Home > Brew gear, Tech geeks > Tun Tinkering

Tun Tinkering

For some time I’ve been putting off working on the mash tun return manifold, and I can’t exactly say why. This past week I finally lost patience with my own procrastination, dragged my son to Home Depot, and bought the materials required for a proof-of concept. I picked up a couple 2 foot lengths of PVC, some fittings, and headed back to the house. In hindsight I should probably have gotten CPVC so it could actually be used for brewing (PVC is only safe up to 140 deg F, whereas CPVC can basically deal with boiling temperatures), but oh well…

The concept was relatively simple:

  • A long standpipe that can be adjusted up and down to accommodate different grain bed heights
  • An elbow to kick the liquid out towards the middle of the mash tun
  • A tee to split the liquid into two parts (and reducing the velocity by half in the process)
  • Some 45 degree elbows to angle the flow upwards and away from the grain bed
  • A float switch to turn the pump on and off and maintain the proper liquid level

About two hours and several hose clamps later, I had a physical representation of the concept all built and functional, albeit very inelegant. I ran 3 or 4 gallons through the system to prove it worked effectively, and then headed over to check if the BrewzNET application was performing as expected and capturing the appropriate data.

The trendplot captures what happened nicely. The grant transfer pump kicked on pretty steadily and for a good number of seconds while the liquid transferred to the kettle. The transfer pump between the HLT and the mash tun kicked on much more frequently and for only 3-4 seconds – all it took to replace the small amount of liquid (1-1.5 qts?) that drained from the mash tun. For fun I put the transfer pump into “OVERRIDE: OFF” twice to allow the mash tun to drain a little extra beyond when the float switch would normally kick in, and then put it back in “Auto” mode. The transfer pump promptly powered on and topped up the tun again, although my BrewzNET application clearly did not register this happening. Something to debug there it appears.

I was pleased with the POC results and I am happy to know that things work (mostly) as planned, however it has left me with a number of questions and concerns.

  • How much heat am I going to lose with all that liquid sitting in the lines between the HLT and the Mash Tun? I have to minimize the length required to also minimize heat loss, I think.
  • Do I even want to use a single-level system given this concern around heat loss? Is it really such a big deal to use gravity to top up the tun? I need to do some soul searching here.
  • If I keep the mash tun manifold, do I rebuild it in CPVC or do I actually try to jump to all-stainless?
  • Dealing with so many hose barbs and hose clamps is a serious pain. Should I strongly consider polyethylene quick disconnects or maybe even tri-clamp fittings? I’ve got to do something different.

So as with most things related to my techno-brewing, I’m going to put these thoughts in the metaphorical carboy and see what ferments after a few weeks. There really is no rush to get them resolved since my gravity feed works fine, and I don’t need (or typically use) the grant setup for anything but 20 gallon batches. I should instead start looking at instrumenting mash tun and HLT temperatures, as well as some sort of gas solenoid valve for the HLT so it can automatically maintain temperature to a setpoint.

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Categories: Brew gear, Tech geeks
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