Finding the data plate
Where the rating plate (data plate, nameplate) usually sits on each product type, and what to copy from it.
The plate carries the model number, the serial number, electrical ratings and, on gas and water equipment, the standard the unit was certified against (an ANSI or CSA line with a year). Copy the serial exactly as printed, including letters and any hyphens; the decoder normalizes spaces and hyphens itself.
Central Air Conditioner
On the outdoor condenser: a metal or foil plate on the side or back of the cabinet, often near the refrigerant line connections. Some brands repeat it inside the electrical access panel.
Decoders: Aire-Flo, AirEase, Airquest, Allied Air, Amana HVAC, American Standard, Ameristar, Arcoaire, Armstrong Air, Broan HVAC, Bryant, Carrier, Champion, Coleman
Heat Pump
On the outdoor unit, same place as a condenser: a plate on the side or back of the cabinet near the line set. The indoor air handler carries its own plate with its own serial.
Decoders: Aire-Flo, AirEase, Airquest, Allied Air, Amana HVAC, American Standard, Ameristar, Arcoaire, Armstrong Air, Bard, Bosch (HVAC), Broan HVAC, Bryant, Carrier
Furnace
Inside the furnace: remove the upper (burner) access door and look on the inside of the door, on the blower compartment wall, or on a sticker facing you at the burner deck.
Decoders: Aire-Flo, AirEase, Airquest, Allied Air, Amana HVAC, American Standard, Ameristar, Arcoaire, Armstrong Air, Bard, Broan HVAC, Bryant, Carrier, Champion
Boiler
On the jacket: a plate or sticker on the front or side of the boiler casing, sometimes behind a removable front panel next to the gas valve or control.
Decoders: Bosch (HVAC), Bradford White, Buderus, Burnham / U.S. Boiler, Crown, Dunkirk, Energy Kinetics, HTP, IBC, Laars, Navien, New Yorker, Peerless, Rinnai
Mini Split
Two plates: one on the side of the outdoor unit, one on the indoor head (lift the front cover or look under the unit). The two serials differ; decode the outdoor unit for the system age.
Decoders: Daikin, Fujitsu, Gree, Hisense, LG, Midea, Mitsubishi Electric, Mitsubishi Electric Trane, MrCool, Panasonic, Pioneer, Samsung, Senville
Packaged Unit
On the cabinet exterior near the electrical access panel, or inside the panel door.
Decoders: AAON, Airquest, Amana HVAC, American Standard, Ameristar, Arcoaire, Bryant, Carrier, Comfortmaker, Daikin, Day & Night, Goodman, Heil, KeepRite
PTAC
Slide the chassis out of its wall sleeve or lift the front cover: the plate is on the chassis frame or on the side of the unit.
Decoders: Amana PTAC, GE Zoneline, Hisense, Panasonic, Sharp
Water Heater
The rating plate is a large label on the side of the tank near the top or beside the control. The serial is printed on it, often beside the model number and the ANSI standard line.
Decoders: A.O. Smith, American Water Heater, Ariston, Bradford White, GE Water Heaters, GE/GeoSpring, GSW, HTP, John Wood, Kenmore Water Heaters, Laars, Lochinvar, Reliance, Rheem
Tankless Water Heater
On the side or bottom of the wall-hung cabinet, or inside the front cover on the frame.
Decoders: A.O. Smith, American Water Heater, Bosch (HVAC), Bosch Water Heaters, Bradford White, Navien, Noritz, Rheem, Richmond, Rinnai, Ruud, Ruud Water Heaters, State, Stiebel Eltron
Heat Pump Water Heater
On the tank side like a conventional heater, usually below the compressor housing.
Decoders: A.O. Smith
Generator
Standby units: a plate inside the enclosure or on the frame near the controller. Portables: a sticker on the frame or engine housing.
Decoders: Briggs & Stratton, Centurion, Cummins/Onan, Generac, Honda, Kohler, Westinghouse Generators
Refrigerator
Inside the fresh-food compartment: on a side wall, the ceiling, or behind the crisper drawers.
Decoders: Admiral, Amana Appliances, Beko, Bertazzoni, Blomberg, Cafe, Dacor, Danby, Electrolux, Estate, Fisher & Paykel, Frigidaire, Gaggenau, GE Appliances
Range
Open the oven door or the storage drawer and look on the frame; slide-in ranges often carry it under the cooktop lip.
Decoders: Admiral, Amana Appliances, Beko, Bertazzoni, Blomberg, Cafe, Dacor, Danby, Electrolux, Estate, Fisher & Paykel, Frigidaire, Gaggenau, GE Appliances
Dishwasher
Open the door: the label is on the inner door edge or the side of the tub frame.
Decoders: Admiral, Amana Appliances, Asko, Beko, Bertazzoni, Blomberg, Cafe, Dacor, Danby, Electrolux, Estate, Fisher & Paykel, Frigidaire, Gaggenau
Washer
Inside the lid or door rim, on the back panel, or behind the detergent drawer on front-loaders.
Decoders: Admiral, Amana Appliances, Asko, Beko, Blomberg, Cafe, Danby, Electrolux, Estate, Fisher & Paykel, Frigidaire, Gaggenau, GE Appliances, Haier
Dryer
Inside the door opening on the frame, or on the back panel.
Decoders: Admiral, Amana Appliances, Asko, Beko, Blomberg, Cafe, Danby, Electrolux, Estate, Fisher & Paykel, Frigidaire, Gaggenau, GE Appliances, Haier
Microwave
Inside the door on the frame, or on the back or side of the cabinet.
Decoders: Admiral, Amana Appliances, Beko, Blomberg, Cafe, Dacor, Danby, Electrolux, Estate, Fisher & Paykel, Frigidaire, Gaggenau, GE Appliances, Haier
General guidance from common plate placements, not brand-specific; the owner's manual is definitive.