We needed a new furnace and got six estimates. The approaches of the various estimators was very interesting. Several of the estimators just looked at the size of the furnace and recommended that we install the same size furnace. One estimator got the utility usage for our house and sized the furnace based on a calculation; he suggested furnace size that was 25% smaller than the old furnace. (I don't know if it would have heated on the coldest days. The fifth contractor also suggested a furnace that was the same size as our old furnace, but he was one of two contractors that clearly explained the differences between the different models of the two furnaces that he recommended. He clearly explained the difference between a modulating furnace and a two stage burner. He also described the differences in the fan motors and warranties. Olson's estimator was the owner. He, like the fifth contractor explained the features and the warranties of the furnaces. He was the only one that adequately answered my question about how far back I could set back the thermostat when we left for extended periods of time. (The furnace installation instructions specified that the cold air intake for the furnace should net be below 55 degrees.) He also was the only one to actually measure the house; he took a copy of the house plan that we had. He did a heat loss calculation based on Manual J. The heat loss calculation showed that the building heat loss was right at the border line between two furnace sizes. I was afraid that the smaller furnace would not be able to keep up during very cold and windy days. I choose the larger furnace; it happened to be the same size as my old furnace. Between the last two contractors, I choose Olson. I was also interested in replacing my air conditioner (a job I put off). Olson also took the time to explain the pay back for different air conditioner efficiencies. (He did the same for the furnaces too.) They have a guarantee that if you are dissatisfied with the performance or equipment during the first 24 months that they will remove the equipment and refund the purchase price. We set an appointment. They showed up on time and completed the installation in a day. There was a minor issue with the installation; they came out immediately and rectified it. It has been about three weeks and the equipment is working well. We would recommend this contractor to our friends and neighbors.