery will help you determine the required insulation thickness.
For example, if your water pipe is located outdoors and must remain frost-free at temperatures as low as −30 °C, a 3/4″ or 1″ water pipe requires at least 3 cm of additional thermal insulation.
Energy-efficient control: To ensure efficient and economical operation, we always recommend adding a thermostat. The thermostat switches the heating cable on only when the pipe temperature falls to a critical level—for example, +2 °C—and switches it off again when there is no longer a risk of freezing. This rule also applies to self-regulating heating cables.
If it is no longer possible to install a thermostat and temperature sensor on the pipework, we recommend using at least a smart plug. This allows you to create a timed operating schedule and optimise energy consumption.
Which technology should you choose? Should you use a self-regulating heating cable for a temporary solution, or choose a constant-wattage heating cable—such as Heatcom Aqua Safe—for long-term and more energy-efficient operation? Read more about the differences between these technologies in this blog post.
1. Installing a Heating Cable on the Outside of a Water Pipe
Installing a heating cable on the outside of the pipe is the easiest and most common solution for pipelines that are still under construction or for water pipes that are easily accessible.
How should it be installed correctly?
- Installation method: Attach the heating cable to the pipe in a straight line along its length. The best position is on the lower side of the pipe, at approximately the 4 o’clock or 8 o’clock position when viewing the pipe in cross-section. This allows the heat to rise evenly and protects the heating cable from possible mechanical damage if the pipe rests against another surface.
- Special considerations for plastic pipes: When installing a heating cable on a plastic pipe, first apply aluminium tape along the entire length of the pipe beneath the cable. This helps distribute the heat more quickly and evenly across the plastic surface and reduces the risk of localised overheating. This additional layer of tape is not required for metal pipes.
- Securing the cable: Always secure the water pipe heating cable along its entire length with aluminium tape—not just with short pieces of tape at intervals. Full-length taping provides maximum heat transfer from the cable to the pipe and prevents the cable from sinking into the thermal insulation.
- Installing the sensor: If you are using a thermostat, attach its temperature sensor to the part of the pipe where the risk of freezing is greatest. The sensors supplied with thermostats can generally be extended up to 50 metres. Attach the sensor to the surface of the pipe on the side opposite the heating cable so that it measures the temperature of the pipe rather than the temperature of the heating cable itself.
2. Installing a Heating Cable Inside a Water Pipe
Installing a water pipe heating cable directly inside the pipe is the most effective solution for existing pipelines or underground pipework where excavation and external insulation are no longer practical.
The internal frost-protection heating cable is inserted into the pipe through a pressure-tight cable gland installed on a tee fitting, as shown in the image gallery. The heating cable must enter the tee and pipe in a straight line or at the smallest possible angle.
Practical experience shows that in a 1″ pipe, a heating cable can generally be pushed in from the end of the pipe for approximately 20–25 metres. Special insertion tools may be required for longer pipelines.
When used with a thermostat, internal installation is approximately 20% more energy-efficient than installing the cable on the outside of the pipe because the cable is in direct contact with the water. This is particularly beneficial for longer pipe sections.
The connection between the heating cable and its power supply cable must always remain dry and outside the pipe.
What should you consider when installing a heating cable inside a pipe?
- Drinking water certification: If the cable is installed inside a drinking water pipe, it must have the appropriate certification. For example, it may have a special fluoropolymer outer jacket that does not release harmful substances or unwanted flavours into the water.
- Cable insertion: The heating cable is inserted into the pipe through a special pressure-tight cable gland. A tee fitting is installed in the pipeline, as shown in the illustrations, and the cable is pushed into the pipe through the tee. Make sure there are no sharp corners or edges inside the fitting.
- Avoiding obstructions: Never push the heating cable through shut-off valves, taps, or sharp 90-degree elbows.
- Determining the correct length: Measure the length of the pipeline as accurately as possible. A constant-wattage heating cable must never be shortened without proper guidance or forced into folds inside the pipe. Shortening may be possible in some cases, but always consult our technical support team beforehand. A self-regulating heating cable can be cut to the required length, but all connections and cable ends must be completely watertight.
Still need help choosing the right solution? Consult the heat-loss table provided with the products to determine the required thickness of additional thermal insulation, or feel free to contact the Heatline experts for advice.