Hello, Part of the reason your heater may not work properly this winter involves it having a dirty filter in it. When the filter gets clogged, it prevents the central heater from taking in and blowing out hot air. The air in your home might be cold or tepid at best. However, you may not know where to locate the filter or with what size and density of one with which to replace it. The contractors from the service you hire will know what kind of heater your furnace takes. They may have the filter already available in their work truck and be able to replace it right away. Contact Gleason Heating and Air Conditioning today or visit https://www.callgleason.com/heating/furnace-replacement-and-repair/