Thanks for your info but do you have a model no. for a coleman or miller furnace that is 90+ efficient? All the ones we've checked on say they are 80 which is what ours is now. Do you recommend we keep this or replace? I'd hate to spend money to replace if we are going to get same results as now.

Hi! Our double-wide was purchased new in 2000 and is approx. 1600 sq. ft. The furnace is a Miller M1MB 090A BW which is located in our utility room at the end of the house. It's enclosed with walls on 2 sides but the front is exposed. Our heat bills have been really high although we keep the thermos...