After I recalled that I have over a dozen of Blissfield condenser coils (about 8x10 inches, very nice easily mountable coils, which I plan on selling for $10 each), I added one to my TIG water cooler. I suspect that it will be there mostly for looks, and not needed to cool the coolant, but perhaps one day it would actually be helpful.
Many new pictures are here
I am glad that I was able to detect this dangerous overpressure.
Doubtless, I need to buy and install a pressure relief valve ASAP.
Any suggestions for a suitable relief valve? There are various kinds over there and I am lost. I would prefer something with 3/8" NPT male connections.