I have a gas furnace with a force air system, 12 years old. I get it clean regularly + change the air filter.
Since may, everytime, it goes on, the warm air smell burnt dust. The contractor came and cleaned the furnace but it still smells. I wash with water the outside of the heat exchanger. I vaccum the air-conditionner and it runned all summer, so it is not the air-conditionner.
I don't think it is the duck system because it smell just above the heat exchanger.
Any idea ?
Should I change the furnace ?
Is that rust ?