SUPCO
SUPCO SHL502 Gas Limit Thermostat L180-30F 180-150F
Protects gas furnaces by opening at 180°F and resetting at 150°F, replacing Goodman, Carrier and Lennox OEM parts
- Opens at 180°F to prevent overheating
- Resets automatically at 150°F after cool-down
- 30°F differential protects heat exchanger
- Direct replacement for Goodman Carrier Lennox
- Compact design fits existing furnace brackets
SUPCO SHL502 Gas Limit Thermostat
The SUPCO SHL502 is a brand-new gas limit thermostat rated L180-30F for residential and light commercial gas furnaces. It opens at 180°F and resets at 150°F with a 30°F differential to protect the heat exchanger from overheating. The compact design allows direct replacement of several OEM part numbers including B137001, HH12ZA178A, 26H6501 and L39-180. It fits compatible Goodman, Carrier and Lennox models.
Practical limits of the L180-30F rating
This high-limit switch operates on a fixed 180°F opening and 150°F reset cycle with a 30°F differential that cannot be adjusted in the field. It is designed solely as a safety cutoff for gas furnace heat exchangers and plenums, not as a primary temperature controller. The bi-metal mechanism responds to local plenum temperature, so airflow restrictions or dirty filters can cause nuisance trips before the set point is reached. Continuous cycling at the limit indicates an underlying airflow or sizing issue that the thermostat cannot correct.
Check your furnace before ordering
Confirm the existing limit thermostat carries the L180-30F rating or an exact OEM cross-reference such as B137001, HH12ZA178A, 26H6501 or L39-180. Verify the mounting bracket and terminal orientation match the furnace heat exchanger or plenum location shown in the service manual. Ensure the gas furnace brand is listed among compatible Goodman, Carrier or Lennox models before installation. Disconnect power and shut off the gas supply before removing the old switch.
Highlights
- Opens at 180°F to prevent overheating
- Resets automatically at 150°F after cool-down
- 30°F differential protects heat exchanger
- Direct replacement for Goodman Carrier Lennox
- Compact design fits existing furnace brackets
Specifications
| Brand | SUPCO |
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Questions about this item
Which temperature range should I select for my furnace?
Choose the L180-30F version that opens at 180°F and resets at 150°F, a 30°F differential specified for this SHL502 limit thermostat.
What does the L180-30F rating mean when the switch is installed?
It means the contacts open to shut off the burner at 180°F and automatically close again once the heat exchanger cools to 150°F.
What mounting standard does this limit thermostat use?
It mounts with screws to the furnace heat exchanger or plenum and connects via standard wire terminals for direct OEM replacement.
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