I'm in the process of upgrading the original roof mounted ducted air conditioner.
I searched the forums but could found little specific information.
My specific task is to upgrade the existing 13500 btu unit controlled by the Intellitec load shedding system. (I have a 30 amp service) I'd like to also utilize the existing dual thermostat panel on the wall. The Rooftop unit must be a Dometic BriskAir II that I already own.
From what I've found the cabling differs, the mounting differs and the ducting design differs.
From my research all current units use the "H" shaped duct layout. The front of the unit is the "Return air" and draws hot air form the top of the cabin. The rear output is the "Fresh air" and it blows cold air down from the roof than the air box directs it to the side for connection to the "H", feeding the ducts.
Air Box Design:
My old one is essentially a big grate with a filter inside. The new ones dont pass the fresh air forward through the return air section. But If I bend up a new duct interface module I can make it work. If anyone already knows of such a beast please speak up
My ducting system is straight fore and aft of the unit in the center of the ceiling. Current system layouts are "H" shaped with the unit straddling each side duct with air blowing out to the sides then fore and aft. My front ducts were fed through a removable duct that connected to the "fresh air" output at the rear of the unit. Again bending my own is probably what will need to be done. I feel like I'm the first to do this...
I'd like to use my existing thermostats and shedding system for a few reasons. First I dont have to run any wires (the new ones require a flat phone type cable from the new thermostat to the AC control box. And I dont want two differnt thermostats one abandoned; and I dont want to spend the money! I've looked at the control integration and I'm sure I can splice the old control box to the new rooftop unit but I'd rather make/ buy an interface cable if I can.
This one had me for a little while till I let it digest... The original unit had an intricate ceiling plate with a built in duct feeding fresh air for the forward ducts though the return air portion of the unit. The framing around my unit is steel so I'll jet weld on a few tabs and bolt the unit to them.
So I'll get it going but if anyone can lead me to some shortcuts I would greatly appreciate your help
Ill keep ya'll in the loop for the progress
As usual I started without taking pictures.