|I do not believe that people realize that a non-union shop and a company like ours who does not have a tinning shop in house can do commercial work properly. I can not take any credit for the ductwork. As stated, there was nearly two months of planning going into this job.
Key was to engineer the duct based on AIRFLOW....and that is what most guys who are getting their feet wet in light commercial RTU replacements are totally oblivious to.
The area was laser mapped and that was transferred into the computer with my sheet metal guys (Metco Metal). They basically go to work with the engineering for the rooftop, engineering for the curb, and existing roof penetrating duct. All in all, they come up with duct sizing, transition angles, turning vanes, and what all is needed to achieve optimal air flow and at the same time fit 6 pounds of salami in a 2 pound bag. This info was then taken to the curb manufacturer (KCC) and they build to spec what my metal guys need.
All in all everything is delivered on site and their is a lot of nail biting as the pieces all join together like Legos.
The most critical part on the 40 ton unit was setting the curb. That curb had to be perfectly set with no more than a ¼" tolerance. It was decided to set the curb and attach the return air ducting first. It is a whole lot easier to make small adjustments with moving the curb, when there is no rooftop unit setting on it. As soon as the curb and return air ducting was all attached and lined up, the RTU was dropped in place.
Now the real challenge of praying and nail biting that the side discharge plenum off of the RTU unit itself and the transition pieces off of the existing roof supply plenum would all fall into place......and obviously they did. I had my son and a few other boys from the high school football team with buckets of pooky/mastic, go to work after things calmed down.
40 tonner in the air.
Flat beds with the new and the old.
New 40 ton curb and return air duct prepped and ready for the new unit. Took about 40 minutes to attach the new duct, perfectly designed via computer CAD for air-flow and near perfect installation.
40 tonner set, installed, final duct, and final programming/commissioning of system, duct static system, economizer, and freak drives for supply and power exhaust. (SimplicityPC/YORK Millennium...easy-squeazy).
20 tonner in the air...quite the reach. Custom curb and duct all CAD drawn and designed for air-flow...turning vanes and all. Commissioning on this guy was a breeze. Got her tweaked at 1.1"WC...unit is constant volume.
So, in a nutshell, this is just one of many jobs we do, nothing special, I can not take any credit for the ductwork.....I just have the right companies in my pocket to work along side as a team to get the job done properly, accurately, quickly, and professionally.
The mall in question is having a painting company coming out to paint the ductwork with a special heavy epoxy based paint to water seal, weatherproof, rust protect, and at the same time, the mall sets along side a freeway and it is a beautiful sight for an HVAC guy, but can be an eyesore for people driving by.
So choice was made to match paint color of duct with the York paint scheme. Will post picture of that when final.