Recently I have noticed a powdery white dust like film on my windows and furniture/furnishing. It seems to disperse everywhere .Any ideas.
My gas furnace is regularly cleaned. I have even seen this fine particulate in my closets. There is no odor associated with this, although at night I have sporadically smelled a burning scent that goes away. I have a gas fireplace unit also.
This is actually pretty easy - stop wasting time & money on "cleaning" the ducts & instead get them sealed. The dust that settles in the ducts is not an issue due to the way the air moves through them - the problem is you have some leakage on the return side pulling in who knows what from those areas. With that I would make sure you have both the supply & return ducts sealed up & then a static pressure test performed. This will help them determine if you might need another return in the house, need to adjust some dampers, etc... For more on sealing ducts: http://blog.sls-construction.com/2011/air-sealing-duct-system