Monday, 10 March 2008

Big Brew Day Using The Pebble Bed Mash Tun

Brew-buddy Dan and I had been speaking for a while about using a large plastic storage box as a mash-tun. He has long used a smaller one in his own brewery when he feels too energetic to Brew In A Bag. Sometime around the end of last year, I found some deliciously cheap 135litre storers in the local supermarket and bought one. Our Big Brewery was now a design in progress.

Time passed. A poster to (known as pumpy) wondered aloud if gravel might work as a drainage medium in a tun or kettle. Nobody knew, so I decided to incorporate it into our mash-tun design. In a parallel effort, I was dreaming up a way to over-complicate my Pilot Plant Kettle, which involved (among other things) a hose-braid hop-stoppa. A couple of metres of Brewers Favourite Swiss Voile, a compression-fit ball valve and I'm in business.

We needed a brewery to incorporate this into, so I summoned a small group of crack brewers and their equipment.

On the basis that we were brewing a Big Beer, Michael furnished the recipe for a Wee Heavy:

% Amount Name Origin Potential EBC
78.3 38.00 kg. Pale/Lager malt Australia 1.037 4
8.2 4.00 kg. Munich - JWM Light Munich Australia 1.038 15
7.2 3.50 kg. Crystal 25 - JWM Light Crysta Australia 1.034 50
2.4 1.18 kg. Crystal 135L - JWM Dark Crys Australia 1.033 275
2.4 1.18 kg. Roasted Barley - JWM Australia 1.029 1350
1.3 0.65 kg. Wheat Malt - JWM Australia 1.039 4

Amount Name Form Alpha IBU Boil Time
115.00 g. Pride of Ringwood Pellet 9.80 28.9 First WH
40.00 g. Goldings - E.K. Whole 4.75 1.5 20 min.

We were hoping to achieve 105 litres of 1.092 wort.

Everyone brought loads of kit, which we assembled thusly.

60litre and 75litre kettles on the first floor balcony acting as electric Hot Liquor Tanks:

From Big Brew Day

The Pebble Bed Mash Tun (in this photo being given a final rinse before the Swiss Voile liner is installed:

From Big Brew Day

And with the liner in place:

From Big Brew Day

Mashing In nearly 49kg grain took some time:

From Big Brew Day

It really did take some time:

From Big Brew Day

But we got there eventually and after an action-packed ninety minutes or so we considered the mash complete and set up the receiving grant, pump and links to both kettles. This proved to be a lot easier to use than anyone expected.

Mid Set-Up:

From Big Brew Day

In Use:

From Big Brew Day

We kind of fly-batch sparged and ended up with about 150litres in the kettles, which mysteriously boiled over.

From Big Brew Day

From Big Brew Day

We boiled for 90 minutes and found something else to do in the interim...

In spite of the compleat lack of science applied on the day, we ended up with five cubes of wort at a bit over our target gravity - so we did pretty well.

Dan brought along a bottle of beer to enjoy towards the end of the exercise and if ours comes close, I'll be a happy man.

There are a couple of improvements I would make next time. I would treat the plastic storer as a liner and build something structural out of timber to put it in and avoid the distortion. Although we pre-heated the pebbles before mashing in, I would add more heat to the tun to make hitting our mash temp easier. I would put temperature controllers on the Hot Liquor Tanks to make that more interesting.

In all, the system worked very well. The sweet liquor came out of the tun beautifully clear, so the combo of Pebbles, Swiss Voile and Hose Braid Hop Stoppa worked as well as you could expect. The Receiving Grant and Wort Pump were fabulous. It was just one of those days where the planning seemed to pay off.

Of course, it was the brewers that really made it work.