Will a Thien separator work for me?

[socloseyetsofa]

I'm considering building a vacuum system to remove the ashes from my wood/coal boiler.  The full ash pans are very heavy and shoveling them out takes a while and makes a heck of a mess, no matter how careful I am.  No to mention a lot tends to miss the pan.  I've done a fair bit of reading on here and there doesn't seem to be a consensus whether or not these things work well with very fine dust.  People say no but then I see people claiming 95%+ capture sanding MDF, even a couple were diamond grinding concrete with good capture. 

My thoughts are to return the exhaust back to the boiler opposite the intake (maybe multiple points) to push the ashes to the intake.  This would eliminate the the need for filters as well as fears of pulling toxic gases from the boiler (not that I plan to use this while the fire is lit).  However without filtering any bypass would need to be picked up of subsequent passes, it does no good to be blowing 10 lbs of fly ash in a circle. 

I have a 1hp 4 inch Cincinnati blower kicking around and would like to use a 55 gallon drum as the bin, but nothing is set in stone.  Obviously it would have to be built from all metal for fire safety, I am a fabricator by trade so that is no issue. 

Thoughts/comments?  Am I even more out of my mind than usual?

[Schreck]

That's a bigger bin and a smaller blower than we normally see.  You may want to build a quick trash can lid type of build (not a top hat) and run the exhaust outside.  If the separation is good enough, you can then address the filtration v. return air issue.  Returning air to the boiler could make a mess if it disturbs the remaining ash.