Tall VRFs/Mini-Splits: Blowing in the Wind? Here’s an Answer.

Mini splits are becoming increasingly popular on commercial buildings as well as residential housing. Usually, they can be mounted on any number of support systems, but the taller, narrower profile of the larger units creates a level of vulnerability. In windy conditions, it can tip over, even if mounted. The greater surface area of the taller units acts like the sail on a boat or the wings on a plane: it creates a much higher level of lift compared to the smaller unit.


The best approach to securing taller mini-splits is a mechanical support system that can be attached to the roof. To be effective, such a system requires certain features: It must first of all provide an extremely secure installation; additionally, it has to be adjustable in terms of height, but also in terms of the types of the equipment it will be supporting, meaning that while it is effective with mini-splits, it is also effective with AC units, condensers, etc. Finally, given the competitive bid environment that contractors face on every job, it must be reasonably priced and easy to install. Green Link Engineering has designed a proprietary elevated mechanical support assembly, which provides the type of security needed when taller mini-splits, as well as other wind-sensitive types of HVAC equipment, are mounted on the roof. The elevated mechanical support assembly meets all the requirements to be effective. First, it is attachable. The universal KnuckleHead base features four holes at the center for driving fasteners directly into the roof deck.


This provides an extremely solid foundation for the support assembly. GreenLink Adhesive/Sealant can be used to both seal around the base to prevent leaks, as well as adding bond strength to the installation. The system can also be installed without attachment by using the Big Base, which provides a larger diameter and footprint. Next, stanchion supports consisting of channel molded into a tough polyurethane component are engineered to rotate onto the center bolt of the universal base to form a solid connection. Four support rails can then be horizontally positioned onto the vertical stanchion supports allowing for easy height adjustability. The support rails bolt into place and can be finely adjusted to achieve exact height and leveling. Finally, two equipment rails are designed to slide along the horizontal channel sections to precisely fit the dimensions of the mini-split. These features fulfill the challenge of securely mounting the taller mini-split unit. One last feature: The mechanical support assembly is available in kit form so that all components are on hand to assemble, whether on the roof or the ground. With a little practice, a contractor should be able to build the unit in about 15 minutes.