Manual D on existing house if all ducts have dampers?
I’m having some home performance diagnostics (blower door, duct leakage, etc.) completed on my house (that was built in 2010), and the contractor has suggested that he perform some HVAC design tests including manual J, manual S, and manual D.
My question concerns manual D. All of the ducts are the kinds that have the dampers on them where the duct attaches to the plenum, so the amount of airflow to the duct at the plenum can be controlled. Duct leakage was within acceptable ranges as shown by the duct blaster test, and with my existing HVAC system (which I am thinking about replacing), air flow and distribution seems fine, all rooms are generally within a degree or two of all other rooms, etc.
Given that I don’t anticipate significant duct work, and all ducts have dampers for some amount of additional control, is it worth it to pay the extra money for a manual D? Or could I skip that?
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