House - Furnace Parts [Lifetime Warranty] L210-20F Furnace Primary Limit Switch -40°F to 180°F
L210-20F furnace primary limit switch with metal mounting flange and two electrical terminals.
L210-20F furnace primary limit switch showing dimensions and technical specifications.
L210-20F furnace primary limit switch with temperature rating of -40°F to 180°F shown on promotional graphic.
Close-up detail views of the L210-20F furnace primary limit switch showing aluminum and thermoplastic construction.
L210-20F furnace primary limit switch compatibility chart showing two angles of the replacement part.
Compatibility chart for L210-20F furnace primary limit switch listing compatible ICP, Heil, and Tempstar furnace models.
L210-20F furnace primary limit switch shown with technician repairing furnace and list of common repair symptoms.
Four-step installation guide for L210-20F furnace primary limit switch showing removal, testing, and replacement.
L210-20F furnace primary limit switch with metal mounting flange and electrical terminals.
L210-20F furnace primary limit switch with metal mounting flange and two electrical terminals.
L210-20F furnace primary limit switch showing dimensions and technical specifications.
L210-20F furnace primary limit switch with temperature rating of -40°F to 180°F shown on promotional graphic.
Close-up detail views of the L210-20F furnace primary limit switch showing aluminum and thermoplastic construction.
L210-20F furnace primary limit switch compatibility chart showing two angles of the replacement part.
Compatibility chart for L210-20F furnace primary limit switch listing compatible ICP, Heil, and Tempstar furnace models.
L210-20F furnace primary limit switch shown with technician repairing furnace and list of common repair symptoms.
Four-step installation guide for L210-20F furnace primary limit switch showing removal, testing, and replacement.
L210-20F furnace primary limit switch with metal mounting flange and electrical terminals.
Lifetime Warranty

[Lifetime Warranty] L210-20F Furnace Primary Limit Switch -40°F to 180°F

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L210-20F Furnace Primary Limit Switch -40°F to 180°F

Key Features

  • High-temperature limit control with automatic reset
  • Opens circuit at 210°F (99°C)
  • Closes circuit at 190°F (88°C)
  • Differential: 20°F
  • Switch Action: Single Pole, Single Throw (SPST), normally closed
  • Insertion Length: 3 inches

Replaces / Cross-Reference Part Numbers

  • Rheem-Ruud: 47-25349-06
  • Nortek / Nordyne: 41835, 626565

Compatibility & Fitment

  • Designed for use as a primary high-limit switch in forced-air gas or electric furnaces.
  • Fits specific furnace models from brands including Rheem, Ruud, and Nortek (Nordyne).
  • Verify fitment by comparing the part number and temperature ratings (L210-20F) with the original switch.

When to Replace

  • Furnace cycles on and off more frequently than normal (short-cycling).
  • The main blower motor runs continuously after the heating cycle completes.
  • The furnace fails to ignite or produce heat due to an open limit circuit.
  • The switch fails a continuity test with a multimeter when at room temperature.
  • Visible signs of damage, such as corrosion, burnt terminals, or a cracked casing.

Installation Tips

  • Disconnect all electrical power to the furnace unit before beginning any service.
  • Confirm the temperature ratings on the replacement switch match the original component exactly.
  • Handle the new switch by its mounting plate to avoid damaging the sensor element.
  • Ensure all wire terminal connections are clean, tight, and secure.
  • After installation, run a full heating cycle to confirm the furnace and blower operate correctly.

FAQ

This switch is commonly associated with several furnace brands depending on the specific part number and mounting style. Confirm fit by matching both the L210-20F rating and your original part number. Reported compatible brand groups include Nordyne, Intertherm, Miller, and Tappan, as well as ICP, Heil, Tempstar, Carrier, Day & Night, Keeprite, Comfortmaker, Arcoaire, and Sears.
Known cross-reference numbers for this switch family include 626425, 313408, 34335001, 34335-001, HQ34335001TD, and 338085-758. Always verify the temperature rating, terminal layout, probe length, and mounting style against your original switch before ordering.
L210-20F indicates the switch opens on temperature rise at 210°F. The “-20F” portion refers to the differential, meaning the switch typically resets after the temperature drops by about 20°F. This type of primary limit switch is a safety device that helps shut off the burner if the furnace overheats.
Common symptoms include the burners shutting off before the heating cycle finishes, the blower running excessively, the furnace starting and stopping repeatedly, lockout codes related to open limit, or no heat after an overheating event. Keep in mind that a limit switch may be reacting normally to an airflow or venting problem, so the switch itself is not always the root cause.
Repeated trips are often caused by overheating from restricted airflow rather than a defective switch. Common causes include a clogged air filter, dirty evaporator coil, blocked supply or return vents, blower wheel buildup, weak blower motor performance, or improper gas input. A limit switch can also weaken over time after repeated heat cycles, but it is important to correct the overheating condition before replacing it.
Replacement is usually straightforward for someone familiar with furnace service. Typical steps are shutting off power, removing the access panel, labeling and disconnecting the wires, removing the mounting screws, swapping the switch, and reinstalling the wires. Basic tools are usually a screwdriver and possibly a nut driver. The job often takes about 15 to 30 minutes, but exact access depends on the furnace design.
Before installation, compare the original switch carefully for the same temperature rating, terminal configuration, insertion length, and mounting dimensions. Also inspect the furnace for the reason the old switch opened: check the air filter, blower operation, duct restrictions, indoor coil cleanliness, and venting path. Replacing the switch without fixing an overheating problem can lead to repeat shutdowns.