Brewing with two or three vessels

The role of each vessel

• The hot liquor tank (HLT) heats the mash water, then the sparge water. A large pot or a water boiler with a tap is enough.
• The mash and lauter tun (MLT) keeps the mash at temperature for an hour, then lets the wort run off while holding back the grain. A 30 to 50 litre cooler with a false bottom, a braid or a slotted manifold and a tap is the most common homebrew version.
• The boil kettle receives the filtered wort and boils it with the hops, on a gas burner or with an element.

This separation allows batches of any size and any gravity, with no basket limit, and a careful sparge that gives good efficiency (75 to 85%). In return, the day is longer, there is more equipment to clean, and hot water has to be moved: a pump or vessels set at different heights saves carrying buckets.

Batch or fly sparge

• Batch sparge: you drain the mash tun, pour all the sparge water back in, stir, let it rest for 10 minutes and drain again. Simple and fast, it only needs a mash tun that is big enough.
• Fly sparge: the sparge water is poured gently over the grain at the same rate as the wort runs off, over 45 to 60 minutes. It needs a sparge arm and patience, and gains a few points of efficiency.

Stop sparging when the runnings drop to around 1.010 gravity: beyond that, you mostly extract tannins.

How much water for 20 litres

For 20 litres (5.3 US gal) in the fermenter, 5 kg of grain, a one-hour boil on gas (3.5 litres evaporated per hour) and 1 litre lost under the false bottom, the water volumes calculator gives:

Plan a boil kettle of at least 35 to 40 litres for 25 litres of wort: the kettle volume calculator gives the size for the volume and the margin you want. The mash tun must hold the water and the grain: about 18.4 litres of mash in this example (mash volume).

Brew day, step by step

Preheat the mash tun

A cold cooler absorbs a lot of heat. Pour a few litres of very hot water into it 10 minutes before mashing in, then empty it.

Heat the strike water

At 3 litres per kilo, the difference between the water and the mash is large: to hit 66 °C with 5 kg of grain at 20 °C in 15 litres, heat the water to 72.3 °C (see the strike water temperature), a little more if the tun has not been preheated.

Mash in

Pour in the water then the grain, or the grain then the water, stirring well. Measure the temperature in several places and correct it with a little hot or cold water (mash temperature correction). Close and leave for an hour. Meanwhile, heat the sparge water. The mashing guide details the possible steps in a cooler.

Recirculate (vorlauf)

Open the tap gently, collect the first cloudy litres in a jug and pour them back over the grain, until the wort runs clear. The grain bed then acts as the filter.

Lauter and sparge

Let the wort run into the boil kettle, then batch or fly sparge. Never let the grain run dry when fly sparging: the bed compacts and the wort stops flowing. Measure the gravity and the volume before the boil: the brewing efficiency calculator derives the efficiency of your setup from them.

Boil, chill, transfer

Bring to the boil, add the hops according to the recipe, cool with an immersion or plate chiller to 18-20 °C, then transfer to the fermenter, leaving the sediment behind. Measure the original gravity and pitch the yeast.

Powered variants

• RIMS: a pump circulates the wort through a regulated heating tube, which holds the temperature of the mash tun.
• HERMS: the wort circulates through a coil immersed in the hot liquor tank, which acts as a heat exchanger.

Both allow precise steps, like an all-in-one system, with the capacity of a separate setup.

Common three-vessel mistakes

• Forgetting to preheat the cooler: the mash loses 3 to 5 °C in the first minutes.
• A tap opened too wide at the start of the run-off: the grain bed compacts and gets stuck.
• Sparge water above 80 °C: tannins from the grain pass into the wort and give astringency.
• A gas burner used indoors in a closed room: carbon monoxide is dangerous. Brew outdoors or in a very well-ventilated space.