FieldBench

Bryant

800S

Furnace · Legacy / Preferred 80% · single-stage · metal vent

Bryant 80% single-stage. 800S / 801S / 810S are Legacy multi-18-speed; 820S / 821S are Preferred VS 80% with InteliSense. Category I metal vent on all of them. Two-digit 31 is chimney/inducer, never a 96% trap. 801S / 811S / 821S are the Low-NOx badges — same draft physics.

Not 880TA Evolution two-stage 80% (ABCD). Not 916S / 926T condensing. If you see a PVC collector, you are on the wrong plate.

Walk this in Diagnose

This plate

AFUE
80% · Category I metal vent
Staging
Single-stage gas · one draft switch
Blower
800S family: multi-18-speed. 820S family: Preferred VS + InteliSense
Control
Two-digit 24V IFC

This board

Two-digit IFC · 80% single-stage

  • 11–14, 21–24, 31, 33, 34. Same Comfort 80 language as Carrier 58STA.
  • No 58/59 condensate pair. If you see those numbers you are on a 96% or a Rheem.
  • 820S adds VS / InteliSense — 41/44 can appear. 31 is still metal-vent draft.

Sequence

  1. W. Inducer → metal-vent prove → HSI → valve → flame → blower. Chimney and common vent matter.

Faults on this IFC

  • 13 / 33

    Limit

    warn

    Airflow. 80% coil on top is still a dirty A-coil.

    • Filter, heat speed / VS setup, coil.
  • 14 / 34

    Ignition

    lockout

    HSI / gas / rod.

    • Fix 31 draft before a fair 34 test.
  • 31

    Draft / PS

    lockout

    Metal vent will not prove.

    • Cap, liner, common vent, inducer wheel. Not a PVC trap.
  • 41 / 44

    Blower (820S VS)

    lockout

    Preferred VS 80% only.

    • If this is an 800S 18-speed, 41 is the wrong card — confirm the plate.

Workflows

31 on 800S / 820S

Do not dump a condensate trap.

  1. Metal vent, no collector. Look at the chimney and the inducer.
  2. Then the PS hose on the inducer housing.
  3. 820S vs 800S is the blower, not the draft physics.

Test points

Vent
Cat I. Spillage is a fail.

Gotchas

  • Carrier 58STA is the Comfort 80 language twin.
  • 830SA Ultra-Low NOx is still 80% metal vent — same 31, different burner.

Related plates

  • carrier-58sta — Carrier Comfort 80 single-stage parent language.
  • bryant-880ta — Evolution two-stage 80%. Same metal vent, ABCD bus this Legacy board does not have.
  • bryant-916s — Legacy 96%. Same 31 number, PVC trap instead of a chimney.