Liquid heaters and vaporizers – Stand boiler – And condition responsive feature
Reexamination Certificate
2000-06-09
2001-09-11
Wilson, Gregory (Department: 3749)
Liquid heaters and vaporizers
Stand boiler
And condition responsive feature
C122S507000, C137S337000, C236S012120, C236S012160
Reexamination Certificate
active
06286464
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is generally directed to water heaters and more particularly pertains to enhancing the ability of a water heater to supply hot water.
Water heaters are typically controlled so as to limit the temperature of water contained therein to about 140° F. with the intent to reduce the likelihood of accidental scalding at the point of usage. While such a low set temperature may reduce the likelihood of injury, it does compromise the ability of a water heater of a given size to supply hot water. The heating capacity of most water heaters cannot keep up with the continuous withdrawal of hot water. As cold water replaces the hot water withdrawn from the heater, the temperature of the water within the water heater will gradually drop off thus reducing the output water temperature. The ability of a water heater to quickly recover its set temperature is further aggravated by the fact that the burner is not activated until the temperature of the water drops well below its set temperature. In order to reduce unnecessary cycling, the gas valve that controls the flow of gas to the burner is typically configured to maintain the water temperature within±12° F. As a result, a significant drop off of the water temperature will have occurred before the water heater even begins to heat the water.
Efforts to increase the ability of a water heater to satisfy the demand for hot water without raising the set temperature, have previously been limited to increasing the volume of the tank, increasing the heating capacity of the burner or both. However, the size of the space dedicated for the installation of a water heater in most residential applications limits the maximum size of the water heater. Moreover, a water heater with a larger tank and possibly a larger burner would significantly increase the cost of the water heater.
A water heating system is needed which is capable of providing an increased amount of hot water for a given tank volume and burner size without increasing the temperature at which the hot water is delivered. Additionally, it would be most advantageous for such system to be adaptable to existing water heater configurations and further to be retrofitable to existing water heaters.
SUMMARY OF THE INVENTION
The present invention overcomes the shortcomings of previously used approaches for enhancing the ability of a water heater of given tank volume and burner size to supply hot water. Moreover, the device of the present invention serves to increase the volume of hot water that is available without an increase in the maximum water temperature that is supplied to the point of usage. Alternatively, the present invention may be configured to supply hot water at two temperatures, a very high temperature for usage in for example a dishwasher or washing machine where there is little likelihood of direct contact with a user, and a reduced temperature for usage where direct contact with a user routinely occurs such as in sinks, showers or bathtubs.
The present invention provides for the combination of a mixing valve with a water heater to automatically combine hot water issuing from the water heater with cold water to yield an output at a constant temperature. As a result, the heater may be set to a significantly higher temperature without an increase in the water temperature that is routed to the various points of usage where additional cold water is combined with the mixed water to arrive at a desired temperature. By maintaining the water contained within the water heater at a higher temperature, more hot water at the regulated temperature is ultimately available for use. Additionally, the valve may be configured to supply both unmixed hot water exclusively for use through certain dedicated distribution lines to for example a dishwasher or washing machine, while mixed water at a lower temperature is available for uses where a user will come in direct contact with the water.
Additional advantages associated with the system of the present invention include the fact that a variably positionable gas control valve is no longer required for regulating the temperature of the water within the water heater as a single, high setting is all that is required. Additionally, while a gas control valve is typically configured to regulate the temperature of the water within the water heater to within±12° F. of the set temperature, the mixing valve of the present invention is able to regulate the output water temperature to within about±3° F. of the set temperature.
More particularly, the mixing valve used in the system of the present invention consists of a valve body that is attached directly to the water heater and in which the mixing of two water flows is controlled such that an output flow of a constant temperature is achieved. The valve may be controlled either by a mechanical device such as a wax pellet type thermostat or by an electronic device wherein a thermocouple is relied upon to feed back a temperature signal to a controller which operates a stepper motor with which the position of the valve is adjusted. The output from such valve is then distributed in the usual manner wherein an additional mixing with cold water is accomplished at the point of usage.
The valve may additionally have an unmixed hot water outlet through which very hot water is distributed to points of usage where no direct contact with the user is anticipated. Such devices may for example include dishwashers or clothes washers where the additional temperature is needed and a user is not normally in a position to come in contact with the water.
These and other features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments which, taken in conjunction with the accompanying drawings, illustrate by way of example the principles of the invention.
REFERENCES:
patent: 3958555 (1976-05-01), Horne
patent: 4611757 (1986-09-01), Saether
patent: 5400961 (1995-03-01), Tsutsui et al.
patent: 5503183 (1996-04-01), Fenn et al.
patent: 5623990 (1997-04-01), Pirkle
patent: 6059193 (2000-05-01), Braathen
Abraham Anthony W.
Joubran Raymond-Paul
Fulwider Patton Lee & Utecht LLP
Robertshaw Controls Company
Wilson Gregory
LandOfFree
Water heating system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Water heating system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Water heating system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2463330