Water heater having condensing recuperator and dual purpose pump

Abstract

A water heater having primary and secondary heat exchanger and a pump to move water between the primary and secondary heat exchangers. The pump may also be used for the purpose of recirculating water within a building. The water heater may be manufactured with a method in which certain steps and components are added to a water heater of a first efficiency to arrive at a water heater having a second efficiency greater than the first efficiency. The additional steps and components may include attaching a condensing recuperator to a traditional power vent water heater.

What is claimed is: 
     
         1 . A water heater comprising:
 a tank-type water heater having a tank adapted to store water, a flue extending through the tank;   a source of hot gas, the hot gas flowing through the flue to heat water in the tank;   a flow-type water heater receiving the hot gas from the flue and heating water with the hot gas; and   a pump for moving water from the tank, through the flow-type water heater, and back to the tank.   
     
     
         2 . The water heater of  claim 1 , wherein the water heater is adapted for use in a building having a hot water supply pipe communicating directly with the tank; and wherein the pump also circulates water from the tank through the hot water supply pipe and back into the tank to maintain a ready supply of hot water in the hot water supply pipe. 
     
     
         3 . The water heater of  claim 1 , wherein the flow-type water heater is a condensing water heater. 
     
     
         4 . The water heater of  claim 1 , wherein the temperature of the hot gas does not exceed 600° F. 
     
     
         5 . The water heater of  claim 1 , wherein the hot gas comprises products of combustion. 
     
     
         6 . A water heater communicating with a hot water supply pipe, the water heater comprising:
 a source of hot gas;   a heat exchanger for transferring heat from the hot gas to water; and   a pump for accomplishing a first purpose related to the water heater;   wherein the pump is also used for a second purpose that includes circulating water through the hot water supply pipe and back to the water heater to maintain a ready supply of hot water in the hot water supply pipe.   
     
     
         7 . The water heater of  claim 6 , wherein the source of hot gas includes a fuel-fired burner; and wherein the hot gas includes products of combustion. 
     
     
         8 . The water heater of  claim 6 , further comprising a tank-type water heater including a tank for holding the water; wherein the heat exchanger includes a flue extending through the tank; and wherein the hot gas flows through the flue to heat the water in the tank. 
     
     
         9 . The water heater of  claim 8 , wherein the heat exchanger further comprises a flow-type water heater through which the hot gas flows and through which the water flows; and wherein the hot gas heats the water in the flow-type water heater. 
     
     
         10 . The water heater of  claim 9 , wherein the flue is a primary heat exchanger through which the hot gas flows first; and wherein the flow-type water heater is a secondary heat exchanger through which the hot gas flows after flowing through the primary heat exchanger. 
     
     
         11 . The water heater of  claim 9 , wherein at least one of the primary and secondary heat exchangers is a condensing water heater. 
     
     
         12 . The water heater of  claim 9 , wherein the first purpose of the pump is to move water from the tank-type water heater through the flow-type water heater. 
     
     
         13 . The water heater of  claim 6 , wherein the heat exchanger includes a primary heat exchanger and a secondary heat exchanger; wherein the primary heat exchanger uses heat from the hot gas to heat the water; and wherein the secondary heat exchanger receives the hot gas from the primary heat exchanger and uses heat from the hot gas to heat the water; and wherein the first purpose of the pump is to circulate water through the primary and secondary heat exchangers. 
     
     
         14 . The water heater of  claim 13 , wherein at least one of the primary and secondary heat exchangers is a condensing heat exchanger. 
     
     
         15 . The water heater of  claim 13 , wherein both of the primary and secondary heat exchangers are condensing heat exchangers. 
     
     
         16 . A method for manufacturing a water heater comprising the steps of:
 (a) assembling a tank-type water heater having a tank adapted for containing water, a flue extending through the tank, and a fuel-fired burner for creating products of combustion to flow through the flue and heat water in the tank;   (b) deciding whether to manufacture a high efficiency water heater; and   (c) if manufacturing a high efficiency water heater, (i) providing a condensing flow-type water heater; (ii) providing a pump; (iii) plumbing the flow-type water heater and the pump to the tank to enable the pump to move water from the tank, through the flow-type water heater, and back to the tank; and (iv) communicating the flue with the flow-type water heater to conduct products of combustion from the flue through the flow-type water heater to heat water in the flow-type water heater.   
     
     
         17 . The method of clam  16 , wherein providing a pump includes providing a pump enabled to circulate water from the tank, through a building recirculation system, and back to the tank, in addition to moving water from the tank, through the flow-type water heater, and back to the tank. 
     
     
         18 . The method of  claim 16 , wherein step (c) includes providing a control system that enables operation of the pump during operation of the burner and independent of operation of the burner.