Fluid handling – Processes – With control of flow by a condition or characteristic of a...
Reexamination Certificate
1999-07-08
2001-03-06
Walton, George L. (Department: 3753)
Fluid handling
Processes
With control of flow by a condition or characteristic of a...
C137S014000, C137S062000, C137S115130, C137S115180, C137S218000, C137S334000, C137S340000, C137S512300, C137S564000, C137S565150, C137S565290, C137S565330, C122S504000, C237S080000, C417S014000
Reexamination Certificate
active
06196246
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to freeze-resistant plumbing systems in structures located in areas where the ambient temperature declines to a point below freezing, causing water within existing plumbing systems to freeze and damage or destroy the plumbing systems.
BACKGROUND OF THE INVENTION
In cold climates, water in plumbing systems tends to freeze and expand when exposed to temperatures below freezing. When structures are vacant or when water pipes are either exposed or located in attics or exterior walls, the expansion of frozen water may cause the pipes to rupture, leading to water damage when the pipes thaw and water flow resumes.
Keeping water moving throughout the system is effective in preventing water from freezing in the pipes during a cold spell. Hence, people open faucets to drip, maintaining water movement. However, this practice wastes water and may cause water pressure problems.
Prior art methods use circulating water to prevent frozen pipes. U.S. Pat. No. 4,672,990 describes a system with restrictive connections between the hot water and cold water supply lines. However, migration of water between the lines would result in “warm” cold water and “cool” hot water. Further, the increased pressure caused by the circulating pump could pump water back into the main water supply, contaminating it.
U.S. Pat. No. 5,318,059 describes a method of warming cold water by mixing it with hot water and conducting it to the cold water main line. Again, the homeowner would get “warm” cold water or “cool” hot water.
SUMMARY OF THE INVENTION
The present invention is a true water circulatory system, with no expensive branch lines, by-pass lines, shunt lines, or cross-connects. The cold water circulation system is separate from the hot water circulating system, with a separate circulating pump for each system. The system requires no large mixing tanks or space-consuming expansion tanks. When the ambient outdoor temperature drops below a predetermined temperature (e.g. 34° Fahrenheit) a temperature-sensitive switch will energize the circulation pumps, forcing the water to flow continuously through the system. The system operates in conjunction with a backflow preventer with a pressure relief valve; when the circulation pumps are running, the operation of the backflow preventer will prevent water from being pumped back into the main water supply. No pressure relief valve is required for the water heater in this system. Ordinary plumbing materials such as copper and CPVC (chlorinated polyvinyl chloride) pipe are used in building this system. Valves are fixed to the pipes by pipe threads, bolts, flanges, adhesives, welding, or other available means.
It is an object of this invention to provide a freeze-resistant plumbing system for residential and commercial applications.
Yet another object of the invention is to provide a freeze-resistant plumbing system which does not require mixing cold water with hot water in order to prevent freezing.
A further object of the invention is to provide a freeze-resistant plumbing system which is inexpensive to install and operate and which requires little space.
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Gaskin Mary J.
Walton George L.
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