Liquid heaters and vaporizers – Stand boiler – And condition responsive feature
Reexamination Certificate
2000-12-21
2002-04-16
Wilson, Gregory A. (Department: 3749)
Liquid heaters and vaporizers
Stand boiler
And condition responsive feature
C122S017100, C122S019200, C137S487500, C392S455000
Reexamination Certificate
active
06371057
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to gas-fueled water heaters, with particular application to high volume produced water heaters of the so-called “sealed” combustion chamber type. It relates also to methods of their assembly.
BACKGROUND
The cost of high volume production of gas-fueled water heaters of the type with sealed combustion chambers has proven higher than that of conventional ones because of variations in component part dimensions. Although complying with industry norms, when applied to the sealed combustion chamber type, these variations add together to become more dimensionally important and so render high speed assembly more difficult. The assembly of a water heater involves a number of different components including a tank, a combustion chamber, a burner, a gas control valve, a reflecting pan under the burner to protect the floor underneath the water heater from burner heat and numerous other elements, including insulation, being brought together on an assembly line. How well the parts combine determines to some extent the manufacturing cost. The desire to assemble quickly at minimum cost can not be allowed however to prejudice user safety by risking, when a water heater is installed, flammable gas fuel escape from ill-fitting joints.
Over recent years, numerous solutions have been proposed in relation to gas-fueled water heaters in general to address safety and efficiency increases and atmospheric pollution reductions. Some solutions involve “sealed” combustion chambers, for various reasons, discussed below. The great majority of conventional water heaters meeting the same market demands have traditionally had open combustion chambers. An open combustion chamber allows, for example, lighting of the pilot burner through an access hole using a match or taper. Also, the burners utilize secondary air in the combustion process, where that air can enter freely through an inspection or burner service opening.
A sealed combustion chamber type in this context is sealed in the sense that air for combustion is permitted to enter the combustion chamber through designated openings. These include an opening remotely above the heater or outside of the room in which the heater is installed. They may also include a type protected from flame flash-through from inside the combustion chamber. Or, they may only admit air through the burner after it is pre-mixed with the gas fuel. Any so-called sealed combustion chamber in a storage water heater is of course open where the products of combustion escape to atmosphere. Most commonly, this is at the outlet of a single tube passing through the storage tank.
Conventional gas fired water heaters normally include a tank, which contains pressurized water, a water inlet from a mains pressurized supply and a water outlet. Heating of the tank involves a combustion chamber positioned below or within the tank, a gas control valve positioned adjacent an external vertical wall of the tank and a burner positioned within the combustion chamber. As much as possible of the assemblage of parts is thermally insulated.
Conventionally, the gas control valve senses the temperature of water within the tank. When the water temperature drops below a certain minimum, gas is allowed to flow through the gas valve to the burner within the combustion chamber where it is ignited by a pilot burner, heating the combustion chamber and the body of water above (or, less commonly, around) the combustion chamber. The products of combustion are vented through a tube connected to the combustion chamber and passing through the water tank. This conventional construction has been common for many decades. Numerous variations upon this construction have been created in attempts to increase efficiency and otherwise improve operating characteristics.
The desire for sealed combustion chambers includes the following:
(a) The safe operation of gas-fueled water heaters, despite unintended presence of dangerous flammable fumes around the air inlet, has become a particular goal of the water heater industry. The problem that I sought to solve arose in such a context but has broader application in water heaters.
(b) Concern for the environment has made the elimination of potentially polluting substances in the products of combustion more important. Whilst any single gas fired water heater is a very low polluter when compared to many other fuel consuming products, because water heaters are so numerous, any reduction may produce a worthwhile total benefit. Government regulation and stated consumer preference has, therefore, encouraged manufacturers to further reduce the contribution of pollutants emanating from water heaters. Many proposed solutions to reducing such pollutants from water heaters have involved approaches using sealed combustion chambers.
In addition to all of the above very important design improvements proposed, cost is a very important factor in producing water heaters. Water heaters are purchased by builders and home-owners in a very competitive environment. The products are mass-produced, typically on assembly lines running at a rate of up to 250 per hour. Some 5 million gas-fueled water heaters are believed sold throughout the United States of America marketplace each year and national companies compete very aggressively for sales. Water heaters must therefore be very economically manufactured or they will not sell and consumers will not gain the benefits of design improvements.
SUMMARY OF THE INVENTION
The invention provides a fitting connecting a gas control valve to a wall of a water storage tank of a gas water heater, the fitting comprising a substantially vertically extending elongated opening to receive a mating locator attached to the wall, to connect the valve and tank together and allow relative substantially vertical movement whilst connected.
The fitting may include a separate bracket attached to the valve having the elongated opening or may be in the wall of the valve itself. The elongated opening may take several forms, including a parallel-sided slot or an irregular hexagon having a longitudinal axis of symmetry extending substantially vertically or a rectangle having its longer sides extending vertically.
The mating locator may be integral with a pocket extending substantially horizontally inwardly into the tank, the pocket being of a form to enclose a temperature sensor forming part of the valve. Alternatively, the pocket may extend along an exterior surface of the tank wall.
The fitting provides dimensional assembly tolerance in the manufacture of water heaters on high volume production lines and usefully permits relative substantially vertical movement in the range of at least about ⅛
th
to about 2 inches (about 3 mm to about 50 mm).
The fitting further includes a locking device connectable to one of the fitting and the valve, to prevent relative substantially vertical movement of the valve when the locking device is connected to the one of the fitting and the valve and to a part of the water heater.
On completion of assembly, the fitting normally relies for its required firm holding of the valve on the rigid pipe connecting the outlet port of the valve with a burner enclosed in a predetermined fixed position in a sealed combustion chamber fixed rigidly to the base of the tank of the water heater.
The rigidity of the fitting can be augmented by a substantially right-angled tab joining the fitting or the valve body itself to a nearby surface of a jacket of the water heater.
The invention also relates to a method of assembling to a water heater tank, to produce a water heater, a sub-assembly comprising a gas control valve, burner and combustion chamber, the method including the steps of:
a) providing in the water heater tank a pocket to receive a temperature sensor;
b) producing the sub-assembly of the gas control valve, the burner and the combustion chamber, the gas control valve being connected to the burner via at least one substantially rigid conduit;
c) providing an adjustable mount for mounting the gas control valve to the water
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