I would stay away from the Duo-Therm Brisk Air... Get the 13.5 Coleman Powersaver with heat strips..... http://www.pplmotorhomes.com/parts/rv-air-conditioners/coleman-mach-III-pwr-savr.htm

http://www.pplmotorhomes.com/parts/rv-air-conditioners/mach-III-ps-data.pdf

Carrier build a fine unit until they quit a year or so ago.

The heat strips on the AC units are pretty much worthless, at a considerable optional pricing. The best aux heater is a $25 ceramic unit available from many sources. One can easily heat a 13' LQ at below freezing outside temps. They usually draw ~13 amps, are thermostatically controlled, and are far quieter than the main AC fans.

I have two Duotherm AC units, and both work flawlessly into a decade of usage for each. Their strip heaters, however, only serve to warm up a warm space.