Lennox · Series
Lennox Merit ML297 (ML297UH / ML297DF)
The Lennox Merit ML297 is a two-stage condensing gas-furnace family (ML297UH upflow and ML297DF downflow nameplate lines) registered in Canada's NRCan EnerGuide efficiency registry as of 2026-09-09.
Series rating plate
- Family code
- ML297
- Tier
- Merit Series
- Burner
- Two-stage
- Blower
- ECM, variable-speed
- AFUE claim
- Up to 97% AFUE
- Fuel
- Natural gas / Propane
- Positions
- Upflow, Downflow
- Status
- Status unknown · Available in Canada
Merit is Lennox's entry-tier brand line, and the ML297 nameplate families carry the two-stage, variable-speed mechanical package in this catalogue tier. This series record is built from the official Canadian registry listing (export read 2026-09-09): every published ML297 model on this site cites that listing for its capacities and certified efficiency.
ML297UH models cover upflow installations and ML297DF models cover downflow installations, both as condensing furnaces with plastic venting and a condensate drain. Registry AFUE values in this family cluster at 97%. Series-specific installation instructions and control details are added as Lennox literature is verified.
Highlights from the manufacturer's product data
- Two-stage heating, condensing 97% family
- ML297UH (upflow) and ML297DF (downflow) nameplate lines
- Natural gas and propane registry entries (NG/P)
Models in this series
ML297UH045XV36B
Lennox ML297UH045XV36B
Registry-verified ML297UH045XV36B gas furnace: Up to 97% AFUE, listed in Canada's NRCan EnerGuide registry (2026-09-09).
ML297UH070XV36B
Lennox ML297UH070XV36B
Registry-verified ML297UH070XV36B gas furnace: Up to 97% AFUE, listed in Canada's NRCan EnerGuide registry (2026-09-09).
ML297DF070XV48B
Lennox ML297DF070XV48B
Registry-verified ML297DF070XV48B gas furnace: Up to 97% AFUE, listed in Canada's NRCan EnerGuide registry (2026-09-09).
ML297DF090XV60C
Lennox ML297DF090XV60C
Registry-verified ML297DF090XV60C gas furnace: Up to 97% AFUE, listed in Canada's NRCan EnerGuide registry (2026-09-09).
ML297DF110XV60C
Lennox ML297DF110XV60C
Registry-verified ML297DF110XV60C gas furnace: Up to 97% AFUE, listed in Canada's NRCan EnerGuide registry (2026-09-09).
ML297UH090XV36C
Lennox ML297UH090XV36C
Registry-verified ML297UH090XV36C gas furnace: Up to 97% AFUE, listed in Canada's NRCan EnerGuide registry (2026-09-09).
ML297UH090XV60C
Lennox ML297UH090XV60C
Registry-verified ML297UH090XV60C gas furnace: Up to 97% AFUE, listed in Canada's NRCan EnerGuide registry (2026-09-09).
ML297UH110XV60C
Lennox ML297UH110XV60C
Registry-verified ML297UH110XV60C gas furnace: Up to 97% AFUE, listed in Canada's NRCan EnerGuide registry (2026-09-09).
ML297UH135XV60D
Lennox ML297UH135XV60D
Registry-verified ML297UH135XV60D gas furnace: Up to 97% AFUE, listed in Canada's NRCan EnerGuide registry (2026-09-09).
Capacity and width variants documented on this site. Values from the manufacturer's product data; “—” means not published there.
| Size | Input high (BTU/h) | Input low (BTU/h) | Output high (BTU/h) | AFUE upflow (%) | AFUE down/horiz (%) | Width (in) | Page |
|---|---|---|---|---|---|---|---|
| ML297UH045XV36B* | 44,000 | — | 43,000 | 97 | 97 | — | Model page |
| ML297UH070XV36B* | 66,000 | — | 64,000 | 97 | 97 | — | Model page |
| ML297DF070XV48B* | 66,000 | — | 64,000 | — | 97 | — | Model page |
| ML297DF090XV60C* | 88,000 | — | 86,000 | — | 97 | — | Model page |
| ML297DF110XV60C* | 110,000 | — | 108,000 | — | 97 | — | Model page |
| ML297UH090XV36C* | 88,000 | — | 85,000 | 97 | 97 | — | Model page |
| ML297UH090XV60C* | 88,000 | — | 86,000 | 97 | 97 | — | Model page |
| ML297UH110XV60C* | 110,000 | — | 107,000 | 97 | 97 | — | Model page |
| ML297UH135XV60D* | 132,000 | — | 127,000 | 97 | 97 | — | Model page |
Venting
Condensing furnace: plastic (PVC/CPVC) venting per Lennox installation instructions; condensate drainage required.
Factory natural-gas rating; the rating plate states the fuel. Fuel changes on gas appliances belong to licensed technicians using the manufacturer's conversion procedure.
Fault codes for this series
No codes documented yet for this series. See the Lennox index.
Manuals and documents
Questions people ask
Is the Lennox ML297 family sold in Canada?
ML297UH and ML297DF models appear in Canada's official NRCan EnerGuide gas-furnace registry (export read 2026-09-09), which is the evidence used on this page. Confirm current availability with a Lennox dealer.
Talk it through before you decide
A consultation covers sizing, staging, venting and whether a heat pump belongs in the plan. No purchase required.