Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) vs Kuma Stove And Iron Works K-181 Series: Aspen LE-1
Both stoves carry the same certified emission rate: 1.1 g/hr. The Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) is the more efficient unit: 79% versus 78% 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 29,153 BTU/h), suiting roughly 900–1,250 sq ft. The Kuma Stove And Iron Works K-181 Series: Aspen LE-1 has the larger firebox (1.821 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 Kuma Stove And Iron Works K-181 Series: Aspen LE-1 a 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) | Kuma Stove And Iron Works K-181 Series: Aspen LE-1 | |
|---|---|---|
| Appliance type | wood-stove | wood-stove |
| Combustion technology | Hybrid | Catalytic Stove |
| Certified fuel | Crib Wood | Crib Wood |
| Emission rate | 1.1 g/hr | 1.1 g/hr |
| Efficiency (HHV) | 79 % | 78 % |
| Heat output (low) | 13876 BTU/h | 12764 BTU/h |
| Heat output (high) | 31581 BTU/h | 29153 BTU/h |
| Firebox volume | 1.32 cu ft | 1.821 cu ft |
| Carbon monoxide | 0.52 g/min | 0.45 g/min |
| 25C tax credit eligible (≥75% HHV) | Yes | Yes |
| 2020 NSPS compliant | Yes | Yes |
| Currently in production | Yes | Yes |
| EPA certification number | 210-19 | 346-23 |
| Covered model numbers | Green Mountain 40 Series: Green Mountain 40 (8640), Craftsbury 2 (8392), Hipster 14 (AMB8240) | K-181 Series: Aspen LE-1, Tamarack LE-1, Aberdeen LE-1, and Alpine LE-1 |
Frequently asked questions
Which burns cleaner, the Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) or the Kuma Stove And Iron Works K-181 Series: Aspen LE-1?
They are tied: both are certified at 1.1 g/hr of particulates.
Are the Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) and Kuma Stove And Iron Works K-181 Series: Aspen LE-1 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.