Q139. Would a boiler (or other combustion unit) that is mounted on a trailer or movable platform, that is used to provide temporary services while facility equipment is serviced, upgraded, or replaced, and where such equipment remains at the facility...

A139.  If the fuel-burning equipment on the trailer or moveable platform is moved to different locations on campus during the year as different facility equipment is serviced, then it is considered portable. If the fuel-burning equipment remains in the same spot for more than 12 consecutive months, then it is not considered portable per the definition of "portable" in 40 CFR 98.6.