So after quite a few calls and some research; The only way to get a replacement top portion to the heat exchanger was to purchase an entire new exchanger. This would run $1400 to $1800 for the part alone, which is WAY to expensive IMHO and out of the question. Honestly, at that price I'd rather get an completely new unit. I decided to attempt a repair since I have nothing to loose with this unit.
After disconnecting the fan and control panel wires I removed the entire outer lid of the aquacal. This was to gain better access to the heat exchanger. Once inside, I confirmed the heat exchanger upper, lower and outer portions are completely plastic. I'm betting the only place titanium is actually used is where the coils inside meet the water to heat/cool. I used a dremmel with wire brush attachment at first but then switch to rough sandpaper to roughen up the plastic surface. I also used a blade to score the outer areas in a crosshatch pattern to give the surface some additional cling. I worked around the entire area in question and moved further out for good measure. Once fully scored, I used rubbing alcohol and a clean rag to remove all surface residue and dirt. After drying, I mixed an entire 2oz set of JB WELD marine grade epoxy. This is the slower curing (24 hour version) and is supposedly better suited to wet/marine conditions. I applied it to the entire surface (like icing a cake) and let it set for 24 hours. The next day I reconnected everything and tested it out!
So far... so good. No leaks! The true test will be the longevity of this patch. I've had mixed results with JB WELD in the past. It either works and last forever or fails in a short amount of time. I feel mostly it has to do with the surface area prep. I'm hoping that since this part has no friction, no real heat, minor vibration and only a minor amount of water pressure to contend with, it lasts. At a cost of $6, I'd rather take this chance than just take the Aquacal to the scrapyard.
I'll post an update if it fails OR if it lasts. If it works, hopefully others in the same boat as me will have luck with JB WELD.
