Hydronic heaters (the EPA list shoppers call outdoor wood boilers)
EPA lists 165 hydronic-heater rows, and 35 of those rows are currently certified.
Of all hydronic rows, 75 list cord wood, 86 list wood pellets, and 4 list crib wood.
The EPA category is Hydronic Heater. The export does not say outdoor or indoor.
Source: EPA Certified Wood Heater Database, snapshot 2026-10-23.
This page lists hydronic heaters whose certified fuel is not wood pellets. Pellet hydronic rows are on pellet boilers. Forced-air rows are on wood furnaces.
Currently certified
| Model line | EPA manufacturer | Status | Emission (lb/mmBTU) | HHV efficiency | Heat output | Firebox | Fuel |
|---|---|---|---|---|---|---|---|
| Classic Edge 760.1, CleanFire 700.1 | Central Boiler Inc.- WoodMaster Inc. | Currently certified | 0.05 | 83% | 36,488–256,550 BTU/hr | 22.09 cu ft | Cord Wood |
| G Series G10000 | HeatMaster Furnaces, Inc. | Currently certified | 0.05 | 88% | 41,551–280,451 BTU/hr | 23.6 cu ft | Cord Wood |
| Central Boiler Classic Edge 960, WoodMaster CleanFire 900 | Central Boiler Inc.- WoodMaster Inc. | Currently certified | 0.06 | 86% | 47,368–378,339 BTU/hr | 32 cu ft | Cord Wood |
| G Series G7000 | HeatMaster Furnaces, Inc. | Currently certified | 0.06 | 81% | 28,262–195,502 BTU/hr | 16.3 cu ft | Cord Wood |
| Classic Edge 560.1, CleanFire 500.1 | Central Boiler Inc.- WoodMaster Inc. | Currently certified | 0.07 | 83% | 24,564–171,956 BTU/hr | 13.72 cu ft | Cord Wood |
| Classic Edge 865, CleanFire 1800 | Central Boiler Inc.- WoodMaster Inc. | Currently certified | 0.07 | 83% | 33,629–237,755 BTU/hr | 22.68 cu ft | Cord Wood |
| G-Class G2Plus | Polar Furnace Manufacturing Inc. | Currently certified | 0.07 | 81% | 34,835–183,307 BTU/hr | 9.27 cu ft | Cord Wood |
| Crown Royal Stoves 7200E | Greentech Manufacturing Inc. | Currently certified | 0.08 | 77% | 18,091–123,247 BTU/hr | 6.11 cu ft | Cord Wood |
| Crown Royal Stoves 7300E | Greentech Manufacturing Inc. | Currently certified | 0.08 | 75% | 29,773–199,057 BTU/hr | 12.83 cu ft | Cord Wood |
| NEO HV60 | Hargassner GmbH | Currently certified | 0.08 | 70% | 26,340–213,941 BTU/hr | 7.48 cu ft | Cord Wood |
| SE110 | Alternate Heating Systems | Currently certified | 0.08 | 67% | 16,286–121,291 BTU/hr | 5.42 cu ft | Cord Wood |
| S3 Turbo 30 | Fröling Heizkessel und Behälterbau Ges.m.b.H | Currently certified | 0.09 | 77% | 12,997–99,594 BTU/hr | 4.45 cu ft | Cord Wood |
| G Series G4000 | HeatMaster Furnaces, Inc. | Currently certified | 0.1 | 86% | 16,203–99,840 BTU/hr | 8.5 cu ft | Cord Wood |
| SMART HV23 | Hargassner GmbH | Currently certified | 0.11 | 73% | 10,166–78,335 BTU/hr | 3.53 cu ft | Cord Wood |
| Central Boiler Classic Edge 360, WoodMaster– CleanFire 300 | Central Boiler Inc.- WoodMaster Inc. | Currently certified | 0.12 | 82% | 20,293–148,625 BTU/hr | 9.98 cu ft | Cord Wood |
| S3 Turbo 50 | Fröling Heizkessel und Behälterbau Ges.m.b.H | Currently certified | 0.12 | 73% | 24,929–83,097 BTU/hr | 6.78 cu ft | Cord Wood |
| SE210 | Alternate Heating Systems | Currently certified | 0.12 | 71% | 155,802 BTU/hr maximum | 8.43 cu ft | Cord Wood |
Previously certified
| Model line | EPA manufacturer | Status | Emission (lb/mmBTU) | HHV efficiency | Heat output | Firebox | Fuel |
|---|---|---|---|---|---|---|---|
| Blaze HE | Wood Boiler USA | Previously certified | 0 | 58% | 166,109 BTU/hr maximum | Not listed | Cord Wood |
| E4 | Wood Boiler USA | Previously certified | 0 | 61% | 161,455 BTU/hr maximum | Not listed | Cord Wood |
| Pellet Burner Easy 35 | Wood Boiler USA | Previously certified | 0 | 67% | 38,666–429,452 BTU/hr | Not listed | Crib Wood |
| Smart 55 | Effecta Energy Solutions | Previously certified | 0.04 | 83% | 183,573 BTU/hr maximum | Not listed | Cord Wood |
| Vedolux 450 | Varmebaronen AB | Previously certified | 0.04 | 75% | 130,731 BTU/hr maximum | 5.19 cu ft | Cord Wood |
| G Series G10000 | Heatmaster Furnaces Inc. (SteelTech Inc.) | Previously certified | 0.05 | 88% | 41,551–280,451 BTU/hr | 23.6 cu ft | Cord Wood |
| Crown Royal Stoves 7400E | Greentech Manufacturing Inc. | Previously certified | 0.06 | 83% | 43,236–310,495 BTU/hr | 18.44 cu ft | Cord Wood |
| G Class G3 | Polar Furnace Manufacturing Inc. | Previously certified | 0.06 | 77% | 26,235–182,387 BTU/hr | 12.7 cu ft | Cord Wood |
| G Series G7000 | Heatmaster Furnaces Inc. (SteelTech Inc.) | Previously certified | 0.06 | 81% | 28,262–195,502 BTU/hr | 16.3 cu ft | Cord Wood |
| G Series G100/G100s | Steel Tech, Inc. | Previously certified | 0.07 | 68% | 125,000 BTU/hr maximum | Not listed | Cord Wood |
| G Series G200-2/G200s | Steel Tech, Inc. | Previously certified | 0.07 | 75% | 232,000 BTU/hr maximum | Not listed | Cord Wood |
| GARN WHS-2000H | DECTRA (GARN) | Previously certified | 0.07 | 74% | 200,000 BTU/hr maximum | Not listed | Cord Wood |
| GARN WHS-2000V | DECTRA (GARN) | Previously certified | 0.07 | 74% | 200,000 BTU/hr maximum | Not listed | Cord Wood |
| Smart 40 | Effecta Energy Solutions | Previously certified | 0.07 | 75% | 142,600 BTU/hr maximum | Not listed | Cord Wood |
| Woodmaster CleanFire 400 | Northwest Manufacturing Inc | Previously certified | 0.07 | 67% | 102,408 BTU/hr maximum | Not listed | Cord Wood |
| G3-G3 | Polar Furnace Manufacturing Inc. | Previously certified | 0.08 | 72% | 200,000 BTU/hr maximum | Not listed | Cord Wood |
| Vedolux 350 | Varmebaronen AB | Previously certified | 0.08 | 74% | 118,724 BTU/hr maximum | 3.71 cu ft | Cord Wood |
| Vedolux 650 | Varmebaronen AB | Previously certified | 0.08 | 73% | 201,743 BTU/hr maximum | 7.42 cu ft | Cord Wood |
| Central Boiler Classic Edge 760, WoodMaster– CleanFire 700 | Central Boiler Inc.- WoodMaster Inc. | Previously certified | 0.1 | 83% | 34,411–235,938 BTU/hr | 23.2 cu ft | Cord Wood |
| G Series G4000 | Heatmaster Furnaces Inc. (SteelTech Inc.) | Previously certified | 0.1 | 86% | 16,203–99,840 BTU/hr | 8.5 cu ft | Cord Wood |
| Vedolux 37 | Varmebaronen AB | Previously certified | 0.11 | 69% | 132,119 BTU/hr maximum | 3.46 cu ft | Cord Wood |
| Vedolux 55 | Varmebaronen AB | Previously certified | 0.11 | 67% | 170,418 BTU/hr maximum | 5.3 cu ft | Cord Wood |
| CleanFire 300 (Central Boiler Classic Edge 360) | WoodMaster Inc. | Previously certified | 0.12 | 82% | 20,293–148,625 BTU/hr | 9.98 cu ft | Cord Wood |
| Crown Royal RS7200E | Greentech Manufacturing Inc. | Previously certified | 0.13 | 60% | 184,508 BTU/hr maximum | Not listed | Crib Wood |
| Central Boiler Classic Edge 560, WoodMaster– CleanFire 500 | Central Boiler Inc.- WoodMaster Inc. | Previously certified | 0.14 | 84% | 25,386–194,724 BTU/hr | 13.76 cu ft | Cord Wood |
| GARN WHS-1500H | DECTRA (GARN) | Previously certified | 0.14 | 65% | 177,000 BTU/hr maximum | Not listed | Cord Wood |
| GARN WHS-1500V | DECTRA (GARN) | Previously certified | 0.14 | 65% | 177,000 BTU/hr maximum | Not listed | Cord Wood |
| GX Series GX 10 | Hawken Energy | Previously certified | 0.14 | 64% | 144,870 BTU/hr maximum | Not listed | Cord Wood |
| EBW 200-170 | Econoburn Boilers | Previously certified | 0.16 | 60% | 171,638 BTU/hr maximum | Not listed | Cord Wood |
| GX Series GX30 | Hawken Energy | Previously certified | 0.17 | 67% | 242,090 BTU/hr maximum | Not listed | Cord Wood |
| Classic Edge 350 | Central Boiler Inc.- WoodMaster Inc. | Previously certified | 0.18 | 79% | 177,802 BTU/hr maximum | Not listed | Cord Wood |
| Classic Edge 750 | Central Boiler Inc.- WoodMaster Inc. | Previously certified | 0.18 | 72% | 240,362 BTU/hr maximum | Not listed | Cord Wood |
| E-Classic 1450 | Central Boiler Inc.- WoodMaster Inc. | Previously certified | 0.18 | 78% | 214,000 BTU/hr maximum | Not listed | Cord Wood |
| E-Classic 3250 IR | Central Boiler Inc.- WoodMaster Inc. | Previously certified | 0.18 | 69% | 245,000 BTU/hr maximum | Not listed | Cord Wood |
| FHG 20/30 | Fröling Heizkessel und Behälterbau Ges.m.b.H | Previously certified | 0.18 | 69% | 70,000 BTU/hr maximum | Not listed | Cord Wood |
| GX Series GX15 | Hawken Energy | Previously certified | 0.18 | 70% | 176,116 BTU/hr maximum | Not listed | Cord Wood |
| Mahoning Skye Series V | Mahoning Outdoor Furnace | Previously certified | 0.18 | 54% | 110,000 BTU/hr maximum | Not listed | Cord Wood |
| ENVIRO CHIP-500 | Piney Manufacturing | Previously certified | 0.19 | 73% | 280,000 BTU/hr maximum | Not listed | Cord Wood |
| G2-G2 | Polar Furnace Manufacturing Inc. | Previously certified | 0.19 | 67% | 200,000 BTU/hr maximum | Not listed | Cord Wood |
| Vedolux 30 | Varmebaronen AB | Previously certified | 0.19 | 62% | 109,529 BTU/hr maximum | Not listed | Cord Wood |
| GARN WHS-1000H and WHS1000V | DECTRA (GARN) | Previously certified | 0.2 | 77% | 160,000 BTU/hr maximum | Not listed | Cord Wood |
| GARN WHS-1000H, GARN WHS-1000V | DECTRA (GARN) | Previously certified | 0.2 | 77% | 24,000–160,000 BTU/hr | 8.83 cu ft | Cord Wood |
| USV 100GS | ESIM | Previously certified | 0.2 | 61% | 350,367 BTU/hr maximum | Not listed | Cord Wood |
| GT Series GT-6000 | Nature's Comfort LLC | Previously certified | 0.22 | 73% | 250,000 BTU/hr maximum | Not listed | Cord Wood |
| G Series G400G400s | Steel Tech, Inc. | Previously certified | 0.23 | 74% | 350,000 BTU/hr maximum | Not listed | Cord Wood |
| Crown Royal RS7400E | Greentech Manufacturing Inc. | Previously certified | 0.24 | 61% | 296,192 BTU/hr maximum | Not listed | Crib Wood |
| Phase 2-200 | Marway Welding | Previously certified | 0.26 | 39% | 139,576 BTU/hr maximum | Not listed | Cord Wood |
| 400-4S | Heatmor Manufacturing | Previously certified | 0.28 | 76% | 400,000 BTU/hr maximum | Not listed | Cord Wood |
| Crown Royal RS7300E | Greentech Manufacturing Inc. | Previously certified | 0.29 | 54% | 189,599 BTU/hr maximum | Not listed | Crib Wood |
| KB-125 | Hardy Manufacturing Co., Inc. | Previously certified | 0.3 | 61% | 119,457 BTU/hr maximum | Not listed | Cord Wood |
| Klear Sky 400 | Earth Manufacturing, LLC | Previously certified | 0.3 | 47% | 70,770 BTU/hr maximum | Not listed | Cord Wood |
| Optimizer 350 | Piney Manufacturing | Previously certified | 0.3 | 65% | 400,000 BTU/hr maximum | Not listed | Cord Wood |
| X Series 200X | Heatmor Manufacturing | Previously certified | 0.3 | 62% | 184,459 BTU/hr maximum | Not listed | Cord Wood |
| 350X | Heatmor Manufacturing | Previously certified | 0.31 | 58% | 255,582 BTU/hr maximum | Not listed | Cord Wood |
| Classic Edge 550 | Central Boiler Inc.- WoodMaster Inc. | Previously certified | 0.31 | 70% | 162,170 BTU/hr maximum | Not listed | Cord Wood |
| Empire Elite 200/XT200 | Profab Industries | Previously certified | 0.31 | 61% | 185,983 BTU/hr maximum | Not listed | Cord Wood |
| KB-165 | Hardy Manufacturing Co., Inc. | Previously certified | 0.31 | 57% | 150,000 BTU/hr maximum | Not listed | Cord Wood |
| 200 SSP | Heatmor Manufacturing | Previously certified | 0.32 | 69% | 180,000 BTU/hr maximum | Not listed | Cord Wood |
| Drummer-35 | Hydronic Specialty Supply, Inc. | Previously certified | 0.32 | 60% | 115,000 BTU/hr maximum | Not listed | Cord Wood |
| Wood Gun E155 | Alternate Heating Systems | Previously certified | 0.32 | 53% | 147,632 BTU/hr maximum | Not listed | Cord Wood |