Abstract: Heating apparatus for heating of a fluid. The heating apparatus comprises a conduit having a fluid passage therethrough for conduction of a fluid to be heated, a heating device, such as for example electrical heating plates, in heat transfer contact with a portion of the conduit for heating the fluid being conducted therethrough, and a temperature sensing device positioned in engagement with the conduit at a predetermined location along the conduit external to the conduit for sensing the temperature of the fluid to be conducted therepast. A contact member is arranged to engage the flexible conduit at the predetermined location for compressing the flexible conduit to constrict the cross sectional area of the flow passage thereat when the flow rate of the fluid is below a predetermined flow rate. Preferably, the contact member is spring biased towards the flow passage constricting position, and is movable away from such position when the flow rate exceeds a predetermined flow rate.