There are screens available for 1. Refrigerator vents (require 1 kit for each of the two vents), 2. Water Heater and 3. Furnace. The water heater and furnace kits are simple to install, they are installed to the outside useing a spring to secure them to the existing vents and come with a little tool to help with the install, the refrigerator kits are a different, they are attached to the interior vents and use cable ties to secure the screens to the vents.
Installing all four kits will take less than 30 minutes.