Thermofit Wraparound Heat Shrink Duct Bands (TWDB*) Installation Guide

Thermofit Wraparound Heat Shrink Duct Bands (TWDB*) Installation Instructions

TWDB is heat-shrinkable tape for sealing duct joints on round air conditioning or heating systems.

Materials and Equipment Needed for Install:

1. Raychem TWDB (supplied with high temperature closure tape)
2. Raychem torch (or equivalent)
3. Propane gas tank, regulator and hose
4. Gloves

Recommended TWDB tape widths:

Duct to Fitting to 24" -2” width
Duct to Fitting > 24" -3” width
Duct to Duct ³ 12” -2” width
Duct to Duct 14-48” -3” width
Duct to Duct > 48” -4” width

1. Join duct sections using internal couplers or crimped end male/female type connection. Apply sheet metal screws. 2 screws 180° apart are usually sufficient.

2. Wipe joint area to remove foreign materials. Preheat joint to remove moisture and burn off surface oil that may be present.

3. Cut TWDB to appropriate length. See sizing chart on reverse side. Center TWDB and wrap around duct joint.

4. Using the Tyco Adhesives supplied high temperature tape, secure the loose TWDB end by taping in place.

5. Using a standard propane torch, heat TWDB on all sides until it has shrunk uniformly and adhesive is showing at each end.

6. Smooth down the overlap area with gloved hand to ensure proper contact to duct.
Note: See below for rectangular and flat oval duct.

                                                                                                                                                                      

TWDB may be used to seal
rectangular ducting. The proper
length to cut is shown below.

Length of TWDB
=2 + Perimeter
=2 + 2 (L+W)
Dimensions in inches.
Note: Be sure to measure outer
dimensions as size on print often
refers to internal dimensions.

TWDB may be used to seal flat
oval ducting. The proper length
to cut is shown below.

Length of TWDB
=2 + Circumference
=2 +2.2 Square root of A2 + B2
Dimensions in inches.
Note: Be sure to measure outer
dimensions as size on print often
refers to internal dimensions.

*Install TWDB on rectangular and flat oval duct following the procedures for round duct with the following additional step: Immediately after shrinking is complete, press down the still hot TWDB with roller or gloved and on flat sections.