Sunday, 15 July 2012

Brewery Build #21: HERMS

After all the practice with pipe-bending and coil-design-practice, the actual HERMS unit was relatively simple, easy and cheap to build.  Four 1.2m lengths of 1/2 inch/12mm 0.9mm wall-thickness stainless pipe was bent into coils:
Two coils were bent in a clockwise direction and two in an anticlockwise direction, this way I was able to fit almost 5m of coil inside the $4 op-shop wine-cooler:
The hole-saw got some more use installing a 2200W 240V element from a $7 BigW kitchn-kettle in the base.  Interestingly buying, dissembling, only using the element and then discarding the kettle was a cheaper option than buying just the element from any source that I could find.  An old tube of silicon had hardened at the nozzle, so I had to cut it open to use it, so had an abundance of silicon to ensure it would not leak:
The inside-plastic-skin of the wine-cooler split a little while being filed back, however there was more than enough silicon to prevent that from being a problem:
Now-days it seems that the cheapest kitchen-kettles available for purchase are cordless ones, but luckily an IEC-type power plug:
.. plugs straight into the back of the 'cordless' part of the element socket:

I also removed the inside-thread from the top of the cooler so that the lid would snap-on rather than having to be screwed down:
Stupidly - after cutting, grinding, drilling and working with various power tools, stainless kegs and tubing - this was also when I hurt myself the most in the entire brewery build process.  Using an angle grinder to grind plastic is not a good idea since, unlike metal, the plastic tends to melt and burns like all fuck when you get it on your hands.

But the new HERMS-container passed both the boil-test:
... and the leak test:
Installed with fittings, it makes a clean and compact little unit (the PID probe slides into in the thermowell at the top of the t-piece):
 Inside is a double-helix/coil (which is why two coils were made clockwise and two anticlockwise):
With two elbows to secure the coil to the lid of the cooler:
For the moment - pending building a brew-stand - the HERMS enclosure sits ontop of the bottom of a 'modified' milk crate:

Complete and in use, it (according to the PID, since the dial-thermometer mounted on the kettle, and hence likely the actual mash temperature tends to lag a little) can raise the mash temperature by about 1 degree C per minute, which is what was aimed for:
The little brown pump has a flow rate of about 3L per min, which is likely a little slow to get a fast response from the grain-bed temperature, and since one of the little brown pumps has broken (after being used twice), it's likely that one of the first upgrades (yes ... talking about upgrades and not even finished building the system yet!) will be a new 'proper' home brew type pump.

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