DUST AND BOILER: https://www.minisplitheat.com/ Boiler in the use of the process inevitably produce dust and flue gas, boiler dust is the dust from the boiler separated from the flue gas, thereby reducing dust pollution and is conducive to further flue gas desulfurization and denitrification process. According to the function mechanism of dust collector, there are four ways to dust the boiler: 1.Mechanical dust collector: the general role in the dust collector, the dust force is gravity, inertial force and centrifugal force, this kind of dust collector can be divided into: gravity settling chamber, inertial dust collector, centrifugal dust collector (also Called cyclone dust collector). 2. Electric dust collector: also known as electrostatic precipitator, its working principle is to dust particles in the dust charged electricity, in the electric force under the action of the charged dust particles deposited on the surface of the settlement machine. According to the structural characteristics of electrostatic precipitator, there can be a variety of classification, in which the dust collector can be divided into tubular electrostatic precipitator and plate electrostatic precipitator. 3. Filterable dust collector: filter dust removal device is dust gas and filter medium relying on inertial collision, diffusion, retention, screening and other functions, to achieve separation of gas and solid dust removal facilities. According to the filter media and structure of different forms, divided into bag dust collector and particle layer dust collector. 4. Wet dust collector: also known as wet scrubber, with water or other liquids for dust removal facilities to collect the dust particles of the medium, according to the energy level is divided into the low wet dust collector (spray tower, water film dust etc.) and high wet dust remover (venturi filter). https://www.minisplitheat.com/

Blown in or in this case blown over cellulose is not how to insulate ducts. You may have got R50 for the ceiling though. If the contract said it was to insulate ducts you were taken. If all you got was tape on your ducts to seal them, and not a duct sealing mastic, once again taken. Calm down, and yes leaking uninsulated ducts in cold climates will thaw snow down to the overhangs and other cold areas and cause the ice damming.

It could be that the supply box is not sealed to the floor, or ceiling..depending on where the supply air is located. Do you have condensation on the grills? Using a mastic tape to seal this junction will keep dust/insulation particles from entering the home. And is something that you can do from inside the home by removing the grill & sealing the box to the cut in the ceiling (or floor) with a mastic tape. I use Hardcast mastic tape. Often what happens is that when the grill is installed that the screws pick the supply box up..and particles & unconditioned air enters @ this area. Go into your attic..if the supply is in the ceiling & feel around the supply box. If you feel a gap between the box & ceiling..there is the entry of this unconditioned air. Best of luck & let us know what you find.

You have no recourse against the city. The builder should take care of it if still under warrantee. The GC is responsible for the subs work. It should have been the duct guys job, but could be a grey area depending how things are built. That's when it comes back to the GC.