Water heating apparatus, especially for pools

Abstract

A water heater for heating water includes a burner assembly (54) for generating a flow of hot gas. The burner assembly (54) includes a gas burner (52) and means (64) adjustable to determine a heat output of the burner assembly (54). The water heater further includes a heat exchanger assembly (20) for transferring heat from gas to water flowing therein. The heat exchanger assembly (20) has a higher temperature zone (110) and a lower temperature zone (100). The water heater is arranged to convey the flow of hot gas to the higher temperature zone (110) and in turn to the lower temperature zone (100). The water heater further includes ducting (22, 23) to conduct said flowing water to and from said heat exchanger assembly (20), means (40) to monitor the temperature of the hot gas intermediate the higher temperature zone (110) and the lower temperature zone (100), and control means (70) responsive to the temperature monitoring means (40) to modulate the heat output of the burner assembly (54) whereby to maintain the monitored temperature within a predetermined range so as to substantially prevent or minimise condensation of vapour from the hot gas in the higher temperature zone (110). There is also disclosed a modular heat exchanger apparatus (20) including like headers (34) for redirecting fluid within respective modules (24) and for interconnecting modules (24). There is also disclosed a water heater having a condensate duct (84) to direct condensate into the water for chemically treating the water.

Description

FIELD OF THE INVENTION[0001]This invention relates generally to water heating equipment, but has particularly useful application to pool and spa heaters. Respective aspects of the invention are concerned with a novel configuration of water heater, with a heat exchanger arrangement useful in pool and spa heaters, and with a practical use for the condensate that is a by-product of certain types of water heaters.[0002]Throughout this specification, the term “pool” includes in its ambit any kind of confined water body in which humans can be immersed, including spas, swim spas and Japanese-style immersion tubs.BACKGROUND OF THE INVENTION[0003]Pool heating is conventionally effected either by circulating the pool water through solar panels, typically roof-mounted, or by means of gas-fired water heaters. Water heaters for this purpose are designed to heat a continuous flow of water circulated from the pool to a target temperature in a range comfortable for swimming, and so the requirements...

AI Technical Summary

Benefits of technology

[0015]control means responsive to said temperature monitoring means to modulate the heat output of the burner assembly whereby to maintain the monitored temperature within a predetermined range so as to substantially prevent or minimise condensation of vapour from the hot gas in the higher temperature zone.

[0016]By modulating the heat output of the burner the monitored temperature can be maintained within a pre-determined range without reducing the volume of water flowing through the heat exchanger thereby improving efficiency. It is desirable to minimise said monitored temperature in order to maximise efficiency.

Problems solved by technology

Because of the relatively high water volume and relatively low water temperature, these systems must address the problem of condensation in the gas stream as it passes among the heat exchanger tubes: the condensate is slightly acidic because of the uptake of combustion products, and is therefore a corrosive by-product.

A popular material for the heat exchanger tubes is cupronickel, which is especially susceptible to corrosion by the condensate.

It has been discovered that operation at this very low power level results in low flue temperatures such that condensation and corrosion is particularly problematic.

This approach places limits on the efficiency achievable with the overall heater configuration.

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