Abstract: A spa or hot tub system includes a tub forming a cavity that holds a fluid such as water therein, and a water circulation system provides for circulation of water within the tub. The hot tub includes inner and outer surfaces, and defines an internal space. A heat pump system is operably connected to the water circulation system, and heats the water in the hot tub. The water side heat exchangers of the heat pump may include a polymer housing, and coiled inner elements for refrigerant. The coils may be made of a corrosion-resistant metal tubing or the like. The system may include a conventional electric heating element in addition to the heat pump to provide additional heating capacity.

Abstract: A method of making a titanium heating element for electric water heaters includes heating commercially pure titanium tubing to a specified temperature for a predetermined period of time. A resistance wire and magnesium dioxide powder may be positioned in the tubing prior to the annealing process. The outer surfaces of the titanium tube are exposed to the air during at least a portion of the annealing process, such that a layer of titanium dioxide develops on the outer surface of the titanium. The heating element is then formed into a loop or other suitable shape, and it is positioned inside a housing. The housing may include fittings to connect the water heater to the tubing of a pool, jetted tub, spa, hot tub or the like.

Abstract: A spa or hot tub system includes a tub forming a cavity that holds a fluid such as water therein, and a water circulation system provides for circulation of water within the tub. The hot tub includes inner and outer surfaces, and defines an internal space. A heat pump system is operably connected to the water circulation system, and heats the water in the hot tub. The water side heat exchangers of the heat pump may include a polymer housing, and coiled inner elements for refrigerant. The coils may be made of a corrosion-resistant metal tubing or the like. The system may include a conventional electric heating element in addition to the heat pump to provide additional heating capacity.

Abstract: An electrical heater for fluid including a generally tubular housing have a wall portion made of a titanium material, and an elongated electrical heating element having electrical connectors on opposite ends thereof extending through the wall portion. The electrical heating element has an outer sheath made of a titanium material, and an inner sheath made of a stainless steel material. The electrical heating element has an electrical resistance line disposed within the inner sheath and connected to the electrical connectors at opposite ends thereof. The electrical heating element includes a dielectric material disposed within the inner sheath around the electrical resistance line to facilitate heat transfer from the electrical resistance line to the inner sheath.

Abstract: A heater for fluids includes a housing made of a non-metallic material and having an internal cavity. The housing has an inlet and an outlet, each of which are in fluid communication with the internal cavity. An elongated electrical heating element is disposed within the cavity for heating fluid flowing through the cavity. The heating element has a generally circular cross-sectional shape and has a U-shaped portion disposed in the cavity. The electrical heating element has electrical connectors at opposite ends extending through the housing, and a titanium outer surface.

Abstract: A heater is provided with an accurate shutoff device that shuts off (de-energized) the heater upon detecting an over temperature condition. The heater includes a body for holding material (water) to be heated and a first heating element coupled to the body for heating material within the body. The heater also includes a temperature sensitive element coupled to the body for sensing temperature, and a shutoff switch coupled to the temperature sensitive element for shutting off the first heating element when the temperature sensitive element senses a temperature limit. The heater further includes a second heating element for heating the temperature sensitive element upon activation of the switch such that the first heating element is actively forced to remain shut off.

Abstract: A heater for fluids including a housing made of a non-metallic material and having an internal cavity. The housing has an inlet and an outlet, each of which are in fluid communication with the internal cavity. An elongated electrical heating element is disposed within the cavity for heating fluid flowing through the cavity. The heating element has a generally circular cross-sectional shape and has a U-shaped portion disposed in the cavity. The electrical heating element has electrical connectors at opposite ends extending through the housing. The electrical heating element has a titanium outer surface.

Abstract: An electrical heater for fluid including a generally tubular housing have a wall portion made of a titanium material, and an elongated electrical heating element having electrical connectors on opposite ends thereof extending through the wall portion. The electrical heating element has an outer sheath made of a titanium material, and an inner sheath made of a stainless steel material. The electrical heating element has an electrical resistance line disposed within the inner sheath and connected to the electrical connectors at opposite ends thereof. The electrical heating element includes a dielectric material disposed within the inner sheath around the electrical resistance line to facilitate heat transfer from the electrical resistance line to the inner sheath.

Abstract: A spa system includes a tub, a pump, an electrical heater, and a tubing system interconnecting the tub, pump, and electric heater to provide recirculating flow of water through the spa system. The electrical heater includes a housing made of a polymer material and defining an internal passageway adapted for fluid flow through the housing. The housing has a first opening in fluid communication with the passageway, and a pair of access openings. The housing further includes a second opening in fluid communication with the tubing system. The heater also includes a heater tube defining a first end connected to the first opening in the housing. An elongated electrical heating element is at least partly disposed within the outer tube, and has opposite ends extending out of the first end of the heater tube and through the pair of access openings. The electrical heater includes compressions fittings sealingly connecting the heater tube and the elongated heating element to the housing.

Abstract: An electric water heater is provided which includes a polymeric body having an elongated hollow and an inlet opening and an outlet opening in communication with the hollow for flowing water to pass therethrough. An electrical resistance heater having a heating element of a material exhibiting a positive temperature coefficient of resistance is disposed in the hollow of the polymeric body and in heat transfer communication with water flowing through the hollow. An electrical source supplies electrical power to the heating element to generate heat. A controller senses current flow through the heating element and determines a resistance related value, such as current or resistance of the heating element. The controller also determines a first derivative of the resistance related value over time, and determines a second derivative of the resistance related value over time, and controls power supply to the heating element as a function of the first and second derivatives and/or absolute resistance.

Abstract: An open coil electric heater wherein the resistance conductor is supported on a frame. The resistance conductor in this instance, instead of being in the form of a single coiled wire, is composed of a plurality of strands of wire so as to reduce the cost of the resistance conductor while providing adequate surface area. The strands of fine wire or flat ribbon wire are braided into a rope which is formed into a series of reaches in customary manner. At least one of the strands is of a material which will provide strength to the wires that primarily generate the heat and thereby prevent sagging of such wires between wire supports. In a preferred form, the wires are loosely braided to form wide open spaces and insulated support members are projected through certain of the open spaces to support the strands in predetermined position.