HVAC Limit Controls

Surplus City Liquidators sources surplus limit switches for HVAC directly from manufacturers as overstock. These are brand-new, never installed components from overproduction runs, discontinued model lots, or excess inventory buyouts. These are the same discount furnace limit controls available through a traditional HVAC distributor, arriving in manufacturer or protective packaging where available. "Surplus" describes the sourcing channel, not the condition of the part.

The collection includes high limit switches in snap disc limit switch (1" disc) and disc-type configurations, auxiliary limit switch HVAC models, and thermostat limit switches covering trip temperatures from approximately 95°F through 210°F. Both automatic reset and manual reset types are available, along with fixed setpoint and adjustable setpoint models. Terminal configurations of 2 and 3 are represented, with 2-hole mounting standard on snap disc types. Inventory rotates based on manufacturer overstock availability, so checking current listings for available trip temperatures and reset types before ordering is recommended.

The four critical match points are trip temperature (the setpoint at which the switch opens and interrupts the circuit), reset temperature (the setpoint at which it closes again), temperature differential between the two, and reset type (auto or manual). Terminal count and mounting configuration also need to match. A 2-terminal and a 3-terminal switch are wired differently, and the mounting hole pattern must align with the furnace plenum or heat exchanger bracket. The original switch's L-series designation, such as L210-30F, L180-40F, or L95-10F, encodes trip temperature and differential and is the most direct cross-reference for finding a compatible replacement.

An HVAC limit switch auto reset manual reset distinction matters because the two types are not interchangeable in most applications. An auto reset switch restores the circuit automatically once the temperature drops back below the reset setpoint, which is a standard for most residential high limit and fan limit positions. A manual reset switch requires a technician to press a reset button before the circuit can close again, and is used where an automatic restart after a safety trip would be unsafe without human verification, such as auxiliary rollout limits. Installing the wrong reset type creates either a nuisance service call or a unit that will not restart after a routine temperature event, so matching the original specification is essential.

Many surplus HVAC safety controls in this collection are cross-brand compatible. A snap disc switch with the correct trip temperature, differential, terminal count, and mounting will function in most furnace applications regardless of the original OEM brand, because L-series designations are an industry-standard rating system used across manufacturers. Cross-referencing the L-series designation from the original switch against product listings is typically sufficient to confirm a compatible replacement; alternate part numbers are listed where confirmed. When a furnace requires a switch integrated into a proprietary limit and fan control assembly, OEM sourcing may be necessary. Verify the original switch type before ordering.

A limit switch that trips once due to a correctable airflow condition, such as a clogged filter or blocked return, and resets cleanly once that condition is resolved is not necessarily at end of life. A switch that trips repeatedly, fails to reset at room temperature, or shows open continuity when cool on a multimeter has typically failed and needs a furnace high limit switch replacement. Disc-type switches wear out from repeated thermal cycling and may no longer snap reliably between open and closed states. Replacement requires matching trip temperature, differential, reset type, terminal count, and mounting to the original. An incorrect replacement can cause nuisance trips or, more critically, failure to open when the circuit needs to be interrupted.

Limit switches are small, lightweight components that ship via standard ground to all 48 contiguous states without freight-class complications. Shipping charges are calculated at checkout based on package dimensions, weight, and carrier fuel surcharges. Check online for pickup availability at our various locations.