Consumer Reports did a pole on reliability or incidence of repairs,
worth reading. Get bids to have the whole job done. For 200 removing it
yourself is not a good idea especialy messing with gas lines etc. Get
bids, get referrals. Be sure you also get a written load calculation
done , oversizing is a common mistake. The installer is the key to a
good job. In a cold area look to 93-94.5% efficient units they should
cut your bills in half.