Stokermatic Superheater Manual & over-fire air jet

I do not have a stokermatic stove, but have seen a few in Wyoming. I own a Prill underfeed stoker. One difference between these stoves (among many) is that some models of the Stokermatic have an "Over-fire" air jet. At the end of the stokermatic manual (attached) it shows the overfire air jet and describes it as "greatly increasing the burning efficiency". From what I've read, it increases turbulence and mixing.

Anyone have any experience with how these work? Does the jet live up to Stokermatic's claims? I was pondering adding one to my Prill, but wanted your thoughts. Is the air preheated at all? What percentage of air is under vs. over? Do they use a separate blower, or is it just ported off of the same blower as underfire air?

Your thoughts appreciated.

Thanks,

Steinke

BTW - the pages seem out of order in the manual, but if you print it doublesided, you can staple it together like a little booket, and the pages are in the correct order.

Concerning your question about the overfire tube.
The overfire tube comes from the airbox, the air comes from the combustion fan that blows air through airbox and then through the tuyeres. What percentage of air comes through the overfire tube would have several factors. How clean is your airbox (is it full of ash and rocks). Also the air holes in your tuyeres, have you cleaned them to get the small rocks out of the holes. Sometimes they can get so full of small rocks hardly any air can get through. If everything is clean you would about 10% of the combustion air coming through the overfire tube. It blows air down on the fire and spreads out the flames so that it heats the outsides of the firebox better thereby making the stoker use the heat from your fire more effentiently.

You could add an overfire tube to a combustionaire or stokermatic but you would need to break out the refactory cement in the bottom of your firebox, then drill a hole (the hole goes against the leftside near the back) for the tube in fit down into the airbox and secure it so it doesn't fall to the bottom of the airbox. Then put new refactory cement on the bottom of the firebox.
Hope this is helpful.
Annette
http://www.stokerworx.com