We used Temperature Experts to replace both the furnace and air conditioner at our previous house. They were efficient and pleasant to deal with. For the furnace, I called at 7:30pm at night after it stopped working (in the middle of January). They came out the same night and diagnosed the problem, and replaced the furnace first thing the next morning. Would recommend without hesitation.
Good heating company to deal with, good group of guys to deal with and the ladies in the office are polite and professional to deal with.