RV Glossary

(Blue links are clickable and lead to a detailed article)

• 120 AC / 12 DC / LP-gas: The power sources on which RV refrigerators operate. 120 AC is 120-volt alternating current (same as household power); 12 DC is 12-volt direct current (same as motor vehicles); and LP-gas is propane. Some RV refrigerators operate on two sources, others on all three.
• ANODE ROD – An anode rod, when used in a water heater, attracts corrosion-causing elements in the water to protect the tank. Inspect yearly and replace when reduced to about 1/4 of its original size. Used in steel water heater tanks only (aluminum tanks do not use removable anode rods).
• AXLE RATIO: The ratio between the pinion and ring gears in the differential that multiplies engine torque. It indicates the number of driveline revolutions required to turn the axle once (e.g., a 4.10:1 ratio turns the driveline 4.1 times per axle revolution). Higher numbers provide more towing power at the cost of top speed.
• BLACK WATER – Wastewater originating from the toilet system, held in a black water holding tank until dumped at a proper RV dump station.
• Brake Actuator: A device mounted under the dash of a tow vehicle to control trailer brakes. Most rely on a time delay where longer brake application increases trailer braking force.
• Brake Controller – A proportional control device mounted under the dash of a tow vehicle that senses vehicle deceleration force and applies matching proportional force to the trailer brakes.
• BTU (British Thermal Unit): A measurement of heat energy defined as the amount required to raise the temperature of one pound of water by 1°F. RV furnaces and air conditioners are rated in BTUs.
• Camber (Wheel Alignment): The angle of the wheels relative to vertical when viewed from the front. Tops of wheels tilted farther apart than bottoms indicates positive camber.
• Caster (Wheel Alignment): The angular displacement of the steering axis that enables the front wheels to self-center after turning a corner.
• CONDENSATION: Moisture formed when warm, humid air contacts cold surfaces like window glass. Keeping roof vents slightly open or using exhaust fans while cooking/showering helps reduce indoor humidity.
• CONVERTER – An electrical device that converts 120V AC shore power into 12V DC power to run 12V appliances and charge house batteries when plugged into electrical hookups.
• DINETTE: A booth-style dining table and seating area that typically converts into an extra bed at night.
• DSI IGNITION (Direct Spark Ignition) – An electronic circuit system that uses an electric spark to ignite and monitor the main burner flame on propane appliances like furnaces, water heaters, and fridges.
• DUCTED AC: Air conditioning system that distributes cool air throughout the RV using ceiling-mounted ductwork and adjustable registers.
• DUCTED HEAT: Heating system that distributes warm air from the furnace using floor ductwork and vents.
• DUAL ELECTRICAL SYSTEM – An RV electrical setup operating on 12V DC battery power when boondocking, and on 120V AC power via a converter when connected to shore power or a generator.
• DUALLY: A tow vehicle or pickup truck equipped with double rear wheels (four tires on the rear axle) for increased payload and stability.
• Equalizer Hitch – Also called a weight-distributing hitch; a specialized travel trailer hitch system designed to balance tongue weight evenly across all axles of both the tow vehicle and trailer.
• GENERATOR – An engine-powered auxiliary unit fueled by gasoline, diesel, or propane that generates 120V AC electricity when away from shore power.
• GREY WATER – Wastewater collected from sinks and showers, stored in a dedicated grey water holding tank until emptied at a dump station.
• GROSS AXLE WEIGHT RATING (GAWR) – The maximum structural load weight, in pounds, specified by the manufacturer that an individual axle assembly can safely support.
• GROSS COMBINED WEIGHT RATING (GCWR) – The maximum allowable combined weight of the fully loaded tow vehicle and fully loaded trailer combined, including cargo, fluids, and passengers.
• GROSS VEHICLE WEIGHT RATING (GVWR) – The maximum allowable total weight of the individual vehicle (or trailer) fully loaded with fuel, water, LP gas, cargo, options, and passengers.
• Gross Trailer Weight (GTW) – The actual total weight of a fully loaded trailer in towing condition as measured on a vehicle scale.
• HEAT EXCHANGER – A sealed chamber inside a furnace where propane combustion occurs. Room air is blown over the warm outer surface of the exchanger while combustion exhaust is safely vented outdoors.
• HEAT STRIP: An electric heating element (typically around 1500 watts) added to an air conditioner unit to provide supplemental warmth and take the chill off indoor air.
• HITCH WEIGHT – The downward force exerted by a trailer coupler onto the tow vehicle's hitch ball. Should average 10%–15% of total weight for travel trailers, and 15%–20% for fifth wheels.
• HOLDING TANKS – The onboard storage tanks in an RV: fresh water tank (potable supply), grey water tank (sink/shower waste), and black water tank (toilet waste).
• HOOKUPS: Connections at a campsite providing municipal services. "Full hookups" include city water, electrical power, and sewer connections.
• INVERTER – An electronic device that transforms 12V DC battery power into 120V AC household electricity for operating appliances when camping off-grid.
• LAMINATE: A composite wall, roof, or floor structure made by bonding frame members, insulation, inner paneling, and exterior skin under heat and pressure.
• LIVABILITY PACKAGES: Equipment packages (linens, cookware, utensils, towels) supplied with rental motorhomes for daily living.
• LP GAS – Liquefied Petroleum Gas (Propane) used to fuel RV stoves, ovens, furnaces, water heaters, and absorption refrigerators.
• NET CARRYING CAPACITY (NCC) / Payload – The maximum weight of personal cargo, fluids, occupants, and options that can safely be added to an RV without exceeding its GVWR.
• PILOT – A small continuous flame used to ignite the main propane burner when heat is called for by a thermostat.
• PROPANE – LPG fuel supplied in portable cylinders or permanently mounted tanks for heating, cooking, and refrigeration.
• RIG: A popular term used by RVers to describe their motorhome, travel trailer, or truck setup.
• ROOF AIR CONDITIONING – An AC unit mounted on the RV roof to cool the living space when connected to shore power or running a generator.
• RV: Short for Recreational Vehicle; a generic term for motorized or towable vehicles containing living quarters.
• SELF CONTAINED: An RV built to operate independently without external water, sewer, or electrical connections for short periods.
• THERMOCOUPLE – A safety sensor placed in a pilot flame that automatically cuts off gas flow if the pilot light goes out.
• TOAD – RVer slang for a dinghy/passenger vehicle towed behind a motorhome.
• Toe (Wheel Alignment): The degree to which the fronts of opposing wheels are closer together (toe-in) or farther apart (toe-out) than the backs of the wheels.
• TONGUE WEIGHT – The actual downward force exerted on the hitch ball by a travel trailer coupler (typically 10%–15% of GTW). Can be measured using specialized hitch scales or a beam-and-bathroom-scale arrangement.
• UNDERBELLY – The bottom structural underside of an RV, often enclosed with a protective, weatherproof membrane.
• UNLOADED VEHICLE WEIGHT (UVW) / Dry Weight – The baseline weight of an RV as manufactured at the factory, excluding fuel, fresh water, LP gas, personal cargo, or dealer options.
• Waste Water Tanks – Dedicated holding tanks storing grey water (sinks/shower) and black water (toilet).
• Weight Distributing Hitch – Also called an equalizer hitch; a specialized hitch setup that distributes tongue weight evenly across all axles of the tow vehicle and trailer.
• WET WEIGHT – The total operational weight of an RV with full fresh water, fuel, and propane tanks.
• WHEELBASE: The distance measured between the centerlines of a vehicle's primary front and rear axles.