Counter-flow heat reduction cycle

A fuel-fired heating appliance comprising:

• a combustion air pipe;
• an exhaust air pipe;
• a heat exchanger coupled to the combustion air pipe and the exhaust air pipe, the heat exchanger comprising a heat exchanger tube and a induced draft blower configured to direct air toward the heat exchanger tube, wherein the air flows over the heat exchanger tube and into the exhaust air pipe;
• and
• a controller configured to:
• determine a call for heat;
• activate the induced draft blower during a normal heating operation;
• determine that the call for heat is no longer present;
• determine that at least 70 seconds have elapsed since determining that the call for heat is no longer present;
• and
• deactivate the induced draft blower.

A method for operation of an ultra-low NOx gas furnace comprising:

• determining, by a controller, a call for heat;
• activating an induced draft blower of the gas furnace during a normal heating operation;
• determining that the call for heat is no longer present;
• determining that at least 70 seconds have elapsed since determining that the call for heat is no longer present;
• and
• deactivating the induced draft blower.