Hearth and Home Technologies Quadra-Fire 21M-ACC-C vs Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640)
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 76% 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 29,322 BTU/h), suiting roughly 900–1,250 sq ft. The Hearth and Home Technologies Quadra-Fire 21M-ACC-C has the larger firebox (1.48 vs 1.32 cu ft), which generally means longer burns between reloads. Combustion technology differs: the Hearth and Home Technologies Quadra-Fire 21M-ACC-C is a non-catalytic stove and the Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) a hybrid — see the catalytic vs non-catalytic guide for what that means day to day.
| Hearth and Home Technologies Quadra-Fire 21M-ACC-C | Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) | |
|---|---|---|
| Appliance type | wood-stove | wood-stove |
| Combustion technology | Non-Catalytic Stove | Hybrid |
| Certified fuel | Crib Wood | Crib Wood |
| Emission rate | 1.7 g/hr | 1.1 g/hr |
| Efficiency (HHV) | 76 % | 79 % |
| Heat output (low) | 13585 BTU/h | 13876 BTU/h |
| Heat output (high) | 29322 BTU/h | 31581 BTU/h |
| Firebox volume | 1.48 cu ft | 1.32 cu ft |
| Carbon monoxide | 1.5 g/min | 0.52 g/min |
| 25C tax credit eligible (≥75% HHV) | Yes | Yes |
| 2020 NSPS compliant | Yes | Yes |
| Currently in production | Yes | Yes |
| EPA certification number | 250-20 | 210-19 |
| Covered model numbers | Quadra-Fire 21M-ACC-C, Discovery-1-C, FF-WP-100 | Green Mountain 40 Series: Green Mountain 40 (8640), Craftsbury 2 (8392), Hipster 14 (AMB8240) |
Frequently asked questions
Which burns cleaner, the Hearth and Home Technologies Quadra-Fire 21M-ACC-C or the Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640)?
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 Hearth and Home Technologies Quadra-Fire 21M-ACC-C.
Are the Hearth and Home Technologies Quadra-Fire 21M-ACC-C and Hearthstone Quality Home Heating Products Green Mountain 40 Series: Green Mountain 40 (8640) 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.