AC Ductwork & Supply Sizing / Ceiling locations
I had a system put in 10 years ago. I have a split level home and it was installed in the upper attic with a trunk line that drops down into the lower attic and feeds the main level (Kitchen/LR/DR). There was 2 ceiling registers for the LR, 1 in the DR and 1 in the kitchen. Basically the LR was the length of the DR and kitchen combined. Never got really cool down there but we had old leaky windows, crappy insulation. Big 11' window on the east side of the house that would warm things up in the afternoon and non-ic recessed cans that I love were buried in blow in fiberglass insulation.
I am doing a full remodel of this floor. Right now this floor is mostly gutted. New cans will be Air tight IC cans. All new windows and doors. Plan is to also install a front covered porch that would shield the sunlight. I am also planning on dense pack cellulose in the walls and blown in cellulose in the lower part of the attic.
The trunk line is pretty much run high just under the bracing. Otherwise there would be no access to this lower attic through the hatch. This ductwork stole space from the entrance so its tight as it is but can get in if really needed. The floor dimensions are 26'x26'. The kitchen and DR and now 1 room. There was a beam put in between the LR and old DR that is flush. The only doorway is between the Hallway and the kitchen. The hall will be open to the LR, with a half wall. There is the one bearing wall between the LR and kitchen.
Right now there are 4 flex ducts coming off the trunk line. 3 of which are on the sides of the end of the trunk. There are 3 6" lines and 1 7" line. The 7" line was feeding the existing kitchen. There are no straps supporting the ducts and I can see that the airflow is majorly restricted on the 90 degree bends into the ceiling registers. Plan is to use new flex duct with higher r-value. Strap it and also pull the duct wrap off the trunk line(s) and seal with mastic. Fun DIY job.
Question is if the duct sizes are adequate for the space and where is the best positions for them to be placed in the room. Do I use 4? Do I use 2 larger ones centered? Should the duct sizes be larger? Want to correct these issues while the ceiling is ripped down and before I get to the point of having the insulation contractors come.
below is a pic of the layout. Black boxes are current approx locations of the ceiling supply registers (There used to be walls and doorways separating the rooms. The blue lines are approx duct connections. The translucent red/orange rectangle is the approx trunk location. I can take other pics of the actual trunkline, etc later and post if needed.