Method and apparatus for utilizing waste heat in hot water heaters

• US 4,821,682 A
• Filed: 07/24/1987
• Issued: 04/18/1989
• Est. Priority Date: 05/08/1986
• Status: Expired due to Fees

• Current Assignee: Larry G. Waters
• Original Assignee: Larry G. Waters
• Inventors: Waters, Larry G.
• Primary Examiner(s): Warner, Steven E.
• Application Number:
  US07/077,635
• Time in Patent Office: 634 Days
• Field of Search: 122/20 A, 122/20 B, 122/13 R, 122/14, 122/17, 122/155 R, 122/166 R, 122/166 A, 122/169, 122/244, 122/245, 122/247, 122/249, 122/250 R, 122/250 S, 237/8 R, 237/19, 126/361, 126/362, 126/364, 126/365, 236/20 R
• US Class Current: 122/20.00A
• CPC Class Codes: F24H 1/18 Water-storage heaters

Abstract

Normally wasted heat from the pilot burner and flue of a fuel fired hot water heater is used to preheat the water supplied to the main tank. An auxilliary storage tank receives incoming cold water. Water from the storage tank circulates through a conduit loop which extends in a spiral pattern through the flue and also through a special heat exchanger which concentrates heat generated by the pilot burner. The water that is preheated in the conduit loop is returned to the storage tank for storage until required by the main tank, at which time the preheated water is delivered to the main tank through a transfer conduit. Alternative embodiments are arranged to effect automatic flushing of the conduit loop when hot water is withdrawn from the main tank.

Claims

1. In a hot water heating system having a main tank, a cold water inlet pipe connected with a supply of cold water to be heated, a fuel fired main burner for heating water in the main tank, a fuel fired pilot burner for igniting the main burner, and a flue in the main tank for discharging combustion gases, the improvement comprising:

a storage tank for holding water which is to be preheated prior to transfer to the main tank, said cold wate rinlet pipe discharging into said storage tank to deliver thereto incoming cold water to be heated;

a conduit loop having an inlet end communicating with said storage tank to receive water therefrom and an outlet end communicating with said storage tank to return preheated water thereto, said conduit loop having an intermediate portion thereof extending in said flue in a generally spiral configuration to extract heat from the flue for preheating of water circulating in the conduit loop; and

a transfer conduit extending from said storage tank to said main tank to deliver preheated water from the storage tank to the main tank to replace hot water drawn out of the main tank.

2. The improvement of claim 1, wherein said intermediate portion of the conduit loop comprises a pair of pipe sections through which water is circulated in opposite directions.

3. The improvement of claim 2, including:

a heat exchanger located adjacent the pilot burner to be heated thereby; and

a conduit section forming part of said conduit loop, said conduit section being located between said pipe sections and extending through said heat exchanger to effect heating of the water in said conduit section.

4. A method of enhancing energy efficiency in a hot water heater having a main tank, a fuel fired main burner for heating water in the main tank, a fuel fired pilot burner for igniting the main tank, and a flue in the main tank for discharging combustion gases, said method comprising the steps of:

delivering incoming cold water to a storage tank;

circulating water from the storage tank through a conduit in a preselected direction to pass the water in the conduit in heat exchange relationship with the pilot burner and through the flue to thereby use the pilot burner heat and the flue heat to heat the water in the conduit;

returning the heated water in the conduit to the storage tank; and

transferring water from the storage tank to the main tank when the main tank calls for water, whereby the water supplied to the main tank for heating therein is preheated to reduce the heating requirements of the main burner.

5. The method of claim 4, including the step of effecting circulation of water through said conduit in a direction opposite said preselected direction at selected times to thereby back flush said conduit.

6. The method of claim 4, including the step of increasing the speed of the water circulated through said conduit at selected times, thereby flushing said conduit.