My contractor is coming next week to insall my new furnace. It is 4" narrower than my old furnace. My contractor wants to place the runace againest the air return and then flair the duct to the side to connect to the larger condenser. It seems to me that you would want the furnace centered below the condenser to get even flow but he says that isn't necessary. I have now confidence in this installer as he is changing out the furnace because he put too big of one in originaly.

Is it okay to have the furnace offset to the condenser by 4" and just have duct flared on the one side?

thanks for your help.