I need to do this very soon. Recently I discovered I need a new furnace, mine was installed when the house was built in 1963. Now the heating contractor gave me an estimate of $3,500 for an 80% efficiency furnace, that seems like highway robbery since I have found 93% furnaces for less than $1,000. I know I will need adapters for the new furnace but that seems like the only special part I will need. My father has offered to come down and help me ( he lives two hours away) and has a experience replacing/installing furnaces. I'm very confident we can do this and save between $1,000-$1,500 safely. Does anybody have experience replacing old natural gas furnaces with high efficiency ones?

What is your question I am sure there is lot guys who have experience changing furnaces

I need to do this very soon. Recently I discovered I need a new furnace, mine was installed when the house was built in 1963. Now the heating contractor gave me an estimate of $3,500 for an 80% efficiency furnace, that seems like highway robbery since I have found 93% furnaces for less than $1,000. I know I will need adapters for the new furnace but that seems like the only special part I will need. My father has offered to come down and help me ( he lives two hours away) and has a experience replacing/installing furnaces. I'm very confident we can do this and save between $1,000-$1,500 safely. Does anybody have experience replacing old natural gas furnaces with high efficiency ones?
I'm just wondering if anybody has had any real trouble doing this. What are some of the problems I should expect to run into to?

Follow the directions that come with the new furnace EXACTLY as stated other wise you can and will have problems. Get permits if necessary to keep your home owners policy valid This way with a permit you can show that the work was done to the instructions just in case something happens someday.

My stupid neighbor a few years ago installed a wood stove without permits. They had a fire and his insurance company never did pay off. He had to make a small loan to fix his house plus the insurance company canceled his policy. Then he went to another company and had to pay a premium because all the insurance companies swap information. It was a bad deal for him do not let it happen to you.