The ducted Suburban NT Series propane gas furnaces were used in Airstreams and other vintage trailers from the 1970s and later.  The styles have changed somewhat, but they are generally the same size and shape as the originals, making them the proper replacement furnace for older NT units of a similar BTU rating.

Cabinet size is the same on all models, providing a standardized size with three capacity options (see below). NT Series furnaces are not difficult to install, but some of the internal hot air ducts and gas line locations are slightly different than the original. Using flexible pipe and ducting, you can make the connections to your old system. See below for helpful documents.

All three NT models have two 4" round ducts on the left side and two more on the right side. They also have one rectangular duct on the bottom. When you receive the furnace, the side ducts will be open and the bottom duct will be closed.  The NT30 furnace requires at least 36 square inches of duct coming off the furnace.  The NT34 and NT40 require at least 48 square inches.  That means you must use at least 3 of the 4 side ducts OR the bottom duct with the NT30.  You must use all four of the side ducts OR the bottom duct for the NT34 or NT40. 

To use the bottom duct, you must close the side ducts and use a duct adapter for the bottom.  These parts must be purchased separately.  If you are using all four side ducts, you do not need to buy any additional parts.

All units include:

• Gasket-sealed vent assemblies.
• Energy-saving and low maintenance solid state electronic ignition.
• Long lasting steel gas manifolds for a long life.
• Efficient sealed forced-draft combustion.
• Durable chrome-plated vent caps.
• Operable from wall thermostat (included).
  
• Unit Size: 12 1/2" H x 12" W x 23" D