Electric Resistance Heaters
Electric resistance heaters use electric currents to create heat. Because electric resistance heaters consume large amounts of electricity, they are primarily used to heat spas and small therapy pools and are rarely used to heat swimming pools.
An electric resistance heater creates heat by applying an electrical current to a metal resistor, which acts as a heating element. The metal resistor extends throughout assembly housing inside the unit. The metal resistor heats when a current is applied to it. The spa water enters the assembly housing, washes over the resistor, heats, and exits the assembly housing warm.