Have propane furnace and would like to reduce the fan speed. The lowest speed is 1300 cfms. The total ceiling registers are ~900cfm. Due to HIGH propane costs the furnace burner count was reduced from 3 to 2 burners and a few rooms are not to be heated any longer. Realizing that it is hard on the blower motor to restrict air flow I am hoping for a way to reduce blower speed to better match furnace output.