KnuckleHeads Prevent Split Tip-overs in High Winds
Roof-mounted heat pump splits are often attached to 4’ X 4’ treated wood beams, which are loose laid on the roof membrane. While this has been common practice for many years, the emergence of taller “double stacked” units has created a new problem: “wind sailing.” Contractors and building owners have reported that taller loose-laid splits attached to wood beams tip over in strong winds. Some contractors have proposed increasing the weight of the base by shifting to 6’ X 6’ beams, but there is a growing trend toward getting wood off the roof. The KnuckleHead system from GreenLink can provide a better solution with more options and flexibility. The KnuckleHead system offers two approaches: Attached or loose laid.
Where attachment is required, the universal KnuckleHead base features multiple holes in its center, which allows for screws for anchoring to the roof deck. Strut Knuckleheads support standard channel, which in turn supports cross rails to which the split is bolted. GreenLink Adhesive/Sealant can be used to seal around the base to prevent leaks.
The same configuration can be loose laid where attachment is not required as long as the elevation does not exceed 12 inches. In either case, the configuration is available as a kit ready for assembly, which includes four strut heads, channel and cross rails cut to length, and necessary hardware. Whether attached or loose laid, the
height can be adjusted by rotating the strut head to ensure that the splits are perfectly level.
For installations that exceed 12 inches, a different configuration is recommended. Higher elevations increase the risk of tip-over in strong winds. GreenLink has designed a special heavy-duty base with an increase in diameter from 7 inches to 12 inches. The vertical strut element is already imbedded in the head surrounded by an internal seal. The kit then features these four vertical elements with base, as well as two cross rails for mounting the split. Height adjustment is accomplished by elevating or lowering the metal rails up to a maximum height of 18”. The rails can be slide adjusted to achieve exact leveling.
Whether attached or loose laid, KnuckleHeads offer an efficient, stable solution to prevent split tip-overs even in the highest wind conditions