A nonadjustable thermostat turns these heaters on when the temperature drops below 38° F and turns them off when the temperature reaches 45° F. Often used to maintain liquid temperature and viscosity and provide freeze protection in pipe and tube systems, they supply the same wattage regardless of the surrounding temperature and are less prone to power surges than self-regulating heaters. To prevent burnout, they should be installed straight along pipes and tubes; they must not be overlapped or spiraled and must be in full contact with the surface being heated. All are rated for outdoor use. The plastic cable cover provides corrosion resistance and durability. Heaters have a plug with an indicator light that shows when the system has power.

Note: Only install these heaters in accessible locations; do not install them behind walls, underground, or in other difficult-to-access areas. Use fiberglass tape or heat-transfer putty to install them directly on surfaces that are free of dirt, grease, and rough edges. Do not use electrical tape, duct tape, metal bands, or wire. To prevent heat loss and protect heaters from moisture and corrosion, wrap them with fiberglass insulation.