Originally Posted by
Scott Patterson
You need to check with the AHJ for the area. They might not require them to go through the roof. Some allow them to terminate in the attic; Some allow them to terminate at a soffit vent; Some allow them to terminate in a vent like the one in your picture. In my area they must terminate outside of the building envelope (out the roof or wall). But, one town down the road allows them to terminate at a vent.
IRC says that they must terminate to the exterior of the home.
The two underlined ones are not allowed by code, and, while the AHJ has the right to "interpret" the code, they do not have the right to "change" the code.
Look at the manufacturer's installation instructions - if those show three going into one, seal around all three to keep the air outside, otherwise, do it like is shown in the installation instructions (I've never seen where three into one have been shown in the installation instructions).