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Quotes - Engineering - SalesBrewhouse knockout
A fixed-time job with three temperatures to hit
Wort leaves the kettle or whirlpool at 205 to 212 F and has to arrive in the fermenter at 50 to 55 F for a lager or 65 to 68 F for an ale, in the time the brewer allows for knockout. Everything in between, 160 F where wild organisms wake up, 140 F where dimethyl sulfide stops leaving, is passed through as fast as the exchanger allows.
The chiller is a gasketed plate exchanger with two sections on one frame, and this page is about sizing it: flow from the knockout time, the water and glycol split, the hot liquor it makes, and cleaning.
Sizing a wort chiller from the knockout clock backward
Flow from the batch and the knockout time
A brewer decides how long knockout takes; the chiller has to keep up. A 30 barrel batch is 930 gallons, and at a 45 minute knockout that is about 21 gpm of wort. A 100 barrel brewhouse on the same clock is 69 gpm. Cutting knockout to 30 minutes raises the flow by half and the area with it; that decision has more effect on price than anything else on the sheet.
The chiller is also the constraint on how many brews a day the house can run. Three brews a day needs a faster knockout or a second chiller, and a liquor tank that holds what the first knockout makes.
Two stages: water then glycol
The first stage on brewing water takes the wort from 212 F down to about 10 to 15 degrees above the water inlet, so 70 to 80 F on 60 F water, and heats that water to 170 to 180 F. That water is the next brew's strike and sparge liquor, and the exchanger is sized so the water flow that produces 175 F liquor is close to the wort flow, at a ratio of 1 to 1.2. The second stage on glycol at 28 F takes the wort the rest of the way to pitching temperature with a 5 to 8 degree approach.
Both stages sit in one frame with a connection plate between them and separate ports for water and glycol. The cold break forms in the glycol stage and settles in the fermenter. Above about 5 barrels, one stage on glycol alone wastes refrigeration on heat the water would have taken for free and gives the brewhouse no hot liquor.
Hop resin, trub and the gasket pack
Wort after the whirlpool still carries hop resin and fine trub, and both settle on the plates in the first pass where the wort is hottest. The plate pattern is chosen for a wide enough channel that hop fines do not bridge, the velocity is kept at 1.5 to 2 ft/s, and the frame opens with a few bolts so the plates can be inspected.
The CIP is caustic at 160 F after every brew day, an acid step weekly for beerstone, and a sanitizer immediately before knockout, because the chiller is the last thing the wort touches before the yeast.
The common mistake
Buying the chiller for today's brewhouse and the fermenters for next year's. A 15 barrel chiller on a 30 barrel kettle knocks out in 90 minutes and the lager picks up a corn note. A frame can take more plates, so buy the frame for the biggest kettle the building will hold and the plates for today. Send the batch size, the knockout time, the water temperature in summer, and the glycol temperature. Call and talk it through with an engineer: 1-805-484-2992
Wort cooling process conditions
A knockout is a fixed-time job, and the rows show the temperatures, utilities and plate arrangement a brewhouse chiller is sized to. Compare them with your kettle and send the batch size and knockout time.
| Condition | Detail |
| Product | Boiled wort, 10 to 20 Plato, 1 to 3 cP hot, with hop and trub fines after the whirlpool |
| Flow range | 10 to 300 barrel batch divided by a 30 to 60 minute knockout; 8 to 300 gpm |
| Temperatures in / out | 205 to 212 F in; 50 to 55 F lager or 65 to 68 F ale out |
| Hold | None; shortest possible time between 160 F and pitching |
| Utility | Stage one: brewing or city water at 50 to 65 F. Stage two: propylene glycol at 26 to 30 F |
| Approach | 10 to 15 degrees on water stage; 5 to 8 degrees on glycol stage |
| Construction | Two-section gasketed plate on one frame with a connection plate between; 316L plates; EPDM gaskets |
| Finish / class | 316L, 32 Ra; food-grade drainable; 3-A plates where specified |
| CIP | Caustic 2 percent at 160 F after every brew day, acid weekly for beerstone, sanitizer before knockout |
Common FAQs
In one pass over a 30 to 60 minute knockout. The critical band is 160 F down to pitching, where wild organisms grow and DMS stops driving off; a plate chiller passes each gallon through it in seconds.
For an ale at 65 to 68 F on 50 F water, yes, with a 15 degree approach; the glycol stage sits idle. Lagers at 50 to 55 F need the glycol stage in every season.
170 to 180 F at a water-to-wort ratio of about 1 to 1.2. Throttling the water to make hotter liquor slows knockout and drops the wort outlet warmer into the glycol stage; the exchanger is sized so the brewer does not have to choose.
Hop resin and trub bake on the hottest plates and beerstone builds over weeks. Caustic daily, acid weekly and a sanitizer before knockout keep the chiller from being the brewery's infection source.
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