garn boilers
I have been looking into the Garn and several other gasification type boilers.
The companies that I have been looking into are: Garn-WHS, Greenwood - hydronic wood furnace, Seton, Alternating Heating Systems - Wood Gun and the New Horizon – EKO.
the Seton and Greenwood are identical boilers.
They are either down draft or refractory ceramic lined burners of various designs.
they all burn at very high temps, around 2,000 degrees, in a secondary chamber.
One of the problems is that they cost from 1-1/2 to 2 times that of a standard outdoor furnace.
Part of the added costs is that most are pressured boilers.
Some of the benefits of a pressurized system is they typically have a longer operating life span.
They use little or no chemicals.
They burn more efficiently - use about 1/3 to 1/2 less wood than a standard out door furnace.
They burn more completely - the secondary chamber burns the gasses and creosote, so there’s less smoke and less ash and have very low emissions.
They are physically smaller in size. The exception would be the Garn which stores energy in a water jacket that surrounds the boiler.
I think in the near future there will be an EPA maximum emission limit (.250 gm/1,000 btu) for out door boilers and furnaces and the only units that I know of that will be able to meet the standards will be the “gasification” type boilers.