Electric resistance heating devices – Heating devices – Continuous flow type fluid heater
Reexamination Certificate
2002-10-01
2003-11-04
Campbell, Thor (Department: 3742)
Electric resistance heating devices
Heating devices
Continuous flow type fluid heater
C392S453000, C392S465000
Reexamination Certificate
active
06643454
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to heaters for maintaining the temperature of a personal jetted bath, and particularly to an assembly of a heating control unit and a bath temperature maintenance heater element.
BACKGROUND OF THE INVENTION
Many consumers have installed jetted bathtubs in their residences for relaxation. Hotels often also provide their guestrooms with jetted tubs, and likewise the same may be provided by therapeutic facilities. Jetted baths are typically filled with hot water from a tap. The hot water is drawn from the tub, passed through a pump, and reintroduced into the tub through jets to provide a soaking user with therapeutic and invigorating jets of water. As the tub is used during a soaking session, the temperature of the water in the tub gradually cools due to heat loss through the tub wall and to the ambient air. To avoid this cooling, some jetted tubs may be provided with a heater installed in the water circulation system. The heater is used to maintain the bath temperature at near its original temperature.
Early jetted bathtub heaters evolved from spa heaters. A spa heater must not only maintain the temperature of the large water volume contained in the spa, but also must initially raise the temperature of the water from ambient to the desired elevated temperature. Spa heaters having heating capacities of 1500 watts to 3000 watts have been used to maintain the temperature of much smaller jetted tubs, even though those outputs were excessive in relationship to the reason for providing a bathtub heater in the first place, i.e.: to maintain the water temperature of the bathtub to the bathers individual comfort level. A secondary heat source (other than the domestic hot water tank) is required only to rectify the loss of heat due to the cooling of the bath water below the bather's comfort level. Such cooling may be caused by the induction of air into the bath water, or the cooling effect of the bath water over time, or the inability to add additional water to the bath water from a domestic hot water tank that had been exhausted in the initial filling of the tub. While bath heaters must have an output sufficient to maintain the bath temperature during use for these reasons, such heaters need not initially heat the bath water from ambient, and thus have much lower actual power requirements than for a heater used in a spa.
Conventional bath maintenance heaters are larger in heat capacity than strictly needed to maintain bath temperature, as noted above. Therefore, conventional heaters must be regulated to assure they do not heat the bath water to above a safe upper limit. In designing a bath heater, there is also a need to limit the function of such conventional high-output heating devices when abnormal conditions are encountered that would produce an unsafe condition, due to excessively heating the water. The anticipated unsafe conditions include, (based upon the heaters ability to produce unsafe heating levels): dry fire, low flow, restricted flow, interrupted power (allowing for residual heat build-up in the heater vessel), and temperature-regulating control failure. Therefore, a temperature-regulating controller and high level limiting device have been required to avoid a heater operating in an unsafe condition, such as those noted above.
SUMMARY OF THE INVENTION
The present invention provides a temperature maintenance heater assembly that maintains temperature within a control range by selecting a heater element with a maximum power rating such that it is not capable of heating the water to a point where the water temperature at the outlet exceeds a specified temperature when running continuously. Further, temperature control is also maintained by a flow switch, which will shut off the heater element when low flow or no flow of fluid is present in the piping.
In accordance with aspects of the present invention, a temperature maintenance heater assembly for maintaining the temperature of a previously heated fluid circulating through piping of a bath is provided. The heater assembly includes a heating element having first and second electrical contacts, and a predetermined maximum power rating. The predetermined maximum power rating of the heating element is selected such that the temperature maintenance heater assembly maintains the fluid immediately upstream of the heating element within a specified safe temperature range with the heating element operating continuously at its maximum power rating. The heater assembly also includes a flow switch having an open state and a closed state. The flow switch is electrically connectable to a power supply and at least one electrical contact of the heating element for supplying electricity therebetween. The flow switch acts to interrupt the supply of electricity to the heating element when a threshold value of fluid flow through the piping is not met, the control assembly continuing the supply of electricity to the heating element whenever the threshold value of fluid flow is met. The heater assembly is absent of a control device that controls the electricity supplied to the heating element based on the temperature of the heated fluid.
In accordance with another aspect of the present invention, a heater assembly for heating fluid circulating through piping of a bath is provided. The heater assembly includes a pipe section having an outer wall, an inlet, and at least one outlet, wherein the fluid is circulated through the pipe section between the inlet and the outlet. The heater assembly also includes a mounting structure attached to the outer wall of the pipe section. The mounting structure has an upper surface and a lower surface. The heater assembly further includes a flow switch mounted to the mounting structure and including a pivoting actuator. A portion of the pivoting actuator partially extends into the interior of the pipe section. A heating element is also included in the heater assembly. The heating element has first and second electrical contacts, and is partially housed within the pipe section between the inlet and the outlet. At least one of the electrical contacts is conductively connected to the flow switch. The flow switch is operable to interrupt the supply of electricity to the heating element when a threshold limit of fluid flow through the pipe section is not met, and to continue the supply of electricity to the heating element whenever the threshold limit of fluid flow is met.
In accordance with still yet another aspect of the present invention, a temperature maintenance heater assembly of a hydro-massage bath having a fluid capacity and operable for maintaining the temperature of a heated fluid circulating through piping of the bath is provided. The heater assembly includes a pipe section with an outer wall, an inlet, and at least one outlet. A heating element is included that is housed partially in the pipe section. The heating element has a first and second electrical contacts and a maximum power rating, wherein the maximum power rating of the heating element is selected based on the fluid capacity of the bath. The heater assembly further includes a control assembly coupled to the pipe section. The control assembly includes a flow switch. The flow switch includes first and second electrical terminals and a switch actuator pivotally movable from an at-rest position, wherein the flow switch is in an open position, to at least one different position remote from the at-rest position, wherein the flow switch is in a closed position. The control assembly is conductively connected to at least one of the electrical contacts of the heating element.
In accordance with still another aspect of the present invention, a pipe section for a heater assembly of a bath is provided. The pipe section includes a center pipe segment sized and configured to accept a heating element therein, and a pipe branch selectively coupled in fluid communication to the center pipe segment. The pipe branch extends transverse from the center pipe segment when coupled thereto and includes an end flange
Alpha-Western Corporation
Campbell Thor
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