Canvas Connector starts as a 100 ft roll packaged in an orange or red box…

Flexible Duct Connector is a nylon fabric secured to sheet metal on both sides and fabricated into the HVAC Ductwork in an area next to the Blower in order to isolate the ductwork from vibrations and noises that might otherwise carry throughout the system

…but once fabricated, ends as a Rectangular Frame Connection in between two joining sections of ductwork.

Canvas Connector as it’s being pulled out of the box

When Canvas Connector has a raw edge all the way around, it’s being attached to Ductmate Flange

There are four Canvas Connection Frames in this picture…can you identify them?

Why Safety is the primary reason 4” x 4” x 4” Canvas Connector is used for TDC/F Duct instead of 3” x 3” x 3”

The Flexible Duct Connection serves to Isolate the Vibration and Noise coming from the unit so it doesnt carry thru the duct system. It is a stretchable fabric bounded on both sides by two sleeves of metal. The fabricator rolls it out of a box and makes it into a rectangular sleeve which is then installed between two ends of ductwork.

TDF Rollformer finishes with TDF profile formed on the edge

3” x 3”x 3” is the most common size when Duct Fabricators are making this flexible connection from Slip & Drive duct. When this rectangular sleeve (aka flexible duct connection) is being used in TDC/TDF duct, 4″ x 4″x 4″ replaces the 3″ x 3″x 3″ as the size most contractors use.

Same product after run through TDF rollformer

Many contractors assume this is because TDC/TDF duct is accommodating more air pressure and larger ductwork. But feedback from most TDC/TDF shops is one simple reason: Safety. Unlike Slip & Drive duct, the TDC/F profile (whether it’s on the Lockformer TDC, Engel TDF or Vicon TDX) uses 2” of the metal edge from the canvas connector. This means that a 3” x 3” x 3” would end up as 1” x 3” x 1”. Going to 4” x 4” x 4” gives a finished product of 2” x 4” x 2”. Using 3″ x 3″ x 3″ would mean that the fingers are dangerously close (1″) to the forming rolls of the machine.

TDF rolled flange from a flat sheet of metal. If this was 4x4x4 canvas connector, the operator’s fingers would be closer to the forming rolls but on 3x3x3 the fingers would be dangerously close

Why turning a 90 degree angle on the Canvas Connector makes sense

The Flexible Duct Connection is a four-sided framed sleeve that serves to isolate vibrations and noise from traveling thru the Ductwork. In it’s preformed state it’s simply a 100 Ft boxed roll consisting of a flexible nylon fabric in the middle with a metal sleeve on either side. Commonly the Nylon is 3” wide and the two 24 ga Sleeves on either side of it are also 3” wide. The Nylon and Metal sleeve are connected securely with a roll formed seam lock. Flexible Duct Connector, when rolled out of the box and formed by the duct fab shop , looks like a 4 sided rectangular sleeve. These sleeves are then taken to job site and positioned between two ends of duct.

Some shops will turn a 90 degree bend on the 4 sides that it not only serves to stiffen the sleeve but it also assists in lining the sleeve up so it more easily connects the two ends of duct making things easier for the install crew.

Canvas Connector: not just for Rectangular Duct

Canvas Connector is occasionally used with round duct