One such step, and probably the most easily accomplished, is to change the furnace filter. Firstly, turn off the furnace, cutting the electrical power which can be done with a simple breaker. Remove the filter and take note of your filter dimensions. Purchase a new one in the correct size. These can be found at any home improvement store. Depending on what material was used to manufacture the filter, it must be replaced after a specific period of time. It should be changed more frequently if smokers or pets live in the house.
The old filter must be disposed in the trash - never reused. Place the new filter into the filter compartment once you have removed all the packaging materials that came with it. One of the last steps is to make sure that all the screws that keep the filter compartment closed are screwed back into place. Congratulations! You just finished the work and all you have to do now is to turn on the power switch and set the temperature of your thermostat.