Specifications

Heartland Owners Forum http://manuals.heartlandowners.org
Heating and Cooling Guide V1.pdf Page | 8 Version: 1, March 15, 2013
Generally, with the fan on HIGH speed your discharge temperature at the main air dump should be
about 20 degrees Fahrenheit lower than the air entering at the return air grille. That will hold true up to
about 90-95 degrees outside, when the cooling efficiency begins to go down.
Dometic representatives speaking at the North American Heartland Rally have told owners that at best,
they can expect a 20 degree warmer temperature at the rear corner of the coach, than the air coming
out of the main air dump. If the air coming out of the main air dump is 58 degrees, the rear corner of
the coach may be 78 degrees. This may vary based on trailer layout, size and distance between these
two points.
Cooling efficiency is obviously affected by a number of other factors including:
• Outside temperature and humidity
• Direct sunlight, especially in the afternoon
• Insulation
• Dual pane vs. single pane windows
• Shades and blinds
• Size of the area being cooled
At 4:00 PM in South Florida during August, temperatures will be in the high 90s. Humidity will be in the
high 90s. Very intense direct sun will be on one side of the RV creating a significant heat load. Under
these conditions, in any larger RV, even an air conditioner that works perfectly will struggle to cool the
unit satisfactorily.
Specific tips on managing the air conditioning in hot weather are presented later in this guide.
Humidity
Excess humidity inside the coach puts a very significant load on the system. When the humidity has
been reduced, the heat can be more effectively handled. This is most noticeable when starting the air
conditioner in the late afternoon on a hot and humid day.
Maximize you systems performance by parking in shaded areas, minimizing humidity in the coach by
using vents when showering and cooking, running the fan on high speed, keeping windows and doors
closed as much as possible, closing shades, and turning the A/C on early in the day.
Bedroom Air Conditioner
Compared to the living area, the volume of air that is cooled in a bedroom is far less and doesn’t require
as large an air conditioner. A 13,500 BTU unit is typical. On trailers that have the “Whisper Quiet Air
Conditioning” design, the bedroom air conditioner is integrated into the ductwork, and works together
with the living room air conditioner to cool the entire trailer. The “Whisper Quiet” design is a fairly
recent innovation and is currently available on high-end fifth wheels.
When the bedroom air conditioner is an option, as on most units, it is not integrated into the ceiling
ducts. Rather it has air dumps at front and rear with directional louvers that allow directional control of