To all the HVAC vets…Is it better to install an attic air handler by hanging from rafters or to install on ceiling joists (with vibration pads)? Should the air handler be insulated?
Thanks in advance.
Joshua,
Your post is not specific enough to provide much of a comment. air handlers are required to be installed according to the manufacturers written specifications. While means of draining condensation, required pan, distance from access, working platforms, lighting, and means of disconnect are dictated by the building codes in affect for your local jurisdiction. As far as additional insulation that would not be advised as it would serve to trap condensation between the air handler cabinet and the insulation causing corrosion.
I agree with what Mark said and in this area, they are mostly hung from unitruts spaning rafters and mounted on spring& rubber isolaters.
Cat walks are necessary on most models for servicing, lighting and service outlet should also be provided out of commen sense or as required by the manufacturer or AHJ. 
Not a bad answer Mr. McHammer:D:D
Well, I have built enough cat walks for them Charley, and I don’t like to run for a light and an outlet to plug my tools. :mrgreen:
You have strange cats never seen one walk in the attic just saying;-)
Well considering that we are both the size of a cat Charley, we might feel like one crawling up there sometimes. Very seldon those walks exceed 22" wide, so we got to keep our balance, right? :mrgreen:
Hello Joshua,
I am a Master unrestricted Sheetmetal Mechanic. I have been in the business for 35 years. If you can hang the unit from the upper trusses or from the roof rafters this is the most proffesional installation for many reasons. However sometimes there simply is not enough ceiling height to hang the unit and building a platform is necesary. The most proffesional device for installing either way is the www.Quick-Sling.com
Hope this helps.