Plastic-pipe restrictions for the constant-wattage freeze-protection cable covered by the linked manual.
The constant-wattage pipe-heating cable must not be installed on plastic pipe unless the pipe is filled with water at all times. The manual calls for plastic piping, including PEX, suitable for residential water applications.
A drain that is empty or only intermittently filled does not meet this condition.
Keep the heating cable straight along the pipe; do not spiral it. The manual recommends wrapping plastic pipe in aluminum foil before fitting the cable for more even heat distribution. Follow the complete instructions for securing the cable, insulation, thermostat placement, and electrical protection.
This restriction and method are for the constant-wattage product described in the linked manual. Do not apply them as a substitute for the instructions supplied with self-regulating heat trace.
Built-in thermostat and insulation
The built-in thermostat and the entire heating cable must contact the pipe. Place the thermostat tightly against the coldest end of the pipe and secure it with good-quality electrical tape.
Insulation applied over the heating cable must also cover the thermostat. Protect the insulation with a waterproof overwrap as instructed in the manual. Do not leave this built-in thermostat exposed to ambient air.
This is the built-in thermostat of the constant-wattage pipe cable described in publication 7680. For a separate PT-SINGLE or PT-DUAL probe, use the pipe temperature-sensor placement article and that controller’s instructions.
Sources
- Manufacturer instructions (publication 7680), PDF pp. 5–6.
