Sizing

• The sizing of the range hood becomes an installation issue if it is not correct. According to the U.S. Environmental Protection Agency, an exhaust that is too large may depressurize the home or cause backdrafting. The general recommendation for a home range hood is 100 cfm -- cubic feet per minute or how fast the unit vents the area. Consult with a contractor or kitchen specialty store if you need help determining the best size. The physical size of the hood's structure is another issue. If the surround is too large for the space, you'll need to reconfigure the cabinets or get a different range hood.
  
  

Outdoor Access

• A range hood needs to vent directly to the outdoors, particularly if you have a gas range. You should not vent your range hood into the attic or other areas of the home. Depending on the placement of your range, access to the outdoors may be challenging. For an interior wall placement, you may need to vent up and over to get to an outside wall. An island range or cooktop also requires creative venting, which might include straight up through the roof or up and over to a side wall. Once you figure out how to get it outside, you may face obstacles like wiring or other structures in the path of the venting pipes.
  
  

Alignment

• A range hood requires proper alignment of components to look right and function correctly. You need to center the hood over the range while keeping an even alignment with the cabinets above and beside it. You also need to cut the hole for the duct properly so it lines up with the actual hood. The exterior hole has to line up with the duct as well. If you don't measure, cut and install properly, your ducts won't line up properly, making it impossible for the unit to work the right way.
  
  

Improper Connection

• Another potential problem in the installation process is in the connections for the range hood. The hood needs to be connected to the power source and to the ducts that carry the exhaust outside. An improper electrical connection could cause a short, fire risk or interruption in power to the unit. Improper duct connections could lead to exhaust that doesn't make it all the way outside.