I am going to purchase a portable generator for a few items in my home in the event of power failure. How much power will it take to run my Lennox G71V 110,000 Btu Gas Furance with ECM motor. I utilize this furance in 2 stage mode and not in modulating mode. Stage 2 for heat puts out about 1550-1600 cfms, however it very rarely gets out of stage 1. I will not be using the generator for my AC.