Gutter and Roof Heating Cable 30W/m Heatcom

The gutter heating cable is a UV-resistant constant-wattage heating cable specially designed for use on roofs and in gutters. It is significantly more affordable and reliable than a self-regulating heating cable intended for the same purpose.

The biggest advantage of a self-regulating heating cable is that it can be cut to exact lengths, making it the preferred solution in areas where there is a risk of gutter blockage due to leaves and pine needles. Self-regulating gutter heaters are not prone to overheating and, additionally, they do not require gutter clips or chain clips, which often cause leaves to accumulate and create blockages. If necessary, please call us for more information.

Gutter Heating Cable Installation Guide

A special constant-wattage, UV-resistant gutter and rainwater heating cable keeps gutters, pipes, valleys, and roof edges free of ice and snow while safely draining away the meltwater.

Whether heating cables should be installed at all, and how much power is needed, is highly individual for each house. The installation of a heating cable depends on how cold it gets outside while snow continues to melt on the roof. The lower the sub-zero temperatures (indicating poorer roof heat retention), the more heating cable power per square meter must be calculated or installed in the gutter.

Standard Gutter Installation: For a standard 12cm wide metal gutter or rainwater pipe, a 30W/m heating cable is used. It is sufficient to install one meter of heating cable per meter of gutter. In extreme cases, if ice and snow melt on the roof even at temperatures below -20°C, two strands of heating cable should be installed in the gutter.

Heat-Sensitive Surfaces: If a constant-resistance roof melting cable is installed on a bitumen roof, plastic gutter, or other heat-sensitive or flammable material, only a 20W/m heating cable is suitable. In this case, two strands of heating cable must be installed per meter of gutter to ensure the necessary heating power. When installing two heating cable strands in a gutter, spacer clips must be used every 25cm to prevent the cables from touching each other.

Downpipes: A heating cable installed in a downpipe must always reach all the way down to the mouth of the pipe. It is highly recommended to create a small loop at the mouth, as this is the most critical point for freezing. When the heating cable warms up, a "chimney effect" is created in the pipe, causing an intensive draft of cold air from the bottom, which can easily cause the pipe's mouth to freeze shut. For buildings where there is a risk of vandalism to the downpipes, the heating cable at the pipe's mouth should be placed inside a protective metal conduit, which is then secured to the downpipe with metal clips.

Planning the Installation: When choosing a gutter heating cable, evaluate the site through the eyes of an installer:

• How long of a section can realistically and conveniently be covered with a single heating cable? (An electrician cannot cover different gutter lengths across various roof planes with one continuous cable).

• Where are the available electrical supply points for the heating cable, or can new ones be added?

• Do we have sufficient electrical capacity to execute the project?

• Would it be reasonable to group the melting cables and distribute them across different power supply phases?

• Can all heating cables be routed to a single thermostat, or would it be more convenient to divide the house into north and south zones controlled by separate thermostats?

For larger projects, we strongly recommend utilizing a design firm to conduct a thorough site assessment and provide the best custom solution.

Roof Edges and Valleys

Roof valleys typically accumulate more snow and meltwater than other areas. Heating cables are calculated based on the square meters of the roof area to be covered, ranging from a minimum of 200W/m² up to 350W/m².

• If melting occurs on the roof down to -5°C, 200–250W/m² is sufficient.

• If melting occurs down to -15°C, an installed power of 250–300W/m² is required.

• If melting occurs down to -25°C, 300–350W/m² is required.

• If melting occurs down to -35°C, 350–400W/m² is required.

The width of the area that the roof edge heating cable should cover is also site-specific. At a minimum, it should be 50cm. To protect the cable-covered area, a snow guard must be installed on the roof. Without a snow guard, there is a severe risk that sliding masses of snow will damage or completely rip off the heating cables.

How to Fasten the Heating Cable to the Roof?

This is always a major challenge and a creative process.

• Standing Seam Metal Roofs: Making holes is generally strictly prohibited, but the cables still need to be secured. Glueable fastening clips or tapes are used, adhered to the roof with weatherproof glue. This is labor-intensive and time-consuming, but often the only option. If water drainage only needs to be ensured behind an upturned seam, the heating cable can be loosely attached to a heavy hot-dip galvanized chain, which holds the cable in place using its own weight.

• Tile Roofs: Specific mechanical fasteners are available for tile roofs.

• Profiled Metal Roofs: Fasteners are available and can be securely attached using screws.

• Bitumen/SBS Roofs: Fastening tapes, strips, or clips are attached using hot bitumen or weatherproof glue. Ask for recommendations if needed, as not all UV-resistant silicones are suitable for SBS roofs!

In roof valleys and on roof edges, the roof heating is installed in loops from top to bottom. If the roof edges lack gutters for draining meltwater, gutters should definitely be installed—meltwater directed over the roof edge can still create a dangerous icicle hazard!

A Final Reminder on Snow Guards: It is crucial to emphasize that snow guards must not be forgotten. If snow breaks loose and slides off the roof, it not only poses a threat to pedestrians or parked cars below, but it will also strip the roof of its newly installed heating cables.

Thermostats: For the gutter heating cables to operate efficiently, unnoticeably, and at exactly the right time, we recommend using a dedicated gutter heating control thermostat, such as the OJ ETR 1447A, or the OJ ETR 2 which includes moisture sensors.

See the illustrative picture gallery below for ideas on how to attach the heating cable to your gutter or roof.