US 11,739,983 B1
Modulating gas furnace and associated method of control
Youssef A Jaber, Tyler, TX (US); and Wayne N Kraft, Tyler, TX (US)
Assigned to Trane International Inc., Davidson, NC (US)
Filed by Trane International Inc., Davidson, NC (US)
Filed on Sep. 17, 2020, as Appl. No. 17/24,252.
Int. Cl. F24H 9/20 (2022.01); F23L 17/00 (2006.01); F23N 1/02 (2006.01); F24D 5/04 (2006.01); F23N 5/00 (2006.01); F24H 3/06 (2022.01)
CPC F24H 9/2085 (2013.01) [F23L 17/005 (2013.01); F23N 1/022 (2013.01); F23N 5/006 (2013.01); F24D 5/04 (2013.01); F24H 3/065 (2013.01); F23N 2225/04 (2020.01); F23N 2225/16 (2020.01); F23N 2235/16 (2020.01)] 20 Claims
OG exemplary drawing
 
1. A modulating gas furnace comprising:
a combustion system that includes a burner assembly;
a variable-speed draft inducer blower configured to move air through the combustion system;
a modulating gas valve configured to modulate an amount of fuel delivered to the burner assembly;
a pressure sensor configured to measure combustion system pressure; and
control circuitry operably coupled to the variable-speed draft inducer blower, the modulating gas valve and the pressure sensor, the control circuitry configured to at least:
receive an indication of a firing rate setpoint for the burner assembly;
apply the firing rate setpoint to a first continuous function and a second continuous function that map the firing rate setpoint to an air-to-fuel ratio setpoint and a combustion system pressure setpoint, the first continuous function mapping firing rate to combustion system pressure;
set the variable-speed draft inducer blower to drive to the combustion system pressure setpoint; and
control the modulating gas valve during combustion in the combustion system, including the control circuitry configured to at least:
obtain a combustion system pressure measurement from the pressure sensor;
apply the combustion system pressure measurement to an inverse of the first continuous function that outputs an adjusted firing rate for the combustion system pressure measurement;
apply the adjusted firing rate to a third continuous function that maps the firing rate to gas valve position, and outputs a gas valve position for the adjusted firing rate; and
set the modulating gas valve to the gas valve position.