Having a house that is frequently colder than you like can be a sign of many different things, and not all of them may be related to your furnace. In fact, some have nothing to do with your furnace at all. Before you call a furnace repair technician, rule out the following.
Open Doors and Drafty Windows
A vast amount of your heat can slip out an open door or a window that is not properly closed. Worse still, a lot of cold air from outside can seep in. Always check your doors to make sure they are closed all the way. Check for drafts around the edges of the doors. If they are drafty, consider replacing them or finding a way to seal them against the cold (e.g., rubber gaskets as edging). Check all of your windows. The storm glass should be drawn down to prevent the cold from going through the screens (if applicable) and then through the frames and creases of your windows. If you have any drafty areas after you have slid the storm glass panes down into position, use weather stripping and window plastic to seal the windows to keep more heat inside.
Make Sure You Are Not Experiencing High Blood Pressure, Hormonal Shifts, or a Thyroid Condition
It sounds weird, but different health conditions can affect how you perceive warmth in your home too. If you know that you do not have high blood pressure (which can cause fluctuations in body temperature), a thyroid condition (which controls your body's ability to regulate temperature), or mid-life hormonal changes, then you can examine the furnace a little closer. Knowing that no personal medical condition is responsible for the cold you feel in your home reaffirms that the problem is most likely with your furnace.
Now Call the Furnace Repair Technician
If you have ruled out all of the above, you can call the repair technician with confidence. If the technician puts any questions to you regarding what you think the problem is, you can answer by letting them know what is not the problem. Then the repair technician can start from there, checking everything from the ignition button to the electric circuit board to the fuel (if applicable). The thermostat may need to be checked as well, so make sure the technician can get to the thermostat without having to push things aside or squeeze past tight spaces.