Specifications

Heartland Owners Forum http://manuals.heartlandowners.org
Heating and Cooling Guide V1.pdf Page | 11 Version: 1, March 15, 2013
Electrical Loads
A/C Units
Air conditioners are rated for their capacity in British Thermal Units (BTUs). The higher the BTU rating,
the more capacity it has to move heat, and the more electricity it requires.
All of our RV air conditioners run on 120 volts AC. If you have two air conditioners on your coach, your
coach will also have what is referred to as 50-Amp RV electrical service. The 50-Amp service consists of
two 120 volt, 50-Amp circuits. The circuit breakers in the main circuit breaker panel each use one leg or
the other of 50-Amp service.
Each rooftop air conditioner gets power from a separate circuit breaker. Typically, to spread the
electrical load, one unit will be powered from the first 50-Amp leg, and the other from the 2
nd
leg.
Like all motors, the air conditioner has a large inrush of current when it first starts, and then the current
drain is reduced after its motors come up to full speed. The initial inrush only lasts for a couple seconds.
A 15,000 BTU A/C unit will have a line voltage inrush current of about 19.8 amps, and back down to
about 9.5 amps when running. It will be fed by a 30-amp circuit breaker.
A slightly smaller 13,500 BTU unit will have a line voltage inrush current of about 19.4 amps and back
down to about 9.0 amps when it is running. It will be fed by a 20-amp circuit breaker. You might notice
that the 19.4 amp inrush current is quite close to the 20-amp circuit breaker rating. That is normal, as
the load would have to remain over the 20-amp circuit breaker rating for more than a few seconds to
trip the circuit breaker.
These electrical numbers are approximate and can vary with conditions. One determinant of the actual
current that you could see is the voltage applied to the motor. The lower the voltage, the higher the
current will be. Excessive current is what will cause circuit breakers to trip, or the motor in the air
conditioner to overheat. A drop in the voltage of only 10 volts will cause the current to increase by
about 2 amps. This can easily happen due to overloaded circuits in campgrounds, or by using extra long
or under-rated extension cords.
An electrical management system/power surge protector that protects against low voltage conditions
will protect your air conditioners by shutting off power to your rig should the voltage become
unacceptably low.
30 Amp Campground Electrical Service
If you are limited to a 30-Amp campground pedestal, you will likely only be able to run one air
conditioner at a time, and very little else.
12V DC for the Thermostat and Air Conditioners
The thermostats in your RV use 12-volts DC for control voltage. If you have a problem with 12-volt DC
supply (from either the power converter and/or batteries) your air conditioner will not operate. Note
that the 12-volt fuse panel has separate fuses for front A/C, rear A/C, and for the furnace.