All the air you breathe passes thru your furnace, which is why that is where the filter is. But even the very best filters allow 5-8% of the debris to pass thru and most allow 3-4x that to get by. Plus only the hot side of your heating system is filtered. This is why when we clean your ducts that the cold trucks and intakes are so full of debris. While we are cleaning it is strongly recommended that we clean not only the ducts but your furnace as well, this cleaning includes air washing of your a/c A frame which is positioned in your duct work above your furnace. Because of its position it is not cleaned during typical furnace cleaning by gas companies. A dirty A frame can contribute to poor air circulation both in the heating and cooling cycles, and it will make your air conditioning work far less efficiently. We have had clients who have had their out door air conditioners replaced and have found no improvement in their poor a/c operation, only to latter to open the duct work and find an A frame plugged with pet hair. This is an expensive lesson that could have easily been prevented with duct cleaning and furnace cleaning. We can also air wash your heat exchanger, air inlets, furnace fan and housing. We do not dismantle or tune the furnace itself.
The price to clean your furnace with duct cleaning is $89 or for just cleaning the furnace by itself, with out duct cleaning is $129.