Here at V2T we get this question from consultants, architects and contractors on a weekly basis.

Yes, there are significant differences in the Kelly System and the V2T Vent Technology. 

The first and most important difference is the geometry of the two systems, Kelly’s vents are one way valves( a breather valve) that are positioned approximately 5’ from the perimeter and are designed to transfer the negative pressure created by the vortex from the wind coming over the perimeter edge( the negative zone) underneath the membrane.  This will accomplish an equalizing pressure under the membrane created by the negative zone vortex.  The V2T Vent Technology geometry has a vent design that utilizes the Venturi principle through the opposing two hemispheres that will accelerate the wind through the vent. This now creates a negative pressure that is greater than the uplift pressure that is being exerted on the roof. These vents will be positioned approximately 20-25’ from the perimeter where the wind coming over the perimeter will reconnect to the roof surface and be accelerated through the vent.  We use an air distribution highway to transfer this negative pressure back to the perimeter edge.  The significant difference is the additional negative pressure generated by the V2T Vent Technology. In essence a 40 mph wind will generate a negative uplift pressure on the roof. Kelly will equalize the 40 mph pressures, while the V2T Vent Technology will accelerate this wind to greater than 40 mph and transfer this additional negative pressure generated under the membrane.  The Kelly system is a passive system that simply transfers the negative pressure while V2T is an active system that generates greater negative pressures under the membrane than what is being exerted on the roof surface.

The second difference is the positioning and principles of operation of the two systems.  Because Kelly system is designed to operate in the negative zone the vents must be positioned on the perimeter edge.  Therefore the vents on the windward side will be the only vents that will be operational.  However since the V2T Vent Technology is engineered to be positioned in the interior of the roof, all vents on the roof are operational which is a 400% increase in the functional vents on any given roof.

The third difference is the methods of installation. The Kelly System has requirements of securing the perimeter edge and penetrations with OSB board attached to the deck and adhering the membrane to the OSB board.  The V2T Vent Technology does not have these requirements. Although both systems require air seals at the perimeter and around penetrations, the methods of accomplishing this are different.  The Kelly System requires the air seals at the deck level whereas the V2T Vent Technology in general does not.

The fourth difference is the manufacture’s backing of the system.  The Kelly system is an independent system supported by 2001 Company and warranties issued from 2001Company.  The V2T Vent Technology is partnered with and supported by membrane manufacturers; Carlisle Syntec, Versico, FiberTite and Flex who will issue warranties to the building owner’s using the technology.

The fifth difference is in the added technology capabilities.  The V2T Vent Technology has the capability of installing a monitoring system in the vents which are equipped with sensors that can measure and wirelessly communicate, pressure, moisture, heat, wind speed or any other parameter that could be useful on the roof, in real time. This sensor capability will allow contractor’s, manufacturer’s, building owners or maintenance departments to see the performance of the roof, whether the drying effect, the pressure profile, the heat gain or loss or actions on the roof that will alert them to changed conditions on the roof such as a breach or leak in the roof.

These are a few of the highlighted differences, there are others such as the drying effect difference of the two systems which should be obvious from the fact that all V2T Vents are operational across the roof as opposed to just the windward side vents on Kelly’s system, the recycle advantages of no glued areas on V2T versus Kelley.  The versatility of using numerous manufacturers’ materials and the benefits of the relationship with these manufacturer’s versus just one.

In general we believe that the V2T Vent Technology has a significant advantage in performance, installation, monitoring, environmental stewardship and cost than any other system on the market.  To date we have millions of square feet of roof that is providing this benefit to contractors, building owners and manufacturers across the country.



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