Lennox Furnace: EL296UHV: normal gas heat sequence (what should happen after a call for heat)
EL296UHV: normal gas heat sequence (what should happen after a call for heat) on a Lennox furnace: Use this to see where a stuck furnace is stopping. Times are from the manual for this series.
Applies to: EL296UHV(X) series
How to fix el296uhv: normal gas heat sequence (what should happen after a call for heat): step by step
- Thermostat calls for heat. The control first checks that both pressure switches are open. If the low one is already closed, it will not start.
- Combustion air inducer starts on low speed.
- Low pressure switch closes, then a 15 second pre-purge runs.
- If the low switch does not close in cold or low voltage conditions, the inducer goes to high speed, runs 10 to 20 seconds, then drops back to low.
- Ignitor warms up for 20 seconds.
- The gas valve opens and a 4 second light-off attempt begins. The ignitor stays powered until flame is proven.
- No flame: the control tries again up to four more times with a 35 second purge and warm-up in between (five tries total).
- After five failed tries the control locks out (flame failure watchguard) and tries again after 60 minutes.
- Blower starts 30 seconds after the burners light (fixed). It stops after the heat blower-off delay set on DIP switches 3 and 4 (default 90 seconds).
- With a single-stage thermostat the furnace lights on low and moves to high after the SW2 delay (7 or 12 minutes). If both stages are called together it lights on low and moves to high after 30 seconds.
If the unit shows an error code, look it up: Lennox Furnace codes
Models
Lennox EL195UHNE
EL195UH040NE36BEL195UH060NE36BEL195UH080NE48CEL195UH100NE60C
EL296UHV
EL296UH045XV36BEL296UH070XV36BEL296UH090XV36CEL296UH090XV48CEL296UH090XV60CEL296UH110XV48CEL296UH110XV60CEL296UH135XV60D
Lennox ML180UHE
ML180UH045E36AKML180UH045XE36AKML180UH070E36AKML180UH070E36BKML180UH070XE36AKML180UH070XE36BKML180UH090E48BKML180UH090E60CKML180UH090XE48BKML180UH110E60CKML180UH110XE60CKML180UH135E60DK
Lennox SL280UHV
SL280UH060NV36ASL280UH070V36ASL280UH080NV48BSL280UH080NV60CSL280UH090V36BSL280UH090V48BSL280UH090V60CSL280UH100NV60CSL280UH110V60CSL280UH135V60D
Lennox SL297NV
SL297UH040NV36BSL297UH060NV36BSL297UH080NV48CSL297UH080NV60C
Source: Lennox EL296UHV(X) Unit Information, Corp 1125-L5 (rev. 03/2022), electronic ignition and two-stage operation sections, printed p.28-29. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.