Jacuzzi Hot tub temperature sensor

A spa (also commonly known as a “hot tub” when located outdoors) is a therapeutic bath in which all or part of the body is exposed to forceful whirling currents of hot water. When located indoors and equipped with fill and drain features like a bathtub, the spa is typically referred to as a “whirlpool bath”. Typically, the spa's hot water is generated when water contacts a heating element in a water circulating heating pipe system. A major problem associated with the spa's water circulating heating pipe system is the risk of damage to the heater and adjacent parts of the spa when the heater becomes too hot.

FIG. 1 is a drawing showing the main elements of a prior art hot tub spa system 1. Spa controller 7 is programmed to control the spa's water pumps 1A and 1B and air blower 4. In normal operation, water is pumped by water pump 1A through heater 3 where it is heated by heating element 5. The heated water then leaves heater 3 and enters spa tub 2 through jets 11. Water leaves spa tub 2 through drains 13 and the cycle is repeated.

Some conditions may cause little or no flow of water through the pipe containing heating element 5 during the heating process. These problems can cause what is known in the spa industry as a “dry fire”. Dry fires occur when there is no water in heater 3 or when the flow of water is too weak to remove enough heat from the heating element 5. Common causes of low water flow are a dirty filter or a clogged pipe. For example, referring to FIG. 1, if a bathing suit became lodged in pipe 17B clogging the pipe, flow of water through heater 3 would be impeded and a dry fire could occur.

FIG. 1 shows a prior art arrangement to prevent overheating conditions. A circuit incorporating temperature sensor 50 serves to protect spa 1 from overheating. Temperature sensor 50 is mounted to the outside of heater 3. Temperature sensor 50 is electrically connected to comparator circuit 51A and control circuit 52A, which is electrically connected to high limit relay 53A.