FieldBench

Lennox

SL280

Furnace · Elite · two-stage · 80% · metal vent

Elite 80% two-stage (SL280UHV / EL280). Category I metal vent. VS SKUs may show the same SureLight 7-seg E2xx family as EL296V — if you see E223 it is still metal-vent draft, not a PVC trap. Flash SKUs use Merit-like 1–9 flashes. Identify the display and the vent before you cut anything.

Not EL296V (96% PVC collector and trap — same E223 number, opposite wet/dry checks). Not ML180 (Merit flash, single-stage; same 80% vent, different board and staging).

Walk this in Diagnose

This plate

AFUE
80% two-stage · Category I metal vent
Display
VS SKUs: SureLight 7-seg E2xx. Other SKUs: Merit-like 1–9 flash
Staging
Two-stage valve · two-speed inducer
Sister SKU
SL280UHV · EL280 / EL280UH

This board

SureLight 7-seg or Merit LED — read the door

  • First minute: 7-seg E-prefix or flashing LED? VS 80% SKUs speak E2xx. Flash SKUs speak 1–9 like ML180.
  • E223 / E225 / E229 on this plate are metal-vent draft. Do not prime a 96% trap that is not there.
  • 3-flash on a flash SKU is the same metal-vent story as ML180, with a second stage in play.
  • Confirm any odd extra code on THAT door card.

Sequence

  1. W1. Low inducer → low PS (E223 or 3-flash if metal-vent draft will not make) → HSI → low-fire valve → flame.
  2. W2. High inducer → high PS (E225). Common-vent / chimney load shows up here first on cold days.

Faults on this IFC

  • E223 / 3-flash

    Low PS open / draft

    lockout

    Low-fire prove failed. On this 80% that is chimney, inducer, common vent — not a drowned 96% trap.

    • Metal vent, liner, common-vent sizing, inducer wheel, burner-box intake.
    • If the display is E223 you are on a SureLight VS SKU. Same number as EL296V, opposite vent physics.
  • E225

    High PS failed OPEN

    lockout

    High-fire prove failed. Chimney that passed on low will fail on high.

    • Inducer actually high? Common vent / wind / liner. High hose not teed to the low switch.
  • E229

    Ignition on high fire

    info

    Low prove failed; IFC lit on high. OEM: fix low-fire draft, not a separate high-fire repair.

    • Same metal-vent path as E223. Do not start on the high-fire manifold screw.
  • E250 / 4-flash

    Limit

    warn

    Airflow / overtemp. 5-flash on a flash SKU is still rollout.

    • VS heat CFM or heat tap, filter, coil. Rollout: exchanger and metal flue.
  • E270 / 7-flash

    Ignition lockout

    lockout

    Max retries, no flame current (7-seg) or ignition lockout (flash).

    • Watch a try. HSI, gas, rod. If E271 / 6-flash stores, draft died — go back to the vent.
  • E207 / E290

    HSI / ignitor circuit

    lockout

    Ignitor open or trigger fault (7-seg SKUs).

    • Ohms and 120 VAC during trial.

Workflows

Identify 80% vs 96% before cutting a trap

E223 or 3-flash, first minute on an Elite / Merit Lennox.

  1. Plate: SL280 / EL280 / ML180 = 80% metal vent. EL296 / ML196 = 96% PVC.
  2. E223 on metal vent is chimney / inducer / common vent. E223 on EL296V is trap / PVC / inducer port.
  3. 3-flash on SL280 flash SKUs is the ML180 story, not the ML196 story.
  4. Do not install a condensing trap on an 80%. Do not chase a chimney liner on a 96%.

Test points

Vent
Metal Category I. Draft at the hood / collector.
Display
E-prefix = SureLight VS SKU. Flashes = Merit-like SKU. Same 80% physics either way.
LPS / HPS
Two-stage = two proves. High fire loads the chimney harder.

Gotchas

  • EL296V techs see E223 and cut a trap. There is no 96% collector on this furnace.
  • ML180 is the single-stage Merit 80% with flashes only. This Elite can be 7-seg or flash — read the door.
  • EL280 is the same Elite 80% family under the older badge.

Related plates

  • lennox-el296v — Elite 96% VS. Same SureLight E2xx numbers on VS SKUs — PVC trap physics, not metal vent.
  • lennox-ml180 — Merit 80% single-stage flash. Same metal-vent 3-flash physics, no two-stage / no 7-seg.