By Colin Brougham

The following document details the conversion of 48-quart plastic picnic cooler into an all-grain mash tun, which will be capable of producing 5- to 10-gallon batches. This document is broken into three sections:
 
1)     construction of a CPVC manifold that lies beneath the grain bed
2)     construction of a CPVC sparge sprinkler that is attached to the cooler lid
3)     construction of a outlet valve and baffle assembly
 


The goal of this document is to show you how these parts can be constructed easily and inexpensively. Materials cost only $39. This conversion uses a cooler that has a pre-drilled drain hole, which forced me to be somewhat creative when it came to connecting the manifold with the valve assembly. So, while these instructions are specific to my situation, materials will differ only slightly based on whichever cooler you choose.

Manifold Construction
 

1. Cut five (5) lengths of 1/2” CPVC to fit the length of the cooler interior. Allow for an inch or so of clearance on both ends of the completed manifold, taking into account the added length of the fittings. Clean off burrs with a utility knife or sandpaper (do this for all cut pieces of CPVC—it will help prevent potential clogs or plastic in your beer).
   
   
   
2. Cut eight (8) 7/8” lengths of 1/2” CPVC.
   
   
3. Using four (4) of the shorter CPVC pieces, two (2) elbows, and three (3) tees, assemble one end of the manifold, with elbows on the ends and tees in the middle. Do the same for the other end of the manifold. (NOTE: It isn’t necessary to cement the CPVC pipe and fittings together. The pieces will hold together well enough on their own, and this also makes cleaning much easier. If you do decide permanently assemble anything, only cement the end of the manifold and use cement specifically for CPVC.)
   
   
   
   
4. Use the longer CPVC pieces to connect the two ends of the manifold. (NOTE: In the final section, I’ll describe how to connect this manifold to the outlet valve with a baffle. Since that step relies on the position of an existing drain hole, the connection position will vary.)
   
   
   
   
   
5. With a hacksaw or Dremel equipped with a thin cut-off disc (makes the process much faster), cut slits about every 1/2” along each of the longer CPVC lengths. No need to be scientific; just keep the slits as narrow as possible, and don’t cut more than halfway through the pipe. The CPVC will lose much of its rigidity, so be careful not to break the pipe. (NOTE: Instead of slits, you could drill holes in the manifold using a bit with a diameter of 3/32” or less. I opted for slits, as I think they’re less likely to get clogged with grain.)
   
   
   

 
Sparge Sprinkler Construction
 

1. The underside of the cooler lid will likely be beveled around the perimeter, leaving a flat region. Cut three (3) lengths of 1/2” CPVC to fit the length of the flat region. Once again, allow for added length of the fittings.
   
   
2. Cut four (4) lengths of 1/2” CPVC to fit the depth of the lid, again taking into account the added length of the fittings (in this case, you have two elbows and a tee).
   
   
3. Using two (2) of the shorter CPVC pieces, two (2) elbows, and one (1) tee, assemble one end of the sparge sprinkler, with elbows on the ends and the tee in the middle. Do the same for the other end of the sparge sprinkler.
   
   
4. Cut about 3/4” out of the center of one of the lengths cut in Step 1. Measure to the middle of the pipe, then subtract and add 3/8” from the center point. Cut this chunk out, and connect the remaining pieces with a tee.
   
   
5. Using the remaining longer pieces, and the assembly from Step 4, connect the ends of the sparge sprinkler.
   
   
   
6. Drill 3/32” or 1/8” holes in the pipe every 1/2” or so. Again, nothing scientific, though I did alternate angles on the center pipe, and angle the holes toward the middle on the outer pipes to better distribute sparge water.
   
   
7. Hold the sprinkler assembly up to the underside of the lid, and mark where the center tee touches the lid. Use a 3/4” spade bit to bore through the lid. (NOTE: You might want to transfer the measurement to the top of the lid and drill through that way. It’s easier to get the bit started on the flat surface of the top.)
   
   
   
8. Once again, hold the sprinkler assembly to the underside of the lid. Place two (2) of the CPVC hanger brackets on the center pipe, and mark position to pre-drill for the brackets. Drill the holes. Affix the sprinkler to the lid with the hanger brackets and some small screws.
   
   
   
9. GET CREATIVE. In my case, I use a small length of CPVC to connect the tee in the center of the sparge sprinkler to an elbow resting flush with the lid. This will be fitted with a quick disconnect of some sort to receive water from the hot liquor tank.
   
   

Next time we'll finish up our project by looking at the Outlet Valve and Baffle Construction... Click here to continue to Part 2...

• Called: Colin Brougham
  
• Lives: Cadillac, Michigan
  
• Works: Northern Michigan CBS affiliate, commercial/promo producer
  
• Brews: 6 months experience, partial-mash batches of every flavor of the rainbow; soon AG!
  
• Other: Kept on task by my wife, Rachel; when not brewing or building brewing gear or talking about brewing, I’m attempting alchemy with food, mishandling a camera, or assaulting a guitar