I am trying to determine what type of heat exchanger is in my geothermal HVAC unit. The model nomenclature gives 4 options but none of the options listed match the model number on my unit. On the Bryant model nomenclature the actual option is listed as "coax option".The complete model number is 50YCD030LLA301. The options are C, D, N, P but mine is an "A". What's the A stand for?

Bryant distributers have this info. Usually unless you are a dealer the info is basically not available to the general public since in most cases you have to have attended a special class to sell and install the equipment. If you know a Bryant dealer in your area you can probably request it from them or contact the dealer that did your install.

Many times the original paperwork is left near the unit so you might look around especially near the floor joist if it is a basement install.