Gaggia Preheater Construction Rev 2

There were a few things I did not like about my first preheater, so I decided to give it another try.
You can read about Rev 1 here
Revision 1 preheater construction

I hoped to reduce the recovery time, and also hoped to lower the temperature drop in the output of the preheater during the shot.

I picked a different box for the preheater, this one is thinner then the one used in Rev 1.
This is the box I used for Rev 2
Hammond 1590WG

Drawing of the box
1590G pdf drawing
This box is thinner then the first one, 0.8 versus 1.2, so it is 50% thinner, which should help the recovery time.
This box is longer then the first one.  I found a heatsink from All Electronics that happened to fit almost perfectly, when cut in half.  Just took a little filing to get them to fit right.
Heatsink
I added 7 of these inside my box, pretty much filled it up.  I measured the volume with and without the heatsinks, and surprisingly the heatsinks did not effect the volume very much, maybe a 1/4 oz at most.
I glued the heatsinks in place with food safe epoxy from Mcmaster, then used RTV to seal around the heatsinks.

For the fittings in the preheater, I decided 90 degree elbow fittings would work better then straight ones
1/8 BSPT x 6mm elbow

I also decided to use a better 6mm coupling, one that handles a higher pressure
6mm coupling
Even though the first one didn't leak, this one is better.

Few more pics.

I put a bead of RTV around the top, then put the top on, and installed it back in my Classic.

Turned the Classic on, and it looked OK at first, then I noticed water around my Classic.  After a little investigation, I found the source of the water, it was coming out of the thermocouple.  The thermocouple wirre is double insulated, so I think it was leaking out between the layers of insulation.  :(

I took the preheater apart, and stripped back the thermocouple so there was only one layer of insulation for the wire inside the preheater.