Patent ID: 8591221

Claim:
A forced air furnace comprising: a burner; a pneumatically modulated gas valve configured to provide gas to the burner; a combustion blower in fluid communication with the burner; and a pneumatic sampling device disposed proximate the combustion blower, the pneumatic sampling device having a first pneumatic sampling port in fluid communication with the pneumatically modulated gas valve via a first pneumatic line for providing a first pneumatic signal directly to the pneumatically modulated gas valve, and a second pneumatic sampling port in fluid communication with the pneumatically modulated gas valve via a second pneumatic line for providing a second pneumatic signal directly to the pneumatically modulated gas valve, the first and second pneumatic signals collectively representative of fluid flow through the pneumatic sampling device, the pneumatically modulated gas valve regulating gas flow in accordance with the first and second pneumatic signals.