Mash Tun Upgrades

Following up on my last post, I decided to pull the trigger on the Bargain Fittings cooler kit. I ended up going with the standard 2-piece valve instead of the 3-piece, and a ³⁄₈” hose barb. I also picked up two of the new ¹⁄₂” clear silicone gaskets, which I knew I’d need to work around a flaw in my mash tun (more on this later).

The parts arrived a few days later via USPS, and they look awesome compared to the dingy brass fittings they’re replacing.

The recessed lock nut itself is a beautiful piece of hardware. Had I known how nicely these parts work together, I might have spent the extra cash from the beginning and saved myself a lot of time and hassle, but it seemed like something I could approximate with fittings from the orange box store. How wrong I was.

I spent an inordinate amount of time when I first built my mash tun trying to get a good seal. After much cursing, I finally succeeded, but not before I accidentally dished the inside of the cooler wall. I must have overtightened the fittings at some point and ended up crushing some of the insulation, so the cooler lining around the drain hole looks like a very shallow funnel, which resulted in too steep of an angle for the silicone o-ring and lock nut to seal on alone. This is where the flat silicone gasket comes in.

It just so happens that if you take a ¹⁄₂” CPVC butt splice, file out the ring inside so it’s flat, and split it with a Dremel or a hacksaw, that it will fit around the 2″ NPT nipple. So, on the outside of the cooler, the washers push on the CPVC splice as the whole assembly is tightened, the splice, in turn, pushes the silicone gasket against the outside face of the inner cooler wall, and acts to straighten out the distortion.

Looking at the above image, the left hand side up to and including the gasket will be pressed against the outside of the inner cooler wall. I had to carve out a bit of insulation to make this all work, and it takes some trial and error to get the width of the CPVC splice right, but it should take no more than half a pint of beer to get everything dry-fit so you can move on to actually installing the fittings.

You can see here how the stainless washers put pressure on the modified splice and gasket, helping to form a seal from both sides without allowing wort to escape and be trapped in the cooler insulation.

That’s it! After tightening up the ball valve just enough so the assembly doesn’t freely spin, I did a quick leak test with a gallon of water, and found none after an hour. I’ll most likely do another test with several gallons of hot water, because I’ve found the extra hydrostatic pressure combined with hot water tends to find it’s way through smaller cracks, or create enough expansion in parts to cause new leaks to appear.

Next up, I need to figure out how to modify my copper manifold to attach to the new coupling without creating more dead space.