RV Glossary

120 AC/12 DC/LP-gas - The power sources on which RV refrigerators operate; 120 AC is 120-volt alternating current (same as in houses); 12 DC is 12-volt direct current (same as in motor vehicles); LP-gas. Some RV refrigerators can operate on two of the three sources, others on all three. For most of your RV's lighting the 120 AC power is directed through a power converter and reduced to 12V. This operates lights, furnace motors, water pump, TV antenna and other low voltage accessories. See Converter below

ANODE ROD - an anode rod, when used in a water heater, attracts corrosion causing products in the water. These products attack the anode rod instead of the metal tank itself. The anode rod should be inspected yearly and changed when it is reduced to about 1/4 of its original size. The rods are used in steel water heater tanks - an aluminum tank has an inner layer of anode metal to accomplish the same thing. Anode rods should not be installed in an aluminum tank!

AXLE RATIO - The ratio between the pinion and ring gears in the differential that multiply the torque provided by the engine. It is the number of drive line revolutions required to turn the axle one time. As an example, with a 4.10:1 axle the drive line turns 4.1 times for each full axle revolution. The higher the number, the more torque and thus more towing power. However, the higher the number also means less speed and fuel economy.

BLACK WATER - disposal water from toilet system, held in holding tank until you dump it, in large tanks or dumping station available at most campgrounds.

Brake Actuator - a device mounted under the dash of a towing vehicle to control the braking system of the trailer. Most Brake Actuators a based on a time delay, the more time the tow vehicle brakes are applied the "harder" the trailer brakes are applied.

Brake Controller - a device mounted under the dash of a towing vehicle to control the braking system of the trailer. The Brake Controller senses the amount of braking force of the tow vehicle and applied a proportional force to the trailer braking system.

BTU - British Thermal Unit - A measurement of heat that is the quantity required to raise the temperature of one pound of water 1 degree F. RV air-conditioners and furnaces are BTU-rated.

Camber - Wheel alignment - Camber is the number of degrees each wheel is off of vertical. Looking from the front, tops of wheels farther apart than bottoms means "positive camber". As the load pushes the front end down, or the springs get weak, camber would go from positive to none to negative (bottoms of wheels farther apart than tops).

Castor - Wheel alignment - The steering wheels' desire to return to center after you turn a corner.

CONDENSATION - condensation is a result of warn moisture laden air contacting the cold window glass. Keeping a roof vent open helps to reduce the humidity levels. Those added roof vent covers help to prevent cold air from dropping down through the vent while still allowing moist air to escape. Using the roof vent fan when showering or the stove vent fan when cooking also helps prevent excess moisture buildup.

CONVERTER - A converter is device that converts 120 volt A/C (alternating current) to 12 volt DC (direct current). The RV devices mostly run on 12 volt DC power that is supplied by the battery, which allows the RV to function independently. When "shore power" (an electrical supply) is available, the converter changes the voltage from 120 to 12 volt to supply the appliances and to recharge the battery.

DINETTE - booth-like dining area. Table usually drops to convert unit into a bed at night.

DSI IGNITION - direct spark ignition - this term refers to the method of igniting the main burner on a propane fired appliance. The burner is lit with an electric spark and the flame is monitored by an electronic circuit board. This ignition system is used in refrigerators, furnaces and water heaters. There is now a version of stove tops that light the burners with a DSI ignition.

DUCTED AC is air conditioning supplied through a ducting system in the ceiling. This supplies cooling air at various vents located throughout the RV.

DUCTED HEAT is warm air from the furnace supplied to various locations in the RV through a ducting system located in the floor. (similar to house heating systems)

DUAL ELECTRICAL SYSTEM - RV equipped with lights, appliances which operate on 12-volt battery power when self-contained, and with a converter, on 110 AC current when in campgrounds or with an onboard generator.

DUALLY - A pickup truck, or light-duty tow vehicle, with four tires on one rear axle.

GENERATOR - An engine powered device fuelled by gasoline or diesel fuel, and sometimes propane, for generating 120-volt AC power.

GREY WATER - disposal water from sinks, shower. In some units, this is held in a tank separate from black water; is also dumped in tanks at campgrounds.

GROSS AXLE WEIGHT RATING (GAWR) - The manufacturers maximum load weight, in pounds, that can be placed on the axle. If an axle has a 3500-lb. GAWR and the RV has two axles (tandem axles), then the RV would have a Gross Vehicle Weight Rating (GVWR) of 7000 lbs.

GROSS COMBINED WEIGHT RATING (GCWR) - The manufacturers maximum load weight, in pounds, allowed for the trailer and tow vehicle. This rating includes the weight of the trailer and tow vehicle plus fuel, water, propane, supplies and passengers.

GROSS VEHICLE WEIGHT RATING (GVWR) - The manufacturers maximum load weight, in pounds, allowed for the vehicle. This rating includes the weight of the vehicle plus fuel, water, propane, supplies and passengers.

Gross Trailer Weight (GTW) - Gross trailer weight is the weight of the trailer fully loaded in its actual towing condition. GTW is measured by placing the fully loaded trailer on a vehicle scale. The entire weight of the trailer should be supported on the scale.

HEAT EXCHANGER - A heat exchanger is a device that transfers heat from one source to another. For example, there is a heat exchanger in your furnace - the propane flame and combustion products are contained inside the heat exchanger that is sealed from the inside area. Inside air is blown over the surface of the exchanger, where it is warmed and the blown through the ducting system for room heating. The combustion gases are vented to the outside air.

HEAT STRIP - A heat strip is an electric heating element located in the air conditioning system with the warm air distributed by the air conditioner fan and ducting system. They are typically 1500 watt elements (about the same wattage as an electric hair dryer) and have limited function. Basically they "take the chill off"

HITCH WEIGHT - The amount of a trailer's weight that rests on the tow vehicle's hitch. For travel trailers this weight should be 10% to 15% of the total weight of the trailer. For fifth wheels this weight should be 15% to 20% of the total weight of the trailer.

HOLDING TANKS - There are three different holding tanks on most RVs; fresh water tank, gray water tank and black water tank. The fresh water tank holds fresh water that can be stored for later use. The gray water tank holds the waste water from the sinks and showers. The black water tank holds the waste from the toilet.

HOOKUPS - The ability of connecting to a campground's facilities. The major types of hookups are electrical, water and sewer. If all three of these hookups are available, it is termed full hookup. Hookups may also include telephone and cable TV in some campgrounds.

INVERTER - An inverter is a device that changes 12 volt battery power to 120 volt AC power. It is used when "boondocking" (camping without hookups) to power certain 120 VAC only devices like a microwave oven. The amount of available power depends on the storage capacity of the batteries and the wattage rating of the inverter.

LAMINATE - A sandwich of structural frame members, wall paneling, insulation and exterior covering, adhesive-bonded under pressure and/or heat to form the RV's walls, floor and/or roof.

LP GAS - Liquefied Petroleum Gas. LP gas is used to fuel appliances in the RV, such as the stove, oven, water heater and refrigerator. Propane tanks are usually rated as pounds or gallons.

NET CARRYING CAPACITY (NCC) or Payload Capacity - Sometimes called the payload capacity, this is the maximum weight of fuel, water, propane, supplies and passengers that can be added to an RV without exceeding the Gross Vehicle Weight Rating (GVWR).

PILOT - a pilot is a small standby flame that is used to light the main burner of a propane fired appliance when the thermostat calls for heat. Pilots can be used in furnaces, water heaters, refrigerators, ovens and stove tops.

PROPANE - LPG, or liquefied petroleum gas, used in RVs for heating, cooking and refrigeration. Also called bottle gas, for manner in which it is sold and stored.

RIG - what many RVers call their units.

ROOF AIR CONDITIONING - air conditioning unit mounted on roof of RV, to cool the RV when it is parked. When moving, most RVs are cooled by separate air conditioning units which are components of the engine, or they may be cooled by a roof top if a proper size generator is installed.

RV - short for Recreation Vehicle, a generic term for all pleasure vehicles which contain living accommodations. Multiple units are RVs and persons using them are RVers.

SELF CONTAINED - RV which needs no external electrical, drain or water hookup. Thus, it can park overnight anywhere. Of course, self-contained units can also hook up to facilities when at campgrounds.

THERMOCOUPLE - a thermocouple is a device that monitors the pilot flame of a pilot model propane appliance. If the pilot flame is extinguished the thermocouple causes the gas valve to shut off the flow of gas to both the pilot flame and the main burner.

TONGUE WEIGHT - Tongue weight (TW) is the downward force exerted on the hitch ball by the trailer coupler. In most cases, it is about 10 to 15 percent of GTW. TW of up to 300 lbs. can be measured on a household scale by resting the trailer coupler on the scale and placing the scale on a box so that the coupler is at its normal towing height. The trailer must be fully loaded and level.

For heavier tongue weights, place a household scale and a brick that's as thick as the scale three feet apart. Set a length of pipe on each and rest a beam across the pipes. Re-zero the scale to correct for the weight of the beam and pipe. Securely block the trailer wheels. Rest the trailer jack on the beam, one (1) foot from the pipe on the brick and two (2) feet from the pipe on the scale.

To obtain the TW, multiply the scale reading by three (3). For greater tongue weights, place the scale and brick four (4) feet apart, rest the jack on the beam three (3) feet from the scale and multiply the scale reading by four (4).

TOW RATING - This is the rating from the tow vehicle manufacturer. These ratings should be obtained from the vehicle dealership or owners manual prior to selecting the RV that you are going to be towing.

UNDERBELLY - The RV's under floor surface, which is protected by a weatherproofed material.

UNLOADED VEHICLE WEIGHT (UVW) or Dry Weight - Sometimes called the Dry Weight, it is the weight of the RV without adding fuel, water, propane, supplies and passengers. The manufacturers uvw will not include any dealer-installed options.

Waste water tanks - The gray water tank holds the waste water from the sinks and showers. The black water tank holds the waste from the toilet.

WET WEIGHT - The weight of the vehicle with the fuel, freshwater and propane tanks full.

WHEELBASE - Distance between center lines of the primary axles of a vehicle. If a motor home includes a tag axle, the distance is measured from the front axle to the center point between the drive and tag axles.

WEIGHT DISTRIBUTION HITCH - A weight distribution hitch consist of two parts. The first part being the receiver hitch that is mounted to the frame of the tow vehicle. The receiver hitch has two weight ratings, one is weight carrying and one is with weight distribution. Weight carrying is the weight that the hitch can safely tow with a standard ball mount and ball. The weight distribution rating is the weight that can be towed with the addition of a weight distribution package.

The weight distribution package pins in your receiver hitch and then two spring bars are attached to the camper and the receiver hitch. There are several manufacturers and methods used but all have the same simple principal. To distribute the weight evenly throughout the tow vehicle and the towed vehicle. Be sure to consult with and RV professional regarding the installation and operation of the proper weight distribution package as well as any other hitch accessory.