Lennox SLP98UHV Error Code H: Heat Stage Display
What Does Code H Mean?
The uppercase letter H on the Lennox SLP98UHV display indicates the heat stage diagnostic readout. This appears when cycling through the diagnostic menu using the push button on the control board. The display shows the heating stage number (1 or 2) followed by the CFM setting for that stage.
While the SLP98UHV is a variable-capacity furnace that modulates its output, it also has discrete stage settings that define the operating boundaries. Stage 1 represents the lower range of heating output used for moderate heating demands, and Stage 2 represents the higher range for cold weather. The blower speed is matched to each stage to maintain proper airflow across the heat exchanger.
This is an informational display only and requires no action. Technicians use this readout to verify the heating stage configuration is correct for the installed system. The display will continue cycling through other diagnostic items or return to the idle state.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Diagnostic push button pressed to view heat stage settings | Most common | — |
When to Call a Professional
Contact a licensed HVAC technician if:
- You suspect the heating stages or blower speeds are not configured correctly
✓ Verified against manufacturer service manual — March 2026