New construction in Klamath Falls, OR. Note this is 4400′ elevation, east of the Cascades, a high desert basin, not Portland!!

We’re using radiant heat with a high-velocity A/C-only ducted system (Unico) with 7-9″ round rigid metal duct running through open web floor trusses in conditioned space, above a lower level that includes bedrooms and some recreational areas that will be heavily used (i.e. not an unused basement).  The blower and all ducts are fully contained in the conditioned envelope.

I’ve ordered the round metal ducts, but no insulation. Yet…

My understanding is that there are two reasons why I might want to wrap insulation around these trunks – to reduce noise and to reduce the probability of condensation.

Two areas of questions.

First, am I correct in assuming, even though temp differentials in high-velocity systems are higher than traditional A/C, condensation would not be a problem, based on the short cooling season and very low dew point?  We’ll be using a Zehnder ERV, in case that matters.

https://weatherspark.com/m/145275/8/Average-Weather-in-August-at-Klamath-Falls-Airport-Oregon-United-States#Sections-Humidity

Second, any thoughts about whether it’s worth it to incorporate insulation for noise reduction? As mentioned, these ducts run above drywall in two lower-level bedrooms and a rec room, so noise is not welcome.

In addition to general comments about noise level from actual experience, if you have it, I’m also particularly interested in actual data related to sound levels through the pipes and how much a particular thickness of readily available insulated sleeves (I’ve seen 4″, 6″ and 8″ thicknesses) would reduce levels?  I’ve had a hard time finding such information.