I just had 2 heat pumps with all associated ductwork added to my >100 year old house, and I have a couple of questions about "standard practices" that they followed.
1) On the second floor most of my ducts were run to ceiling vents, which were run through plaster and a 1 by spacer and paper tile. This would not seem to be a problem, but while they were installing it they sandwiched the lath boards plaster the spacer and the paper tile between the damper and the diffuser. I have a picture of what the hole looks like which I will add to this post. I did not like this as air would blow into my attic and blow plaster dust into the room. When I questioned them they stated it was standard practice. Is this standard practice?
2) They did the same thing where I had a drywall ceiling, and stated on new construction they attached the metal adapter to the flex to the joists and then after drywall was complete the diffusers would screw over top. This does not seem like a good idea to me for two reasons, one is drywall dust will be blown into the room and there is potential for air leaking behind the drywall. Is this standard practice?
3) The first floor air handler was put on the second floor and converted to the flow downward. They only applied foam tape to the air handler and sat it on the floor. When I questioned them they added some silicone and a single duct strap to hold it to the floor. Is this standard practice? What can I do to improve this?
4) Is it important to have the air handler and the heat pump level?
5) Should all seams be taped? In the attic a lot of the elbow to damper connection were not taped and it seems to me they should be.