Quote:
Originally Posted by Jolly Roger
To me a ducted unit is made to push/force air through several dust runs within a structure so a single ducted style unit on the roof that is sleeved straight through to the bus interior to a 4-way throw style of register will way out perform its intended design and last year's longer.
It was designed to push air through many restrictions of twist and turns that go into ductwork that slows down the airflow and creates resistance on the fan motor and blade. So a unit designed to run with a restriction will over perform without one. Maybe to the point that you need to add a speed controller to slow it down?
Maybe you only need one? or two if you have built seperate zones /walls that seperate spaces?
Sorry I do commercial HVAC and ducted to me has a different perspective and I have know clue what an RV ducted unit does?
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you pretty much have it right... a ducted RV unit uses smaller flatter ducts that require a higher statuc pressure and velocity to the air..
the iones Ive seen, the ceiling level as a whole is slightly lowered as the thin but wide ducts are mounted below the insulation layer.. there are rooftop units made for this type of installation...
of course there is basement / central air.. where the ducts are in te floor or are run partially up the interior walls (as to not worry about insulation compromise on outside walls...
ducted rooftop units are fairly rare from what ive seen... even the really large coaches end up with multiple roof-top units and simply run the ones they want in the rooms they are.. I suppose the best case for a ducted unit ive seen would be a duct to the bedroom so the door can be closed.. (a whole unit for a bedroom would be over-kill in most skoolies).. and a duct to the bathroom just because the bathroom is cramped when showering it helps with moisture..
otherwise I dont see a good case to use ducting..
you definitely want it below tour ceiling insulation layer or you will have condensation and heat gain issues...
ive never torn the ciling ducts open in a camper to know what the OEM's use for duct..
I also dont know what the velocity and pressure of the various rooftop units are capable of...
-Christopher