Must be certified for a trailer is correct but there are other brands with sealed combustion that now are certified for mobile homes including Trane and York. The problem is unless you are going to tear out all the ducts and start over the blowers will not handle the static pressure required by trailer home duct systems. If you are going to use the existing ductwork choose the brands that Jultzya suggested and do not try any other brand unless you like headaches.
Originally posted by jultzya
Must be certified for a trailer installation!
The only companies I'm aware of that are manufacturing products for trailers are...
Coleman, Miller, and Thermopride.
(and of coarse the sister names to these)