I've read a few posts replies and have come to the conclusion that the 70,000btu gas furnace is good for us (3000sq ft home). It is efficiency rated at almost a 97 on energy star scale. I notice that cool air blows out of the cold air returns during the time that the furnace is running. No cold draft when furnace is off from intakes or outputs. We plan to insulate the ducting, which is in our walk out, finished basement. What recommendations do you have--is it right that we feel cold air during heating?

Re: cold air return probs

Re Bad Duct design

Since these are not being used for returns on heating cycle