Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) vs New Buck Corporation (Buck Stove Corp.) 21NC
The Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) is the cleaner burner: 1.1 g/hr certified particulate emissions versus 1.7 g/hr. The Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) is the more efficient unit: 79% versus 70% HHV — more heat from every cord. The Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) produces more peak heat (31,581 vs 28,901 BTU/h), suiting roughly 900–1,250 sq ft. The New Buck Corporation (Buck Stove Corp.) 21NC has the larger firebox (1.4 vs 1.32 cu ft), which generally means longer burns between reloads. Combustion technology differs: the Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) is a hybrid and the New Buck Corporation (Buck Stove Corp.) 21NC a non-catalytic stove — see the catalytic vs non-catalytic guide for what that means day to day.
| Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) | New Buck Corporation (Buck Stove Corp.) 21NC | |
|---|---|---|
| Appliance type | wood-stove | wood-stove |
| Combustion technology | Hybrid | Non-Catalytic Stove |
| Certified fuel | Crib Wood | Crib Wood |
| Emission rate | 1.1 g/hr | 1.7 g/hr |
| Efficiency (HHV) | 79 % | 70 % |
| Heat output (low) | 13876 BTU/h | 11079 BTU/h |
| Heat output (high) | 31581 BTU/h | 28901 BTU/h |
| Firebox volume | 1.32 cu ft | 1.4 cu ft |
| Carbon monoxide | 0.52 g/min | 6.1 g/min |
| 25C tax credit eligible (≥75% HHV) | Yes | No |
| 2020 NSPS compliant | Yes | Yes |
| Currently in production | Yes | Yes |
| EPA certification number | 210-19 | 66-16 |
| Covered model numbers | Green Mountain 40 Series: Green Mountain 40 (8640), Craftsbury 2 (8392), Hipster 14 (AMB8240) | 21NC |
Frequently asked questions
Which burns cleaner, the Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) or the New Buck Corporation (Buck Stove Corp.) 21NC?
The Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640): 1.1 g/hr certified particulate emissions versus 1.7 g/hr for the New Buck Corporation (Buck Stove Corp.) 21NC.
Are the Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) and New Buck Corporation (Buck Stove Corp.) 21NC both EPA certified?
Yes — both appear on the U.S. EPA's current list of certified wood heaters, and every figure on this page comes from their certification records.