1. Inngangur
This manual provides essential information for the proper installation, operation, and maintenance of the Lennox 80M51 Limit Switch. Please read this manual thoroughly before attempting any procedures to ensure safe and efficient use of the product. The Lennox 80M51 is a critical component in HVAC systems, designed to monitor and control temperature limits for safe operation.
2. Öryggisupplýsingar
VIÐVÖRUN: Installation and servicing of HVAC components should only be performed by qualified, experienced technicians. Improper installation, adjustment, alteration, service, or maintenance can cause property damage, personal injury, or loss of life.
- Always disconnect power to the unit before installing or servicing the limit switch.
- Notið viðeigandi persónuhlífar (PPE), þar á meðal öryggisgleraugu og hanska.
- Gakktu úr skugga um að allar raflagnir séu öruggar og í samræmi við gildandi rafmagnsreglugerðir.
- Ekki framhjá eða tamper með öryggisbúnaði.
3. Vörulýsing
The Lennox 80M51 is a replacement limit switch designed for use in various Lennox HVAC furnace models. This part is a direct replacement for R20294302 and 80M5101. It is compatible with furnace series including, but not limited to: CMPB050C3B, CMPB075C3B, CMPB100C4B, CMPE050U2B, CMPE050U3B, CMPE075U2B, CMPE075U3B, CMPE100U3B, CMPE100U4B, CMPE125U5B, CMPEV050U3, CMPEV075U3, CMPEV100U4, CMPEV125U5.
A limit switch is a safety device that monitors the temperature within the furnace's heat exchanger. If the temperature exceeds a safe operating limit, the switch will open, interrupting the power to the burner and preventing overheating. This helps protect the furnace from damage and ensures the safety of the occupants.

Image 1: The Lennox 80M51 Limit Switch. This image shows the metallic body of the switch with electrical terminals, designed for integration into HVAC systems.
4. Uppsetning og uppsetning
Installation of the Lennox 80M51 Limit Switch requires careful attention to safety and proper wiring. Consult your furnace's specific service manual for detailed instructions relevant to your model.
- Rafmagnstenging: Turn off all electrical power to the furnace at the main service panel before beginning any work. Verify power is off using a voltage metra.
- Aðgangur: Locate the existing limit switch within the furnace. This typically involves removing an access panel.
- Wiring Disconnection: Carefully disconnect the wires from the old limit switch, noting their positions for correct re-connection. Take a photograph if necessary.
- Fjarlæging: Remove the old limit switch from its mounting bracket.
- Uppsetning nýs rofa: Mount the new Lennox 80M51 Limit Switch in the same location and orientation as the old one.
- Raflagnatenging: Reconnect the wires to the new limit switch according to your notes or photographs. Ensure connections are tight and secure.
- Samsetning aftur: Skiptu um allar aðgangsglugga sem fjarlægðar voru á meðan á ferlinu stóð.
- Rafmagnsendurheimt og prófanir: Restore power to the furnace. Initiate a heating cycle and monitor the furnace's operation to ensure the new limit switch functions correctly.
5. Rekstur
The Lennox 80M51 Limit Switch operates automatically as a safety control. When the furnace is operating, the temperature within the heat exchanger rises. If this temperature exceeds the factory-set limit of the 80M51 switch, the switch will open its electrical contacts, interrupting the circuit to the furnace's burner. This action prevents the furnace from overheating. Once the temperature drops back to a safe level, the switch will automatically reset, allowing the burner to reignite and resume normal operation.
The switch is designed for "Auto" operation, meaning it will automatically reset once conditions return to normal. No manual intervention is typically required for its normal function.
6. Viðhald
The Lennox 80M51 Limit Switch is a sealed component and does not require routine maintenance itself. However, regular maintenance of the overall HVAC system is crucial to ensure the proper functioning of all safety devices, including the limit switch.
- Árleg ofnskoðun: Have a qualified technician inspect your furnace annually. They will check for proper airflow, clean components, and verify the operation of safety controls like the limit switch.
- Skipt um loftsíu: Regularly replace or clean your furnace's air filter as recommended by the furnace manufacturer. A clogged filter can restrict airflow, leading to overheating and frequent tripping of the limit switch.
- Hreinsað loftræstikerfi: Ensure all supply and return air vents in your home are unobstructed to maintain proper airflow.
7. Bilanagreining
If your furnace is frequently cycling off and on, or not heating properly, the limit switch might be involved. Always consult a qualified HVAC technician for diagnosis and repair.
- Tíð ferð: If the limit switch is frequently tripping, it often indicates an underlying issue causing the furnace to overheat, rather than a faulty switch itself. Common causes include:
- Stífluð loftsía.
- Blocked return or supply air vents.
- Malfunctioning blower motor or fan.
- Dirty evaporator coil (if applicable).
- Oversized furnace for the ductwork.
- Ofninn fer ekki í gang: If the furnace does not start at all, and the limit switch is suspected, a technician can test the continuity of the switch. A continuously open switch (even when cool) indicates a fault.
- No Reset: While the 80M51 is an auto-reset switch, if it fails to reset after cooling, it may be faulty and require replacement.
Athugið: Do not attempt to bypass the limit switch. This is a critical safety device, and bypassing it can lead to dangerous operating conditions, including fire hazards.
8. Tæknilýsing
| Vörumerki | Lennox |
| Fyrirmynd | 80M51 |
| Skiptir út hlutanúmerum | R20294302, 80M5101 |
| Notkunarhamur | Sjálfvirk |
| Þyngd hlutar | 4.8 aura |
| Framleiðandi | Bandamanna |
| Tengireglur | X-10 (Note: This might refer to a general control system compatibility, not direct X-10 home automation. Consult a technician for specific application.) |
| Fjöldi eininga | 1 Telja |
| ASIN | B009HEIVBU |
9. Ábyrgð og stuðningur
For warranty information and technical support regarding the Lennox 80M51 Limit Switch, please refer to the official Lennox website or contact your authorized Lennox dealer or service provider. Keep your purchase receipt for warranty claims.
Framleiðandi: Bandamanna
Dagsetning fyrst í boði: 27. júlí 2012





