Installation Instructions for Rough-In Boxes
For Wall Duct Boxes – 4x4 & 4x8 Units
These boxes are intended to be used in walls and have been specially designed to fit within 2x4 walls. This reduces or eliminates the need for additional framing except potentially at the top plate. Generally these products will be installed during the construction of the home so any framing should not be a major issue.
Determining Placement. For venting cabinets, typically the 4x4 unit would be used and this mates with the HiFlo Lite Vent products. The ideal situation would be to install the vent during construction in areas where there will be built-in cabinetry that will need to be vented. The 4x8 unit would be appropriate to vent equipment closets and should be located in either the upper area of a wall or in the ceiling.
For determining the placement of the exhaust end you need to determine where to vent to. Typically you want to vent to an adjacent hallway, closet, or best case scenario, an HVAC return vent. Ensure to consider aesthetics when determining the placement. Another consideration is that you can use boxes interchangeably for the exhaust. In other words, if you use a 4x4 for the fan unit, you can use a 4x8 for the exhaust and then perhaps use a standard and matching 4x8 HVAC grill (4x8 is a standard size for HVAC grills). At the same time, if you use a 4x8 box and HiFlo System for venting a closet, the 4x4 can be used for exhaust if one of those grill options better fit your application.
Installation. Once the placement has been determined and also the route of the tubing, simply screw the unit to the wall or ceiling framing utilizing the drywall flanges on the grills. A horizontal/cross support can also be added so the box is fastened on two sides – one on one of the vertical flanges and one on a horizontal flange. When mounting the boxes, ensure that the opening of the box is square. It is very common for these boxes to be out of square during their production and handling.
Once both boxes are set, the intake and exhaust boxes, then connect the 3” (7.62cm) tubing that you have selected. If running through an attic, ensure to use insulated tubing or ensure that attic insulation will fully cover the tubing – this can be achieved by fastening the duct to ceiling joists that will inevitably be covered with insulation. When connecting tubing, ensure to use an appropriate foil HVAC duct tape and ensure a tight seal has been achieved. Regular ‘duct tape’ is not sufficient as it will break down over time.
Roughing in For Power. When installing the tubing, you can run a power wire through the tubing and into the intake box – just ensure where it enters the tubing is sealed with HVAC tape. This will make for a very clean and easy trim out. Just run the other end of the power wire to the point where you will plug in the power supply. Also note that you can run a standard 2-conductor wire for the power wire and splice on a connector for the fan unit.
Notes. Ensure to follow all code requirements and consult with HVAC or general contractors on your project to ensure that your work will pass inspections. This installation will be new to inspectors and may be scrutinized. All boxes should be completely code compliant but codes do vary greatly from region to region.
Use safety devices and precautions as necessary or as required.