Patent ID: 6857578

Claim:
In a combination water heating and space heating system having a water heating unit for providing heated water for potable water use and for space heating use, a space heating unit for providing heated air to an indoor space, and a water circulating device for circulating water between the water heating unit and the space heating unit, the space heating unit including a heat exchanger for heating air supplied to the space and an air mover for moving air over the heat exchanger, a method of controlling operation of the system to give priority to providing heated water for potable water use over space heating use in response to a predetermined water temperature condition, said method comprising the steps of: controlling the water circulating device to supply heated water from the water heating unit to the heat exchanger in response to a demand for heating in the space; determining whether said predetermined water temperature condition is present; selectively enabling the air mover to move air over the heat exchanger in response to said demand for heating when said predetermined water temperature condition is not present or, alternatively, disabling the air mover when said predetermined water temperature condition is present; and allowing the water circulating device to supply heated water to the heat exchanger in response to said demand for heating, irrespective of whether said predetermined water temperature condition is present, whereby priority is given to providing heated water for potable water use over space heating use when said predetermined water temperature condition is present without interrupting the supply of heated water to the heat exchanger in response to said demand for heating.