Outdoor EPA Boiler Information

Understanding EPA Phase I - Hydronic Boilers - PDF (69 kb)
The Phase 1 orange tag means the model pollutes about 70% less than unqualified models.

Understanding EPA Phase II - Hydronic Boilers - PDF (67 kb)
The Phase II white tag means the model pollutes about 90% less than unqualified models

Polar EPA Phase 2 Boilers
Polar G2 - EPA Phase II
Polar G3 - EPA Phase II

Wood pellet boilers are also listed in the same EPA Phase II Category

Understanding how the tests get performed.
EPA Hydronic Boiler Tests are designed to test the emissions of the heating appliance, the
EPA Btu listed ratings are generated from results of the controlled EPA emissions test and
may not represent the actual Btu output of the appliance.

The EPA Wood Hydronic Boiler Emission Tests are performed with fire wood of a specific type,
density, moisture content and specific amount of firewood (we currently have not been provided
the type of firewood used) for a defined eight hour period of time. This is to set a standard to
ensure that all wood fired hydronic boilers are tested the same, with consistent, comparable
and controllable results in regards to emissions.

The EPA test Btu rating does not represent the potential Btu output of the appliance, as this
is not using cordwood or testing the hydronic boiler or heating appliance to its fullest capacity.

Wood stoves typically have two Btu output ratings. EPA test Btu and Cord wood Btu.
See the specifications of the Osburn 2400 Wood Stove as an example.
The EPA test 40,900 Btu and cordwood Btu 100,000 rating on this stove.
The smaller the firebox the tighter the Btu between the EPA test and cord wood rating.
See the specifications of the Osburn 1100 Wood Stove as an example.
The EPA test 35,000 Btu rating and cordwood Btu 45,000 rating on this stove.

The amount of wood used for the test on the Wood Doctor HE8000 was 130 pounds of firewood.
The hydronic boiler was tested over an eight hour period. The test information received did not
indicate whether the boiler burned all the firewood in the eight hour period.

The test burn of 130 lbs of EPA test firewood created 896,000 Btu of useable heat between
160 and 180 degrees Fahrenheit. So 896,000 Btu divided by 8 hours = 112,000 Btu / hour.

In a controlled laboratory burn, it is possible to get 8660 Btu/lb of wood fuel, no more!

Again what kind of wood was used by EPA for the test?
As in order to get the EPA 76% rating of this appliance the results indicate the input Btu
of the wood used would have to have been 1,178,947 Btu/130lbs or 9068 Btu/lb of wood.

The EPA emissions test only filled the firebox of the Wood Doctor HE8000 to less then half
ofits capacity based on its 13.3 cu.ft. of firebox. As even using white poplar with a weight of
2370 pounds per 128 cu.ft. of "stacked" cord of wood, is 18.5 pounds per cubic foot would
increase the wood capacity of the firebox to 240.5 pounds of firewood and if you optimally
stacked the wood in the fire box and managed to increase the density of firewood to 100 cu.ft.
of solid firewood per cord (optimum being 80 cu.ft. of solid wood) you could possible increase
the capacity to 23.7 pounds per cu.ft.. So 23.7 pounds per cubic foot times the 13.3 cu.ft.
of firebox = 315 pounds of firewood compared to the EPA test wood weight of 130 pounds.
This is a potential 240% difference in firebox capacity.

Ultimately we need more detailed information on the firewood used and tests actual procedure.

Previous tests in the Wood Doctor yard of the HE8000 with a starting temperature of
180 degree Fahrenheit produced a draw of 300,000 Btu for the first hour (this is because
50,000 + Btu can be stored in the water jacket of 150 gallons between the drop
in temperature from 180F and 160F)and the 248,000 Btu / hour thereafter.

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Last modified: 04/18/15