My house has 2 zone forced hot water by gas. At the end of last winter the first floor would not heat up to the thermostat setting. I turned the heat down to 64 during the day while at work. When I got home the thermostat reading would be a few degreees below 64. I would then set the thermostat at 72 to heat the place up and it would take an hour to reach 68-70. Out of curiosity I set the thermostat at 80 and it still would not go over 70. A pal who knows a little plumbing checked the thermostat and said it was ok. He pushed a lever on the furnace that he said overrode the thermostat and said the heat pump seemed ok. The baseboard pipes were warm. The house is 11 years old. I got to get this fixed before this winter. Any ideas what the problem could be? Should I call a plumber, a HVAC tech or the local gas company?

Help! i am trying to sell my house but the inspector has told me that my evaporator unit is leaking and its probably the main drain that is clogged. Can anyone tell me how to go about cleaning it.