FieldBench
York codes

York

8 red

Lockout

Flame lost 5 times

Flame dropped after prove.

Walk 8 red in Diagnose

5 plates — walk the one on the cabinet

First check

1 Measure µA while it is running

Do not clean first and guess. Series-µA the rod on York TM8T during a call. Falling µA is oxide, ground, or a dying flame. A hard drop is often the pressure switch or limit opening, not the rod. µA, gas, draft when the blower starts.

Expect: Flame sense: Normal ~3.7 µA DC. Warning < 1.5 µA. Lockout < 0.1 µA.

The rest of the walkthrough is Diagnose.

On the plates

  • µA while running — want ~3.7 µA, warning <1.5, drop-out <0.1.
  • Gas pressure sag when other appliances fire. Valve that will not hold.
  • Draft that collapses when the blower comes on (limit/PS cluster).
  • µA, gas sag, draft collapse when the blower starts on that heat tap.
  • µA, gas, draft when the blower starts.

Plates that use 8 red