Method and system in a fluid heating apparatus for efficiently

Abstract

In a fluid heating apparatus having a fluid tank, a combustion chamber communicating with the fluid tank for heat exchange, and a combustible fluid delivery system coupled to the combustion chamber, a plurality of valves are individually configured in either an off-state or an on-state for delivering combustible fluid to the combustion chamber. Depending on the configuration of the multiple valves, the rate at which combustible fluid is supplied to the combustion chamber may be varied in response to a heat demand signal. Individual valve signals are generated for each of the multiple valves in response to the heat demand signal to place the multiple valves in a configuration to supply combustible fluid at predetermined rates. The demand signal is calculated in response to reading temperature at an inlet temperature probe and an outlet temperature probe, wherein the outlet temperature probe is located nearer a fluid outlet from the fluid tank than is the inlet temperature probe. The heat demand signal may also be a function of the excess of a set point temperature over a temperature measured by the outlet temperature probe. An airblower may also be coupled to the combustion chamber and operated in a plurality of modes for supplying air at a plurality of rates in response to the heat demand signal. The rates of air supply provided by the air blower are selected to supply air at a stoichiometric rates in relation to the fuel supply rates provided by various configurations of the valves in the combustible fluid delivery system.