A few years ago the EFM underfeed stoker was certified for burning pellets and the 520 was marketed as a multifuel boiler. I haven't seen any efficiency ratings but, as dc notes, the fuel/air feed rates are widely adjustable on those units so the efficiency with pellets shouldn't be too bad.dcrane wrote:Yes.. the main concern would be fire in the hopper if you use a coal stoker (like the LL) and put wood pellets into it. or the auto igniter in the Harman if you introduced rice coal into it, the draft would surly need to be adjusted differently for wood pellets vs. rice coal etc,etc... A wonderful dual fuel unit can be done and maybe is done already (maybe they cant advertise it as such).blrman07 wrote:Dcrane, I was trying to follow your posting but got confused. Maybe it's a terminology issue.
When you refer to "forced induction stokers" are you talking about stoves or furnaces that have a forced draft fan that supplies combustion air under the grate?
When you say that a stoker can be made to work equally well and as efficient as a wood pellet & rice coal burner I am not sure what your talking about because a very large percentage of stokers burn rice coal. I experimented with adding wood pellets to my stoker stove and was successful at a 30/70 ratio of wood pellets to rice coal utilizing a carpet feed system, not an up flow auger. 30% wood pellets to 70% rice coal worked. I didn't feel comfortable increase the ratio due to the flammability of the wood pellets in the hopper.
It was a nice experiment but that is all it was since where I am at wood pellets are over $200 a ton and rice coal is $170. If it flip flops in the future I know I can do the mix.
In terms of forcing a draft like that into large football field coal bed (that's what they do to melt iron, not heat a home)
So rest easy, all of you manly men laboring under the misimpression that you can't efficiently burn wood in your coal stoves. Cram in an EFM stoker, get a skirt, and you'll be all set!
Mike