Abstract: An electrical resistance heater element has a metal tube containing an electrical resistance coil that is electrically insulated from the metal tube by magnesium oxide powder, the coil being bonded to a conductor pin that protrudes from an open end of the tube. The powder is sealed against moisture by placing at least the open end of the tube within a chamber and immersing the open end within liquid silicone. A gas is pumped into the chamber to pressurize the silicone sufficiently to cause some of it to encroach into the powder through the open end of the tube. The heater element is installed within a heat exchanger with the silicone remaining uncured.

Abstract: An electrical heater bundle has heater elements, each including a metal tube, an electrical resistance coil within the tube, a conductor pin connected to the coil and protruding from an end of the tube, and an electrical insulation powder surrounding the coil within the tube. A conical cavity is located in the insulation powder at the end of the tube, the cavity extending from an inner diameter of the tube to the conductor pin. The cavity is filled with an epoxy that is cured in place. The insulation powder may have an infiltrated layer at the cavity that is an uncured liquid silicone. The heater elements are mounted to a header plate, and the elements associated with the three different phases of electrical power may protrude past the header plate at different distances.

Abstract: A circulation heater has a tank with heater tubes located within. The heater tubes are mounted to a header plate, and each contains an electrical resistance heater wire. A standoff plate is mounted to an exterior side of the header plate. Standoff tubes are secured to the standoff plate, each of the standoff tubes registering with one of the heater elements and containing an electrical conductor. A standoff housing is mounted to the opposite ends of the standoff tubes. The electrical conductors in the standoff tubes extend into the standoff housing for connection to electrical power wiring. Detaching the standoff plate from the header plate allows the standoff housing, standoff plate and standoff tubes to be removed as a unit from the tank.