Whirlpool and Lauter Design: What Changes in the Cup
Two hot-side steps decide how clean the wort is when it reaches fermentation, and both are design questions rather than brewing technique. Lautering separates sweet wort from spent grain; the whirlpool gathers hop debris, protein and trub into a cone so clear wort can be drawn off the side. The Brewhouse vessel sets published by HGMC run from two to five vessels with steam, direct fire or electric heating, and the internal details are what a buyer should be comparing.
Key takeaways
- Published fabrication is TIG 100% full welding with polishing to 0.4 microns or better, which is about surfaces that clean rather than looks.
- Piping is designed to avoid wort aeration, so the clarity won at the whirlpool is not lost on the way to the fermenter.
- Jackets on both body and cone plus separately calculated cover headspace are published tank details that hold a boil and a whirlpool steady.
- Materials are stainless steel 304 and 316 with 3 mm and 2 mm plate, and the food-grade SUS304 material is published as certified by SGS.
Lautering decides the shape of the brew day
Lautering is a filtration job: the grain bed itself is the filter, and the way wort is drawn through it sets both clarity and extract yield. A vessel designed for it has the right false bottom, the right draw-off geometry and enough surface area that the bed does not compact under its own weight. Where lautering shares a vessel with mashing, the brewer waits for the bed to settle and run-off is slower, which is why the published configurations separate the steps as vessel count rises. Two, three, four and five-vessel sets are published, and each extra vessel buys sequencing: the next step can start while the previous one finishes, so a brew day costs less time rather than less attention.
Whirlpool: separation, not decoration
Whirlpooling is a settling problem solved by geometry. After the boil, wort is pumped into a tangential flow so it rotates slowly, letting dense particles migrate to the centre and form a cone of trub. The clear wort is then drawn from the side, away from the cone. Design variables — vessel diameter, the depth of the wort, the entry angle and the draw-off height — decide how sharp that separation is. Get it right and the fermenter receives wort with very little coarse material in it; get it wrong and the same wort carries proteins and hop fragments that later show up as haze, harsh bitterness and extra tank losses. The rest is the part buyers can verify: 100% full TIG welded joints and a polish to 0.4 microns leave fewer places for residue to sit, and piping arranged to avoid aeration protects the wort on its way out.
Design details worth asking about in writing
Published specifications make the comparison concrete, and they are worth putting on the same page as the price. Control level also matters on the hot side: a PID display panel, a PLC semi-automatic touch screen, or a fully automatic PLC with curve indication and production-record printing. The last option matters most for a brewery that wants to prove a batch was brewed the same way as the one before it, because the record is produced by the system rather than written up afterwards.
| Design detail | Published specification | Effect in the tank |
|---|---|---|
| Welding | TIG 100% full welding joints | Fewer crevices, so cleaning reaches the joint as easily as the plate. |
| Surface polish | Accuracy 0.4 microns or better | A smoother surface sheds protein and hop residue between brews. |
| Piping layout | Designed to avoid wort aeration | Less oxygen pickup between kettle and fermenter, so flavour holds. |
| Jackets | Specially designed jackets on body and cone | Even heat transfer during the boil and a controlled fall in temperature after it. |
| Headspace | Cover headspace volume calculated separately | Room for foam and for a full rotating whirlpool without loss over the rim. |
Decoction or infusion changes the vessel set
The published design allows either decoction or infusion brewing, and that choice reaches back into the hot side. Infusion mashing holds the whole grist at stepped temperatures in one vessel, so it asks for even heating and reliable control. Decoction pulls a portion of the mash out, boils it and returns it, so it asks for an extra vessel or a pump circuit, plus the heat capacity to boil a third of the mash while the rest rests. Neither method is wrong; they simply size the plant differently. Tell the design team which one you brew before drawings are fixed, because the answer changes the vessel count, the pipework and the heating load, and those are expensive to change after fabrication.
Worked example: what a point of trub costs over a year
The figures are ours and the assumptions are stated. Take a 2,000 litre batch, which is 2,000 / 117 = about 17.1 barrels. Assume kettle trub and hop debris amount to 3% of the batch, that is 2,000 x 0.03 = 60 litres, and that a well-designed whirlpool leaves 40 litres of that behind in the vessel while 20 litres still carries to the fermenter. If a redesigned draw-off reduces carry-over from 1% to 0.5% of the batch, that is 20 litres down to 10 litres, so 10 litres more beer per brew. At 200 brews a year, 10 x 200 = 2,000 litres, which is about 17 barrels of beer recovered a year. Note what the calculation does and does not say: it assumes the lost volume is otherwise unsaleable, and it ignores any change in fermentation behaviour. The design details in the table above — welding, polish, piping, jackets, headspace — are the levers that make that half a per cent realistic.
Frequently asked questions
Does whirlpool design really change the taste of the beer?
It changes what reaches the fermenter. A sharp whirlpool leaves coarse trub behind so the beer clears faster with less harsh bitterness; a poor one carries solids over that show up as haze and tank losses.
What tank details should a buyer check besides volume?
Check 100% full TIG welded joints, polish accuracy of 0.4 microns or better, piping designed to avoid wort aeration, jackets on body and cone, and separately calculated cover headspace.
Put the hot-side details in the specification
Volume and price will dominate the first conversation, but the details that decide clarity belong in the specification: welding, polish, piping route, jacket coverage and headspace. Ask for the layout in 3D so the whirlpool draw-off and the pipe runs to the fermenter can be seen, and ask which control level prints a production record, because a repeatable brew needs a record to compare against. HGMC publishes a free 2D, 2.5D and 3D design service for space layout and vessel and piping design, equipment from 1 BBL to 100 BBL, and fermentation and bright tanks supplied alongside the hot side. Compare the published beer brewing equipment list and the brewery system families before fixing the vessel count.
Welding, polish, piping, jacket, headspace and material details above are taken from the manufacturer's own website at hgmcbrewing.com, read on 23 Sept 2026; the trub and recovery arithmetic is our own example with the assumptions printed beside it. Confirm the published specifications before ordering[1].