When your furnace and the accompanying duct work are behaving as they should, the only noise you should hear is the sound or air being forced through your vents. If your furnace makes a loud banging noise when it kicks on, then something is amiss. There are two possible causes for this issue -- each of which is rather easy for your HVAC technician to fix.
Cause #1: Delayed gas ignition.
The fans in a central air conditioning unit play vital roles in the cooling process. There are two key fans, one each in the outside condensing unit and in the inside air handler. The condensing fan helps keep the condensing coils cooled while they convert gas refrigerant to liquid – a process that causes the coils to become hot. Inside the home, a fan cycles the air from your home across evaporator coils, which converts the refrigerant to a gas and becomes cold.
If your home is very dry during the winter, you may have considered buying a portable humidifier, or you may already have one. There are definitive advantages to getting a whole-house humidifier installed on your furnace instead.
More Even Humidity
A portable humidifier emits mist that's suitable for a relatively small amount of square footage, whereas the whole-house model sends moist air through the ducts into each room. People can then get the benefits of optimum humidity throughout the house.