Woodstock Keystone 204 wood stove

Woodstock Soapstone rates the Keystone 204 for 800–1,300 sq ft with an output of 46,437 BTU/h (top of the EPA cordwood test range). The firebox holds 1.4 cubic feet, #19 by size of the 20 stoves listed here, and particulate emissions are 0.85 g/h, 43% of the EPA's 2 g/h limit.

1Heating area 800–1,300 sq ft
2Output 46,437 BTU/h
3Firebox 1.4 cu ft
4Particulate 0.85 g/h

Specification	Woodstock Keystone 204
Heating area	800–1,300 sq ft
Output	46,437 BTU/h (top of the EPA cordwood test range); low 9,989 BTU/h
Efficiency	80% (EPA 2020 efficiency; the page does not say HHV or LHV)
Particulate emissions	0.85 g/h
Firebox	1.4 cu ft
Log length	up to 16 in
Flue	7 in
Weight	440 lb (stove weight)
Burn time	8 to 10 hours
Same published ratings	Woodstock Palladian 202

Published output of the Woodstock Keystone 204 and the four listed stoves closest to it. Makers define the figure differently (maximum, top of the EPA test range, or constant output on High); each stove's page says which. Bars to scale from zero.

What the Keystone 204 heats

On this site's floor-area pages the Keystone 204 appears for the up to 1,200 sq ft and 1,200 to 2,000 sq ft bands. At its top rating of 1,300 sq ft, a 1970s house in Oregon needs about 19,532 BTU/h on a 0°F night, below the stove's 46,437 BTU/h. The same floor area built before 1950 in North Dakota needs about 24,991 BTU/h, which the published output still covers.

Floor area	1970s house, Oregon	Pre-1950, North Dakota	Within 46,437 BTU/h?
1,000 sq ft	15,024	19,224	Both
1,500 sq ft	22,537	28,836	Both
2,000 sq ft	30,049	38,448	Both
2,500 sq ft	37,561	48,061	Median state only

These are estimates from average use, not a heat-loss calculation of a real house, and a stove heats the room it stands in first. The Keystone 204 runs from 9,989 to 46,437 BTU/h, a 4.6-to-1 range, which helps in mild weather when a big stove would otherwise be turned down and smoulder.

Wood it burns in a winter

With its published 80% efficiency, heating 1,300 sq ft (built in the 1970s) on generic 20 million Btu cords takes about 2.4 cords in Oregon and 4.1 cords in North Dakota. It takes logs up to 16 in, so standard 16-inch face-cord wood fits; University of Maryland Extension suggests cutting wood about 3 inches shorter than the firebox. The maker quotes 8 to 10 hours per load.

The species that burn best in any stove are the dense hardwoods Utah State rates excellent overall: osage-orange (30.5), black locust (28.3), white oak (27.9), apple (27), bur oak (26.3) million Btu per cord. Burn them dry; see how to season firewood.

Emissions and EPA rules

At 0.85 g/h the Keystone 204 is 43% of the EPA's May 15, 2020 limit of 2 g/h and 34% of the 2.5 g/h limit for stoves certified on cord wood. It is a catalytic design. The EPA rules guide explains the limits.

Similar stoves

Woodstock Fireview 205: 46,460 BTU/h, 900–1,600 sq ft
Woodstock Progress Hybrid 209: 47,220 BTU/h, Up to 2,200 sq ft
Drolet Fox: 45,000 BTU/h, 250–1,200 sq ft
Woodstock Absolute Steel Hybrid 211: 48,000 BTU/h, Up to 1,800 sq ft

Source: Woodstock Soapstone Co., Keystone soapstone wood stove page, checked 2026-10-20. Ratings are the maker's own; installation clearances and permits follow the installation manual and local code. See the methodology.