Abstract: A device that, in any situation where multiple streams of hot or very hot gases or exhaust are generated, can collect gases into one stream and divert the stream efficiently to any manner of reformers, treatment devices, scrubbers, exchangers, etc. The exhaust flow from multiple fuel cell stacks are mixed in a single stream within the invention. This must be done carefully so that the exhaust stack pressure is approximately atmospheric at a variety of operating conditions. The mixing occurs in a device (the invention) called a Barometric Thermal Trap (BaTT). The fuel cell exhaust has a fairly high steam and CO2 content. The steam represents a potentially significant source of latent heat. Typical fuel cell heat recovery units avoid capturing the latent heat due to its relatively low condensing temperature (140 degrees Fahrenheit) and the resultant acidic level of the condensate due to the presence of CO2, which forms carbonic acid.