最初由 丫丫 发布
Basicly, the new furnaces we bought these years that buring nature gas, which is considered as clean fuel, should not need cleaning as the old ones.
Talking about the ducts, it depends on house clean or dirty your house used to be kept as, the dust could be settled in the ducts and accumulated to such amount that it will pollute air quality once the fan is turued on again after a while.
Changing Air filter every 3--6 month should be a way to keep your air system clean. Get a comercial vacume truck clean the system should you consider the pipe lines are dirty.
This is just my understanding , I will check out more information on this.