Plain-English RV terms.

RV culture has its own language. BTU, GVWR, dinghy, boondocking, Schwintek. Here's a no-nonsense glossary so you can read forums and rental agreements without Googling every other word.

Power

120V system: The AC electrical system in an RV that runs off shore power, generator, or inverter. Powers ACs, microwaves, residential fridges, and standard wall outlets.
12V system: The DC electrical system in an RV that runs off the house battery. Lights, water pump, fans, slide motors, and most controls are 12V. Distinct from the 120V (shore power) system that runs ACs, microwaves, and outlets.
30 amp service: A common RV electrical hookup with a single 120V leg providing 30 amps total. Found at most campgrounds. Will run one AC plus light loads but not two ACs at once.
50 amp service: A higher-capacity RV hookup with two 120V legs providing 50 amps each (100 total). Required for big rigs running two or three air conditioners. Cord uses a four-prong plug.
Converter: The 120V-to-12V power supply that charges the house battery and runs 12V systems when on shore power. Often combined with the breaker panel into a 'power center.'
Generator: An onboard 120V power source, usually propane, gas, or diesel. Common brands: Onan (Cummins), Generac. Runs ACs and outlets when shore power isn't available.
House battery: The deep-cycle battery (or bank) that powers the 12V systems. Separate from the chassis battery that starts the engine. Can be flooded lead-acid, AGM, or lithium.
Inverter: A device that converts 12V battery power to 120V AC for running outlets when not plugged in. Distinct from the converter, which goes the other direction.
LP: Liquefied petroleum, the propane stored in onboard tanks. Powers the stove, water heater, furnace, and absorption fridge.
Onan: Brand of generators owned by Cummins. The most common RV generator. QG and Microquiet models are widely used.
Shore power: 120V electricity from a campground pedestal, typically 30 amp or 50 amp service. Runs the converter, ACs, and standard outlets.
SOC: State of Charge. The percentage of battery capacity remaining. Lithium batteries display this directly; lead-acid is estimated from voltage.

Plumbing

Black tank: The waste holding tank that collects everything from the toilet. Dumped at a sewer hookup or dump station via the black valve handle.
Black tank flush: A built-in spray nozzle inside the black tank for rinsing residue after dumping. Connect a fresh water hose to the flush fitting outside the rig.
Bypass valve: Valves that route water around the water heater during winterization to keep antifreeze out of the tank. Must be in the normal position for the water heater to work.
Dump station: A facility where you empty the black and gray tanks. Found at most campgrounds, truck stops, and many gas stations. Always dump black first, then gray to flush the hose.
Fresh tank: The onboard water tank that supplies the rig when not connected to city water. Filled via a gravity fill or pressure fill port. Capacities range from 30-100+ gallons.
Gray tank: The holding tank that collects water from sinks and showers. Drains separately from black tank. Dump black first, then gray to rinse the hose.
Macerator: A pump with a built-in grinder that lets you dump waste through a small garden hose instead of a 3-inch sewer hose. Common on Class B vans.
Pyramid clog: A pile of solid waste that builds up directly under the toilet outlet because the black valve was left open. Fix: close the valve, fill with water, drive, then dump.
Water heater bypass: Valves that route water around the water heater during winterization. Must be in the normal/summer position for the water heater to work.
Wet bay: The exterior compartment housing the water hookups, manifold, and dump valves. Usually heated on four-season rigs.

Appliances

Absorption fridge: A propane/electric RV refrigerator that uses ammonia and a heat source instead of a compressor. Common brands: Dometic, Norcold. Requires the rig to be level to work properly.
BTU: British Thermal Unit. Used to rate AC and furnace cooling/heating capacity. A 13,500 BTU rooftop AC is the most common size on travel trailers.
Compressor fridge: An RV refrigerator that uses a 12V compressor like a household fridge. More efficient than absorption, doesn't require leveling, but draws steady amps from the house battery.
Residential fridge: A standard household refrigerator installed in an RV instead of an absorption or 12V compressor unit. More capacity, more efficient, but draws constant 120V or inverter power.

Mechanical

ATF: Automatic transmission fluid. Used as the hydraulic fluid in many Lippert and HWH leveling systems. Dexron III/Mercon V is the most common spec.
CCC: Cargo Carrying Capacity. The total weight of cargo, water, propane, and passengers an RV can safely carry. Found on the federal weight sticker near the door.
Dry weight: The weight of the RV with empty tanks and no cargo, as it left the factory. The lowest meaningful weight number, real-world weight is much higher.
GVWR: Gross Vehicle Weight Rating. The maximum total weight an RV can safely operate at, including the rig, all cargo, fluids, and passengers. Never exceed.
Leveling jacks: Hydraulic or electric jacks that extend from under the rig to level it on uneven ground. Common brands: Lippert, HWH, Bigfoot.
Schwintek: A Lippert in-wall slide-out system that uses gear tracks built into the slide walls. Lighter and simpler than through-frame systems but more prone to racking.
Slide-out: A room section that extends outward to expand the rig's living space at camp. Driven by hydraulic, electric, or rack-and-pinion mechanisms.
UVW: Unloaded Vehicle Weight. The weight of the RV as built, with no cargo, water, or propane. Same general idea as 'dry weight.'

Rig types

Class A: The largest motorhome class, built on a heavy-duty bus or truck chassis. Looks like a tour bus. Lengths 26-45 feet. Highest capacity, lowest fuel economy.
Class B: A camper van. Built on a Mercedes Sprinter, Ford Transit, or Ram Promaster chassis. Smallest motorhome class, drives like a van.
Class C: A motorhome built on a cutaway truck or van chassis with the recognizable cabover bunk above the cab. Lengths 22-32 feet. Most common rental class.
Fifth wheel: A large travel trailer that connects to a hitch in the bed of a pickup truck instead of a bumper hitch. Distinguished by the raised front section over the truck bed.
Pop-up: A small folding camper trailer with canvas walls that fold down for towing. Lightweight, towable by smaller vehicles. Also called a tent trailer.
Travel trailer: A bumper-hitch towable trailer. Lengths 12-40 feet. The most common RV type. Distinguished from fifth wheels by the standard ball or weight-distribution hitch.

Towing

Dinghy: A small vehicle towed behind a motorhome for local errands. Also called a 'toad.' Most are flat-towed on all four wheels with a tow bar.
Hitch weight: The downward force a trailer puts on the tow vehicle's hitch. Should be 10-15% of total trailer weight for stability. Too low and the trailer fishtails.
Toad: RV slang for a vehicle towed behind a motorhome. Pronounced like 'towed.' Same as 'dinghy.'
Tongue weight: Same as hitch weight, the downward force a travel trailer puts on the tow vehicle's hitch ball.

Camping

Boondocking: Camping without any hookups (no power, water, or sewer). Requires self-sufficient water, battery, and waste capacity. Also called dry camping or dispersed camping.

Maintenance

Dicor: Brand of self-leveling lap sealant used to seal RV roof penetrations. The 501LSW formula is the industry standard for EPDM and TPO roofs.
EPDM roof: Ethylene propylene diene monomer rubber roofing. The original RV rubber roof, looks like soft black material under a white coating. Most rigs before 2015.
Geo Method: A black tank cleaning method using Calgon water softener and laundry detergent to clean stuck tank sensors and break down residue. Long-running RV forum favorite.
Lap sealant: Self-leveling sealant used on horizontal RV roof seams (vent flanges, AC mounts). Dicor 501LSW is the industry standard.
TPO roof: Thermoplastic polyolefin roofing. A stiffer, smoother white plastic-like material replacing EPDM on most modern RVs. Same Dicor sealants work.
Winterize: The process of draining or filling the water system with RV antifreeze before freezing weather, to prevent burst pipes.

Safety

Carbon monoxide detector: Required CO sensor that alarms if combustion gases enter the cabin. Often combined with the propane detector. Replace every 5-7 years.
GFCI: Ground Fault Circuit Interrupter outlet. Required in wet areas. If tripped, can disable the water heater electric element and other circuits in the rig.

Service

Mobile RV tech: An independent RV repair tech who comes to your campsite or driveway. Faster and often cheaper than dropping off at a dealer. Networks: NRVTA, Mobile RV Service Network.

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