by step 316 start circ off delay wherein the circulator fan delay procedure is enabled the other entry point into the low heating mode routine is checking step 314 the step following start circ off delay step 316 and checking step 314 is where processor 4 1 determines whether the low fault flag is on namely step 318 low fault flag on if the low fault flag is on then control proceeds to high heat step 302 with the low fault flag off processor 4 1 next determines whether the high fault flag is on in step 320 high fault flag on with the high fault flag being off processor 4 1 then determines if the motor fault flag is set in step 322 motor fault flag set with the motor fault flag not being set control unit 4 then determines if a call for low heat exists in step 324 call for low heat if a call for low heat does not exist then control proceeds to high heat step 302 however if the high fault flag is on during step 320 or if the motor fault flag is set during step 322 or if a call for low heat exists in step 324 control proceeds to step 326 turn on low inducer at this point heating may begin by operation of burner 16 because inducer fan 18 now provides air for combustion if step 326 occurs while inducer 18 is.