Franzinator Part III

As I pondered which of the myriad projects I would tackle last weekend, the fact that I could not, in good conscience, check off the Franzinator as complete, haunted me.  Sure, the weeds were getting out of hand and the trees needed mulching.  There are shutters and window planter boxes to build.  Yoda waits patiently in a corner (that is his specialty, though).  A half-built lamp ages gracelessly atop a pile of cherry wood that someday will take on a more intentional configuration, waiting for the moment that my eyes can no longer draw in enough ambient light to read the paper.  The grill needs new burners.  And the basement progress seems to be reversing as she gives up tools one by one back into the shop.

So, how then does the Franzinator rank immediate attention, especially since it was theoretically finished? 

Let me interject to give thanks that Saint Wife does not ask me these questions.  Humminahumminahummina....amen. 

Anyhow, the answer is simple:  every project needs air--painting the shutters and planter boxes, stain and seal the lamp, sandblast the grill (scrub? nonononono!), final lacquer coat on Yoda, nail gun for the basement.  And....I just don't like yard work.  Lame excuses?  Yes.  The reality is that I really am more interested in seeing the results of this project than the rest, and I am not satisfied that I am getting the best possible results.

Although the original Franzinator design had no inter-cooler at all, working purely from the flash cooling inside the vessel, I still believe that the inter-cooler is the coup des gras.  The method I employed to cool the vessel was to wrap it in copper tube with chilled water circulating through the tubing with lots of insulation around the whole shebang.  Logical, no?  But, as I mentioned in the earlier post, the copper tubing is not conducting because it is not attached to the steel tube vessel.  It is not possible to wrap the tubing tightly enough to ensure conduction, so I was only getting convection, which was meager at best.  So I reasoned that the inter-cooler was probably not contributing much to the equation, and set about rectifying the situation.  (Note:  rectifying does not mean sitting on your ass doing nothing, even though it seems like it should.)

First step, remove insulation and copper tubing, grind the steel pipe to get a good bond able surface.  Intent was to re-wrap the copper tubing and braze it to the pipe to get actual conduction.

 

I dry-fit the assembly back in place and welded the brackets so that they would be in the proper position after I brazed the tubing to the steel pipe.  As I welded, I was not unaware that this permanence surely preceded folly.  Later I would have to grind them off.

That Saturday went down as a lesson in metallurgy.  Using a mini oxy-acetylene torch and various blends of solder and brazing rods, I was unable to get a bond to the steel pipe.  I had learned that flux was not necessary when brazing, but tried anyway after hours of failing without it.  Didn't work.  In a moment of desperation and frustration, I even tried to MIG weld it.  Of course, we all know academically that was a stupid idea.  But sometimes empirical success comes to those willing to ignore logic. Not this time.  What it did do was melt the tubing instantly.  Duh.  So with a new problem, I tried to repair the tubing, which I have done before with ease.  Not today.  I tried to swedge and solder.  Nope.  I tried to sleeve with a larger ID tube.  Nuhuhh.  Simply put, Saturday was not to be Solderday.  Sometimes it goes like that.  It was dinner time.  I turned off the lights and went in for family time.

Sunday started with a hint of promise as Saint Wife decreed that we would not be attending church that day.  I did not need to know why--a gift horse has good teeth.  This gave me a huge head start on Plan B.  The seeds of Plan B were sown by my good friend who is much smarter than I--a real Mr. Ego-crusher.  I initially rejected his idea because I was certain that my coil idea was more practical (and determined to prove that it would work, dammit).  His suggestion was to use a water jacket instead of a coil.  The problem, I reasoned, was that there wasn't a good way to deal with the air line in, the air line out, the bleed valve, and the water lines in and out.  I had been trying to envision a solution to this concept even as I was building my version with the coil.  But with failure on my heels, a gin-lubed thinker, and an hour and a half of watching a Disney movie with the kids, inescapable except into my imagination, I formulated the latest version.

4" PVC sanitary pipe.  Unfortunately, not garden-variety.  Apparently, the value-gods have decreed that foam-core PVC pipe is okydoky for sewer pipe, so that is all that is stocked at the home center.

I needed to tap NPT threads for PVC bushings for the water lines and was concerned about this foam core non-sense.  So as a precaution, I glued a reinforcing patch, then tapped through both.  I did not have the exact drill bit required, so I went 1/64 smaller and it still tapped easily, which was a little troubling.  Since I had insufficient faith that only threading the two PVC parts together would be water tight, I also glued them.  Another harbinger of doom.

Here is how it all goes together.  I solved the air in problem by bypassing it.  It turned out that a standard 4x3 reducing NIBCO fit the OD of the steel fitting flange and the ID of the PVC perfectly.  Go figure.  I connected the water to both ends of the vessel with a piece of the tubing of which I now had a huge surplus.  Of course, one of the bushings leaks, probably because I glued it, so I will have to drill it out and re-do it, but it will be easy since the whole thing comes apart with minimal effort.  Foam core PVC is to blame, in my opinion.  I will re-do with proper pipe.  I am also dissatisfied with the strap I used to hold the whole thing to the bracket.  I couldn't find a 4" pipe collar, so I used strapping that I recall buying to hold some pipe in my first house remodel circa 1991.

And here is the final assembly.  Other than the small bushing leak, it holds water and seems to work well. When I first filled it up, the NIBCO fittings bulged a bit, giving me pause, but they held.  I barely got it all together Sunday, so I haven't taken any temperature readings yet, but I am confident that this will be very effective.  You can see in the picture how I fill the unit with water--simple hose connection to a needle valve on the water cooler reserve tank drain line.