Error Code h
Info Lennox SLP98UHV Error Code h: Variable Capacity Heat Display
TL;DR
Your furnace is operating normally in variable capacity heating mode. The display shows the current heating output level. Disclaimer
This article is for informational purposes only and does not guarantee the accuracy or completeness of the information provided. Always turn off power and gas supply before attempting any repairs. If you smell gas, leave immediately and call your gas company. Consult a licensed HVAC technician for diagnosis and repair. Any actions taken based on this information are at your own risk. What Does Code h Mean?
The "h" display on your Lennox SLP98UHV indicates the furnace is actively running in variable capacity heating mode. This is a normal operating status, not an error code.
The SLP98UHV is a variable capacity furnace that can adjust its heat output from low to high based on demand. When you see this code, it means the thermostat has called for heat and the furnace is responding by modulating its burner output to match your home's heating needs.
No action is required when this code appears. It will change back to idle mode once the thermostat's temperature setpoint is reached.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Diagnostic push button pressed to view variable capacity heat settings | Most common | — |
When to Call a Professional
Contact a licensed HVAC technician if:
- Your furnace displays this code but your home is not getting warm
- The furnace seems to be running constantly without reaching the set temperature
- You hear unusual noises while the furnace is in heating mode
✓ Verified against manufacturer service manual — March 2026