Glossary
Home repair terms, in plain English.
61 terms across HVAC, plumbing, electrical, appliances and how membership coverage works. Each one starts with a definition you can quote, then why it matters to you.
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- Membership & Coverage Add-On Coverage Add-on coverage is optional protection bought on top of a base home repair plan for equipment the base plan leaves out, such as a well pump, septic system, pool equipment, or a second refrigerator. Each add-on carries its own price and is covered only when the homeowner elects it at enrollment or later.
- Electrical AFCI Breaker An AFCI breaker is a circuit breaker with a built-in arc-fault circuit interrupter that monitors the current waveform for the signature of dangerous arcing, such as from a damaged cord, a loose connection, or a nail through a wire, and trips before the arc can start a fire. The NEC requires AFCI protection on most living-area circuits in new homes.
- Heating & Cooling AFUE AFUE (Annual Fuel Utilization Efficiency) is the U.S. Department of Energy rating for furnace and boiler efficiency: the percentage of fuel energy that becomes usable heat over a typical year. An 80% AFUE gas furnace turns 80 of every 100 units of fuel into heat; condensing furnaces rated 90% or higher recover extra heat from exhaust gases.
- Membership & Coverage Annual Billing Annual billing is a payment option in which a membership or service plan is charged once a year instead of every month. Providers often price the yearly charge below the cost of twelve monthly payments, so the plan holder pays less over the year in exchange for one larger payment up front.
- Plumbing & Water Heating Anode Rod An anode rod is a sacrificial metal rod, usually magnesium, aluminum, or a zinc-aluminum alloy, threaded into the top of a tank water heater. Through galvanic corrosion it corrodes in place of the glass-lined steel tank, so the tank stays protected only while rod material remains. Once the rod is consumed, the tank itself starts to rust.
- Heating & Cooling Auxiliary Heat Auxiliary heat is the backup heat source a heat pump turns on automatically when it cannot meet the thermostat's demand alone, usually electric resistance heat strips in the air handler. It also runs during defrost cycles. Emergency heat is the manual thermostat setting that locks out the heat pump and runs only the backup source.
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- Electrical Ceiling Fan Capacitor A ceiling fan capacitor is a small component in the fan's switch housing that stores and releases electrical charge to create the phase shift a single-phase induction motor needs to start and run at each speed. Rated in microfarads (µF) and volts, a failing capacitor causes slow spinning, humming, a fan that will not start, or missing speeds.
- Electrical Circuit Breaker A circuit breaker is a resettable switch in the electrical panel that automatically cuts power to a branch circuit when current exceeds its rating, such as 15 or 20 amps, or when a short circuit occurs. A thermal element trips on sustained overloads and a magnetic element trips instantly on shorts, protecting the wiring from overheating.
- Heating & Cooling Compressor A compressor is the pump in the outdoor unit of an air conditioner or heat pump that pressurizes refrigerant vapor, raising its temperature so heat can be released outdoors. Most residential systems use scroll compressors; single-stage models always run at full output, while two-stage and inverter-driven variable-speed models adjust output to match the load.
- Air & Ductwork Condensate Drain Line A condensate drain line is the pipe, usually PVC, that carries water from an air conditioner's evaporator coil drain pan, or from a condensing furnace, to a floor drain, the outdoors or a condensate pump. Many systems add a float safety switch that shuts cooling off when the line backs up, protecting ceilings and floors from overflow.
- Air & Ductwork Condenser Coil A condenser coil is the outdoor coil of a central air conditioner, wrapped around the compressor inside the condensing unit. Hot, high-pressure refrigerant releases its heat there as the condenser fan pulls outdoor air across the aluminum fins, and the refrigerant condenses back into a liquid before returning indoors. In a heat pump, this coil also absorbs heat in winter.
- Membership & Coverage Coverage Limit A coverage limit is the maximum amount a home warranty or repair plan will pay toward covered repairs, as written in the plan terms. Costs above the limit are the homeowner's to pay. Limits may be set per system, per item, or per term, so the exact wording matters as much as the dollar figure.
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- Appliances Defrost System (Refrigerator) A refrigerator defrost system is the set of parts in a frost-free refrigerator that periodically melts frost off the freezer's evaporator coil. A timer or control board switches on a defrost heater, a defrost thermostat shuts it off once the coil warms, and the meltwater runs through a drain to a pan under the unit.
- Appliances Dishwasher Drain Pump A dishwasher drain pump is the small electric pump at the bottom of the tub that pushes used wash and rinse water out through the drain hose, into the sink drain or garbage disposal. It runs between wash stages and at the end of the cycle, and many models pair it with a filter or chopper to catch debris.
- Appliances Door Gasket A door gasket is the flexible rubber or vinyl seal around the door of a refrigerator, freezer, dishwasher, or oven that closes the gap between door and cabinet. Refrigerator gaskets contain a magnetic strip that pulls the door tight, keeping cold air in and warm, humid room air out of the cabinet.
- Electrical Doorbell Transformer A doorbell transformer is a small step-down transformer that converts 120-volt household power to the low voltage, usually 10 to 24 volts, that runs a wired doorbell button and chime. It is typically mounted on a junction box near the panel, furnace, or chime, and is rated in volts and volt-amperes (VA), which video doorbells often need more of.
- Plumbing & Water Heating Drain Stoppage A drain stoppage is a blockage in a drain, waste, or sewer line that slows or stops wastewater from leaving a fixture. Common causes include hair, grease, soap scum, wipes, food waste, and tree roots. A stoppage at one fixture usually sits in its trap or branch line, while several backed-up fixtures point to the main line.
- Appliances Dryer Heating Element A dryer heating element is the coil of resistance wire in an electric clothes dryer that heats air before it is pulled through the drum. It runs on a 240-volt circuit and is protected by a high-limit thermostat and a thermal fuse that cut power if the dryer overheats. Gas dryers use a burner instead.
- Appliances Dryer Vent A dryer vent is the duct that carries hot, moist, lint-laden air from a clothes dryer to an exterior wall or roof cap. It runs from the dryer's exhaust outlet through a transition hose and rigid or semi-rigid metal ducting to a hood with a flap that closes when the dryer stops.
E
- Electrical Electrical Panel An electrical panel, also called a service panel or load center, is the metal enclosure where utility power from the meter is divided into branch circuits. It holds the main breaker, which can shut off the whole house, and rows of circuit breakers, each sized to protect one circuit's wiring. Panels carry a UL listing and an amperage rating.
- Appliances ENERGY STAR ENERGY STAR is the U.S. Environmental Protection Agency's voluntary efficiency label for appliances, heating and cooling equipment, and other products. A product earns the blue ENERGY STAR mark through independent testing showing it meets an efficiency specification stricter than the federal minimum standard for its category. Specifications are revised as technology improves.
- Air & Ductwork Evaporator Coil An evaporator coil is the indoor coil of a central air conditioner or heat pump, usually an A-shaped coil above the furnace or inside the air handler. Cold refrigerant in its tubes absorbs heat from household air as the blower pushes air across its fins, and moisture condensing on the coil drips into a drain pan below.
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- Plumbing & Water Heating Faucet Cartridge A faucet cartridge is the replaceable valve body inside a single- or two-handle faucet that controls water flow and, in mixing faucets, the hot and cold blend. Most modern cartridges use ceramic discs or a plastic spool with rubber O-rings, and each brand and model takes a specific part. A worn cartridge causes drips and stiff handles.
- Plumbing & Water Heating Fill Valve A fill valve is the valve inside a toilet tank, usually on the left side, that refills the tank and bowl after each flush and shuts off when its float reaches the set water level. Older brass ballcocks use a float arm, while modern float-cup valves slide on a vertical shaft. A worn fill valve causes running or hissing toilets.
- Heating & Cooling Flame Sensor A flame sensor is a thin metal rod in a gas furnace that sits in the burner flame and confirms ignition using a small electrical current, a process called flame rectification. If the control board does not detect flame within a few seconds of the gas valve opening, it closes the valve and shuts the burners off for safety.
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- Electrical Garage Door Safety Sensors Garage door safety sensors are a pair of photo-eye units mounted on each side of the door opening, usually about six inches above the floor, that send an infrared beam across the doorway. If anything breaks the beam while the door closes, the opener reverses. Under UL 325 and federal rules, residential openers made after 1992 must include entrapment protection.
- Appliances Garbage Disposal A garbage disposal is an electric unit mounted under a kitchen sink that grinds food scraps so they can be flushed down the drain. A motor spins a plate with swiveling impellers that throw food against a stationary grind ring; running water then carries the fine particles out through the trap and drain line.
- Electrical GFCI Outlet A GFCI outlet is a receptacle with a built-in ground-fault circuit interrupter that compares current on the hot and neutral conductors and cuts power within a fraction of a second if about 5 milliamps leak to ground, such as through water or a person. The NEC requires GFCI protection in kitchens, bathrooms, garages, outdoors, and other damp locations.
H
- Heating & Cooling Heat Exchanger A heat exchanger is the sealed metal chamber in a gas furnace where burner flames heat the metal walls while household air passes over the outside. Combustion gases stay inside and leave through the flue, so the exhaust and the air you breathe never mix. Condensing furnaces add a secondary heat exchanger that extracts additional heat from the exhaust.
- Heating & Cooling Heat Pump A heat pump is an electric heating and cooling system that moves heat rather than generating it. In cooling mode it works like a central air conditioner; in heating mode a reversing valve sends refrigerant the other way, extracting heat from outdoor air and releasing it indoors. It typically delivers two to three units of heat per unit of electricity.
- Membership & Coverage Home Repair Membership A home repair membership is a monthly or yearly plan that pays for eligible repairs to listed home systems and appliances, such as HVAC, plumbing, electrical, and major appliances, up to stated limits. The membership arranges the repair visit with a local pro. It is a capped repair plan, not a home warranty and not an insurance policy.
- Membership & Coverage Home Warranty A home warranty is a home service contract, sold for a monthly or yearly price, that pays toward repairing covered home systems and appliances when they fail. Each contract sets its own item limits and exclusions, and the warranty company usually charges a service call fee every time a contractor from its network comes out.
- Heating & Cooling HSPF2 HSPF2 (Heating Seasonal Performance Factor 2) is the U.S. Department of Energy rating for a heat pump's heating efficiency: total seasonal heat delivered in BTUs divided by the watt-hours of electricity used, including defrost and backup heat. It replaced HSPF on January 1, 2023, under a tougher test, so it reads lower for identical equipment.
- Membership & Coverage HVAC Maintenance Plan An HVAC maintenance plan is a service agreement that schedules preventive tune-ups for a home's heating and cooling equipment, typically cleaning, inspection, and adjustment before peak heating or cooling season. It is designed to catch wear early and protect efficiency. A maintenance plan pays for tune-ups, not for repairs when a part fails.
- Heating & Cooling HVAC Tune-Up An HVAC tune-up is a scheduled preventive service visit for a heating or cooling system, usually in spring for cooling and fall for heating. Following checklists such as ACCA Standard 4, a technician cleans or inspects coils, checks refrigerant pressures and capacitors, clears the condensate drain, tests safety controls and inspects gas burners and ignition.
M
- Plumbing & Water Heating Main Water Shutoff Valve A main water shutoff valve is the valve on the main supply line, usually where the line enters the house or beside the water meter, that stops water to the entire home. Most are quarter-turn ball valves or older multi-turn gate valves, and homes on a private well typically have one near the pressure tank.
- Air & Ductwork MERV Rating A MERV rating (Minimum Efficiency Reporting Value) is the ASHRAE Standard 52.2 score, from 1 to 16, for how well an air filter captures airborne particles between 0.3 and 10 microns. Higher numbers trap smaller particles such as fine dust, pet dander and some smoke, but denser filters can restrict airflow in systems not designed for them.
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- Plumbing & Water Heating P-Trap A P-trap is the U-shaped bend of drain pipe under a sink, tub, or shower that holds a small plug of water after every use. That water seal blocks sewer gas from entering the home, while the trap arm connects the fixture to the vented drain system. Plumbing codes require a trap on every fixture drain.
- Membership & Coverage Per-Visit Fee A per-visit fee is the fixed amount charged each time a repair pro comes out under a home warranty or repair plan, separate from the monthly or yearly price. Home warranty companies often call it a service call fee. Because it applies to every visit, it shapes the real cost of using a plan.
- Membership & Coverage Pre-Existing Condition A pre-existing condition is a problem with a home system or appliance that already existed before repair coverage started, whether or not the homeowner knew about it. Home warranties and repair memberships generally exclude these conditions, which is why a newly purchased plan cannot pay for a breakdown that has already happened.
- Plumbing & Water Heating Pressure-Reducing Valve (PRV) A pressure-reducing valve (PRV) is a bell-shaped, spring-loaded valve on the main water line, just after the meter, that lowers incoming municipal pressure to a safe household level, commonly set between 50 and 60 psi. Model plumbing codes such as the IPC and UPC generally require one when static street pressure exceeds 80 psi.
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- Appliances Range Igniter A range igniter is the part that lights the gas in a gas range or oven. Most gas ovens use a hot surface igniter, a glow bar that must draw enough current before the gas safety valve opens. Cooktop burners use spark electrodes that click and spark at the burner when the knob is turned to light.
- Air & Ductwork Refrigerant Refrigerant is the chemical fluid that carries heat through an air conditioner or heat pump, absorbing heat as it evaporates in the indoor coil and releasing it as it condenses outdoors. Under EPA rules issued through the AIM Act, new residential systems are moving from R-410A to lower global-warming-potential refrigerants such as R-454B and R-32.
- Heating & Cooling Run Capacitor A run capacitor is an electrical component that stores and releases energy to keep the compressor and fan motors in an air conditioner or heat pump running efficiently. It is rated in microfarads (µF), and many outdoor units use one dual run capacitor serving both motors. A separate start capacitor, when fitted, gives the compressor a brief startup boost.
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- Plumbing & Water Heating Sediment Buildup Sediment buildup is the layer of calcium carbonate, magnesium, and other minerals that settles out of heated water onto the bottom of a tank water heater. The layer insulates the water from a gas burner or buries the lower electric element, causing popping or rumbling noises, slower recovery, reduced capacity, and overheating of the tank floor.
- Heating & Cooling SEER2 SEER2 (Seasonal Energy Efficiency Ratio 2) is the U.S. Department of Energy rating for the cooling efficiency of central air conditioners and heat pumps: total seasonal cooling in BTUs divided by the watt-hours of electricity used. It replaced SEER on January 1, 2023, under a test with higher duct resistance, so it reads lower for identical equipment.
- Plumbing & Water Heating Septic Tank A septic tank is a buried, watertight tank of concrete, fiberglass, or polyethylene that receives all household wastewater on properties without a sewer connection. Solids settle as sludge, grease floats as scum, and the clarified effluent flows through an outlet baffle and filter to a drain field, where soil completes treatment. EPA guidance calls for regular inspection and pumping.
- Membership & Coverage Service Request (Claim) A service request, often called a claim, is a member's formal request for a repair under a home repair plan or home warranty. It records which system or appliance failed and the symptoms, is reviewed for eligibility under the plan terms, and, once accepted, leads to a scheduled visit from a repair pro.
- Electrical Service Size (Amperage) Service size is the maximum current, in amperes, that a home's electrical service can deliver from the utility, set by the service conductors, meter base, and main breaker. Common residential sizes are 100, 150, and 200 amps, and an NEC Article 220 load calculation determines how much connected equipment a given service can support.
- Heating & Cooling Short Cycling Short cycling is when a furnace, air conditioner or heat pump turns on and off in rapid cycles, running only a few minutes before shutting down without completing a normal heating or cooling cycle. Common causes include an oversized system, a clogged air filter, low refrigerant, a furnace overheating and tripping its limit switch, or a poorly placed thermostat.
- Heating & Cooling Smart Thermostat A smart thermostat is a Wi-Fi-connected thermostat that controls a heating and cooling system through schedules, occupancy sensing, geofencing and a smartphone app. Many models learn household routines and report runtime and maintenance alerts, and ENERGY STAR recognizes models meeting its smart thermostat criteria. Most need a common wire, or C-wire, for steady power.
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- Plumbing & Water Heating T&P Relief Valve A T&P relief valve, short for temperature and pressure relief valve, is a spring-loaded safety device on a water heater that opens automatically if tank water reaches about 210°F or pressure reaches about 150 psi. Required by plumbing codes and built to the ANSI Z21.22 standard, it discharges through a pipe to prevent a tank explosion.
- Plumbing & Water Heating Tank Water Heater A tank water heater is a storage appliance that keeps roughly 30 to 80 gallons of water hot inside an insulated steel tank, using a gas burner or electric elements. Cold water enters through a dip tube at the bottom, hot water leaves from the top, and a sacrificial anode rod and T&P relief valve protect the tank.
- Plumbing & Water Heating Tankless Water Heater A tankless water heater is an on-demand appliance that heats water only as it flows, firing a gas burner or electric elements when a flow sensor detects an open tap. With no stored water there is no standby heat loss, so its DOE UEF rating usually beats a comparable tank, but output is limited to a set gallons-per-minute flow.
- Heating & Cooling Tonnage Tonnage is the cooling capacity of an air conditioner or heat pump, where one ton equals 12,000 BTUs (British thermal units) of heat removed per hour. The term comes from the heat needed to melt one ton of ice over a full day. Most homes use systems between 1.5 and 5 tons, sized by an ACCA Manual J load calculation.
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- Membership & Coverage Waiting Period A waiting period is the stretch of time after enrolling in a home warranty or repair plan before the first covered repair request can be filed. Breakdowns that happen during the waiting period are not covered. It keeps a plan from being bought only after something fails, which helps keep pricing fair for every member.
- Appliances Washer Lid Switch (Door Lock) A washer lid switch is the safety switch that tells a washing machine's control the lid is closed before it will spin. Front-load washers use a door lock assembly instead, which latches the door during the cycle. Many newer top-loaders also lock the lid. If either part fails, the washer will not start or spin.
- Plumbing & Water Heating Well Pressure Tank A well pressure tank is a steel tank, usually with an internal rubber bladder or diaphragm, that stores pressurized water from a private well pump. Compressed air on one side pushes water into the house, so the pump does not start whenever a tap opens. A pressure switch typically cycles the pump between settings such as 40 and 60 psi.
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