Temperature control devices have become common to cool the exhaust stream from a diesel particulate filter before release into the environment. To further cool the filtered exhaust stream and to protect the temperature control device, a duct can be used to surround the inlets of the temperature control device. The duct has a head section surrounding the inlets at one end and a base section extending from the head section with a vent at the other end. Ambient air is drawn through the vent into the duct and into the inlets of the temperature control device to further cool the filtered exhaust stream.