have lived in this home for over 15 years had the furnace in the attic replaced in December of 2008. just before Christmas it stopped working had an heating guy come out at 3:30 am to check it. he said it had froze up because of the outside temperature also said we had a 90 furnace instead of an 80 that should have been installed. I asked what we could do to prevent it from freezing up again and he said because it was in the attic with two cross vents in the evases there wasn't much we could do. don't want to replace the furnace again so soon as the last time they had to cut a hole in ceiling of a bedroom to get it up there. we purchased this home new it was a spec home. any help or advice would be extremely helpful short of selling and getting over it all. Thanks so much!