Types of Surface Heating Units

Commonly used trace heating units may be divided into four distinct product classifications:-

• Series Circuit Heating Tapes and Cables (Constant Power Output)
• Parallel Circuit Heating Cables (Constant Power)
• Self -Regulating Heating Cables (Power Variable with temperature)
• Mineral Insulated Heating Cables

In addition to which a variety of other surface heating methods are available including
Resistance Technology manufactured Industrial Heating Fibreglass Blankets and Silicone Heating Pads, Mats and Drum Heaters.


Series Circuit Heating Tapes are supplied in predetermined, factory-terminated lengths and have a constant power output at rated voltage when energised. Available in a very wide range of lengths and power output ratings, they have provided many years of well-proven service . Glass covered element tapes such RPA tapes manufactured by resistance Technology Ltd can be used at high temperatures. They are available with optional metal wire braid outer cover for increased mechanical /electrical protection. The highly flexible construction of series circuit heating tapes, coupled with factory-made terminations, provide for easy and rapid installation. Series tapes are recommended where the lengths of the heating circuit is known.


Parallel Circuit Heating Cables are usually available in a number of constant power watts per metre options normally, but not limited, up to 40w/m. They may be cut to any convenient length and are therefore particularly suitable for poorly defined pipework systems or for maintenance purposes. Electrical terminations are normally completed on site where care must be taken to use those kits recommended by the supplier.


Self Regulating Cables give variable power output and can be cut to any convenient length. In certain applications control by thermostat is not needed but it is incorrect to assume that the output will fall to zero when the desired pipe operating temperature is reached, as the cable will continue to produce power at reducing rates as the ambient temperature rises above the minimum system design temperature. This type of cable is particularly suitable for the frost protection of water pipework and hazardous area applications where approved cables can give guarantees not to exceed the hazardous area temperature.

Mineral Insulated Heating Cables are semi-rigid, metal sheathed cables frequently used for very high temperatures up to 800 °C. The preparation and connection of terminations to mineral insulated heating cables requires a specialist technique and some skill on part of the operator to ensure moisture ingress is prevented.