A Hot Box 140
The big Keene 151 drywasher, very popular because of its large size and its hot air system.
The motor blower sucks air down around the hot engine and through the blower and out.
They claim preheated air up to 50 degrees above ambient temp.
This is their Honda version, they now use a Briggs and Stratton engine. Hot air is good
when working with damp dirt, it tends to dry it out and that helps get the gold out.
You may still have to run the dirt a couple times to completely dry it.
The Keene 140 is the smaller light weight version of the 151. It also uses a forced air method
to move the dirt down the riffle tray.
Most prospectors use a leaf blower of some sort to get the air to run it and it may also
double as a vac pac for cleaning bedrock. The dilemma has always been this is not a
hot air system like the 151, it just pushes out ambient temp plus a little maybe 10 deg.
On a hot August day you get a normal temp of 84 deg F.
I set my blower in a Lowes heavy duty 12x12x16 box cut holes for engine intake, engine
exhaust, and blower output. I fired it up and got the following results for temp.
You got to pipe that engine exhaust out of the box or it will send oil up to the
riffle tray and we don't want that.
Now I'm not saying you should run a blower in a box in August at 144.7 deg F and expect
it to last very long. It does show you can heat up your air if you put it in a box though.
If you run the engine in the box with it open it still will heat up the output.
Here we still get a 30 deg increase in temp with a open box and it isn't as hard on the motor.
Also note that the loading at the drywasher (the dirt coming down the riffle tray) will cause a
increase in output temp of the motor above that running an open riffle tray. When looking at
blowers be aware that the low noise versions (most around and under a $100.00) may have
their exhaust piped into the blower pipe. That isn't good for our riffle tray cloth and gold
catching static charges that will not be generated now, an oily mess will be building.
If you run a hot box 140 let me know how it works for you.
Good luck Prospecting!