OEM Lennox Camstat Limit Control 3in (Supco L593BA) — Y8851
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The Lennox Y8851 is a genuine OEM Camstat limit control (Supco L593BA equivalent) with a 3-inch sensing element. It serves as the high-limit safety switch in your Lennox furnace, monitoring plenum temperature and cutting power to the burners if the heat exchanger area gets dangerously hot. This protects the heat exchanger from cracking and prevents unsafe overheating.
Common failure symptoms: When the Y8851 fails, the furnace may repeatedly trip on limit and lock out, shut down mid-cycle, fail to fire at all, or overheat because the safety no longer opens. A stuck-closed switch is especially dangerous, while a stuck-open switch leaves you with no heat.
Why OEM matters: The trip temperature and 3-inch probe length are matched to your Lennox heat exchanger geometry. Installing the factory-spec Y8851 ensures the limit opens at exactly the rated setpoint for proper safety protection and a correct mechanical fit. Generic limits with the wrong length or setpoint can nuisance-trip or fail to protect the furnace. Always use genuine OEM for critical safety components.
Shipping Information
- Orders placed before 3PM CST ship same business day
- Standard delivery: 2-5 business days
- Express shipping available at checkout
- Free shipping on orders over $75
- Tracking number emailed upon shipment
Return Policy
- 30-day returns on unused parts in original packaging
- Electrical parts (capacitors, contactors, control boards) are final sale once installed
- Email info@nationalhvacparts.com to initiate a return
- Refunds processed within 5-7 business days