Starting last summer 2008, we built a 1500 ft2 addition on to the front of our Church. during this addition we installed a new trunk and plenum to our HVAC System. We started to notice last winter that the new addition was not heating well, and was just kind of cold and drafty. We thought it was just because we didn't have insulation or drywall on the walls yet, but after that was on, it was still cold. So we started closing vents in the sanctuary to get more heat/air pressure in the new addition, which did help bring the temperature up. In the Summer we do not have a problem with cooling the building, the same vents seem to have more air pressure. We called the service people and they said the blower speeds had been turned up for the heat, but still little pressure. The trunk is about 30 feet long, and the additions lines are on the far end away from the furnace. The longest line is probably 50 feet from the end of the trunk. Do you think we need to put in an additional furnace to heat the new part?