TomG2 wrote:
Could it be as simple as replacing the ducted ceiling unit with a un-ducted one?
Good idea. I thought about that, too. I believe the ceiling assembly itself is the only difference between the ducted and non-ducted a/c rooftop units. Could be wrong tho.
I suppose I could install a non-ducted ceiling assembly which should allow more air-flow directly into the living area than the non-modded ducted ceiling assembly (which is purposely designed to always force some air into the ductwork). However, I believe the ducted ceiling assembly with the baffle assembly cut-out allows much better direct air flow into the main living area then the non-ducted unit. Reason being, the non-ducted ceiling assembly forces most of the air to move at 90 degree angles within the ceiling assembly before exiting.
In any event, I was able to make it out to my unit yesterday to do some more work on the main living area a/c. The ducted a/c unit feeds two sets of ductwork. All the ductwork in my unit appears to be about 2x8 in size and made out of a grey-ish colored, pliable kind of hard foam about 1/4" thick. I blocked off the ductwork that feeds the main living area itself. Don't need it since the baffle mod I did does a much, much better job of cooling the main living area. The other set of ductwork feeds the bathroom vent, then continues on to the front bedroom. The front bedroom has its own a/c unit--so this ductwork is not necessary. We do want some cool air in the bathroom. So, I put some foam just inside the bathroom vent, in the ductwork itself (on the exit side leading to the bedroom) to prevent air from being wasted trying to feed the front bedroom ductwork.
Next I installed a small, curved aluminum baffle just below the squirrel cage fan exit to force some air into the ductwork that feeds only the bathroom. I fabricated it so I can bend a portion of the baffle to adjust the amount of air flow into the bathroom. I adjusted it for just a minimal amount of air-flow, just enough to take the edge off the heat in the bathroom. We don't spend enough time in there to sacrifice cooling in the main living area.
Lastly, just wanted to mention these new, re-engineered Dometic Brisk Air II a/c units are advertised as being more "efficient" and lighter. Yes, the insulating, structural material they used around the compressor, condenser, and fan, insulates better and is lighter. However, electrically this a/c is as inefficient as they come. It's only a 13.5k unit, but it has an LRA (locked rotor amps) of 68 amps---equivalent to the most inefficient 15k units. This high LRA is not an issue while using shore power, but most 3000w generators will have a very difficult time starting it, if at all. Two paralleled 2k Hondas would probably have to be run with the Eco mode off to start them. Finally, it consistently draws 15-16a---roughly 2-3a more than 13.5k units I've used in the past. In this day and age where there's a big focus on efficient use of power and electricity---Dometic spared nothing to make this unit exactly the opposite.
