Tag Archives: cooler

The Cooler Mash Tun Project

Before I get started, I must proclaim that I attempted to copy a blueprint that I found on the Home Brew Talk Wiki page.  While I attempted to perfectly imitate the end result, material availability forced me to veer off a little bit.


After researching different cooler mash tuns, I decided to go with the 10 gallon Home Depot cooler with the stainless steel braid filter.  My original goal was to find a 48 quart or bigger ice chest and use a copper manifold for the inside.  The bigger coolers proved to be very difficult to acquire; after checking Craigslist, Wal-Mart, K-Mart, boater retailers, Home Depot, Lowes, and grocery stores, I gave up and went for the path of least resistance.  Once I decided the type of cooler, I juggled whether I was going to use a copper manifold or stainless steel braid filter.  Research showed that everyone likes both of them and brewers usually stick to what they have until they decide to substantially upgrade their system.  I opted for the least expensive route.


The above mentioned Wiki article prepared me with a shopping list to take with me to Home Depot.  The list is as follows:

  • Rubbermaid 10 gallon round beverage cooler
  • all stainless steel ¼” hose clamps x 2
  • brass square head plug (Watts A-737)
  • ½” x 12” (or larger) braided stainless steel supply hose
  • 3/8” female barb adapter (Watts A-298)
  • 5/8” stainless steel fender washer (Note:You can convert a 1/2″ SS fender wash by widening the hole to 5/8″ if you cannot find one. Most hardware stores do NOT carry 5/8″ ID fender washers.)
  • 3/8” MIP x 1-1/2” brass nipple (Watts A-786)
  • seal from plastic spigot of cooler
  • Teflon tape
  • 5/8” Inner Diameter O-ring (preferably heat resistant, if you can find one)
  • 3 x 5/8” fender washers (newer coolers seem to be thin around the spigot and may need 5 or 6 instead of 3) <–More than 3 are needed
  • 3/8” threaded ball valve
  • 3/8” male barb adapter (Watts A-294)


I was able to acquire everything except the 3/8” threaded ball valve.  Rather than upgrading everything to 1/2” and risking the pieces not fitting, I simply bought a 1/2″ to 3/8” reducer and a 1/2” threaded ball valve (more on that later). I also added a stainless steel lock washer, because I did not achieve the required thickness with the above materials.

1/2" ball valve


 Using the Wiki directions, I began the construction of my very first mash tun.  Along the way, a couple of head-scratchers were lined up to impede my progress.  The first of which was the aforementioned elusive 3/8″ ball valve.  After checking three Home Depots and a Lowe’s, I decided to buy the 1/2″ ball valve and convert the 3/8″ brass nipple to 1/2″ with a coupling (Watts A-177).  With the 1/2″ ball valve, I had to get the 1/2″ male barb adapter and not the 3/8”, as prescribed.  The other issue that popped up was that the length of the brass nipple was much longer than the width of the cooler, near the spigot.  After coming up short with six washers, I used a thick 5/8″ lock washer and 4 regular washers to achieve success.  The lock washer was placed on the bulkhead side of the cooler, between the coupling and the washer that butts up to the O-ring. 

Watts A-177 coupling


The inside portion of the mash tun went without a flaw.  The only modification that I made to the original plan was that I stacked up three stainless steel washers between the barb and the cooler in order to take up extra space.  In our next brewing session, I will give this bad boy a whirl.  Stay tuned.


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