Single Kettle BIAB Systems

Craft Hardware · Design Guide

Single Kettle BIAB Brewing

The simplest and most cost-effective way to brew all-grain beer

Brew in a Bag Kettle sizes: 40L · 60L · 85L crafthardware.de

Why We Recommend Single-Vessel Systems

After many years working with different 2- and 3-vessel brewing systems, the single-vessel recirculating system has become our preferred brewing setup for homebrewing. It offers a simpler layout, compact footprint, reduced plumbing complexity, and a more streamlined brew day process.

Well-designed BIAB recirculating systems allow for precise mash temperature control and highly repeatable results while requiring less cleaning and operational effort than many more complex multi-vessel systems.

This guide is intended for all homebrewers — from beginners to experienced brewers — who want to build a reliable and practical brewing system.

The examples shown are intended to illustrate typical single-vessel layouts and brewing workflows. Depending on batch size, heating method, and desired level of automation, component selection and system layout may vary.

BIAB (Brew in a Bag) is an extremely cost-effective way to brew all-grain beer while keeping your equipment as simple as possible. These single-vessel, non-recirculating systems stand out for their simplicity and low entry cost — one kettle, one bag, one heating element, and you are brewing.

Fill the kettle with your full mash volume, heat to strike temperature with the built-in element, switch off the heat, lower the brew bag and stir in your milled grain. Close the lid and wait approximately 60 minutes for the mash to complete — occasional stirring helps. Pull the bag, switch the element back on to reach boiling temperature, add hops per your recipe, then cool to pitching temperature using your preferred method. That is the whole process.

The Craft Hardware bottom-drain kettle is well suited to BIAB. The bottom port means the kettle empties completely without tipping or scooping, and the Tri-Clamp connection system makes it straightforward to expand the setup later if you decide to move to a recirculating system.

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Grain capacity and bag lifting The maximum grain bill is limited by your ability to lift the bag out of the kettle. We strongly recommend installing a pulley anchor point directly above the kettle before your first brew. A block-and-tackle pulley makes lifting a heavy, wet grain bag safe and manageable for one person.

Batch Sizes by Kettle

The figures below assume a 60-minute boil at 13°Plato original gravity. Extract efficiency (Sudhausausbeute) for BIAB without sparge is typically 52–58% for German brewers. Maximum batch size decreases for higher gravity beers.

Kettle	Min. batch size *	Max. without sparge **	Max. with sparge **	Boil volume range ***
40L	13 L	26 L	31 L	16 L – 34 L
60L	17 L	39 L	49 L	20.5 L – 53 L
85L	23 L	57 L	72 L	27 L – 76 L

* Volume including hot break. At the end of the boil, the heating element sits approximately 6 cm below the wort surface. For very small batches, reduce element power using a compatible brew controller or voltage regulator.

** 60-minute boil, 13°P original gravity, volume including hot break. For higher gravity beers maximum batch size reduces accordingly. Note that using a steam condenser reduces maximum batch size further.

*** Includes a 6 cm safety margin between wort surface and kettle rim. At maximum volume, take care to prevent boilovers — anti-foam agent may be required.

Process Notes

Strike Temperature

The kettle element heats water faster than it heats a full mash. Set your initial strike temperature approximately 2–3°C above your target mash temperature to compensate for the cooling effect of adding the grain. Switch the element off before adding grain — never mash with the element running, as it will create hot spots directly on the grain.

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Always switch the element off before adding grain The element surface temperature is far higher than the water temperature. Grain in direct contact with a running element will scorch, producing harsh, astringent flavours in the finished beer.

Mash Stirring

Unlike a recirculating system, BIAB relies on manual stirring to distribute heat and ensure even conversion. Stir well when adding grain to eliminate dry clumps, then stir every 10–15 minutes during the mash. Remove the sparge arm spreader plate before stirring to give yourself full access to the grain bed.

Bag Lifting

A saturated grain bag is considerably heavier than it looks — plan your lifting solution before brew day. A pulley anchor point directly above the kettle, combined with a block-and-tackle pulley, allows you to lift the bag safely and let it drain fully before removing it. Allowing the bag to drain for several minutes over the kettle recovers a meaningful volume of wort and improves efficiency.

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No-sparge vs. sparge BIAB can be brewed with or without a sparge step. Without sparging, the full water volume goes into the mash — simpler but lower efficiency. With sparging, you rinse the grain with additional hot water after lifting the bag, which improves efficiency and allows slightly smaller mash volumes. The batch size table above shows both options.

Boil and Hop Additions

Once the bag is removed, switch the element back on and bring the wort to a vigorous boil. Add hops per your recipe schedule. A 60-minute boil is standard; shorter boils are possible with high-alpha hops or pre-isomerised hop products. At flameout, cool the wort to pitching temperature using a counterflow chiller, immersion chiller, or ice bath.

Electrical Safety

Craft Hardware heating elements are sold unwired. All electrical connections must be made by a licensed electrician before use. Every heating element circuit must be protected by a GFI/RCD breaker. Do not attempt to connect an element to mains power yourself.

Bill of Materials

The following components are required for a complete single-kettle BIAB setup. Quantities marked vary by kettle size.

Qty	Component	Size notes
1	Bottom-drain kettle	40L, 60L, or 85L
40L / 60L: 1× 85L: 2×	Heating element 3.2 kW Tri-Clamp	Sold unwired — professional installation required
40L / 60L: 1× 85L: 2×	Connection cable 3m H07RN-F 3G1.5	For electrician use — one per element
1	BIAB Brew Bag	Sized to match your kettle
1	40L / 60L: BIAB pulley 85L: BIAB pulley — heavy duty	Essential for safe bag lifting
1	BIAB ratchet strap	For securing the bag during draining
1	40L / 60L: Hose clamp 16–27 mm 85L: Hose clamp 25–40 mm	For kettle drain hose
~0.5 m	40L / 60L: Silicone hose 14 × 24 mm 85L: Silicone hose 19 × 30 mm	For kettle drain connection
1	40L / 60L: 90° hose barb Tri-Clamp 1.5" × ¾" 85L: 90° hose barb Tri-Clamp 1.5" × 1"	Angled barb for easy hose routing from bottom port
1	Butterfly valve DN40 Tri-Clamp with lever handle	Kettle outlet shut-off
10	Silicone gasket Tri-Clamp 1.5" × DN40	Spares included — inspect and replace as needed
6	Tri-Clamp clamp 1.5"	Hand tight only — do not overtighten
40L / 60L: 2× 85L: 1×	Blind cap Tri-Clamp 1.5"	For unused ports
1	Bimetal thermometer Tri-Clamp	For mash and boil temperature monitoring

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Controller A brew controller is optional for BIAB but useful. It allows precise mash temperature control and can reduce element power for small batches where full power risks a boilover. A basic single-circuit PID controller is sufficient.

Growing Beyond BIAB

BIAB is an excellent starting point — and a complete brewing system in its own right. Many experienced brewers continue with it indefinitely. But if you find yourself wanting higher efficiency, larger batch sizes, or more process control, the Craft Hardware kettle range is designed to grow with you.

The natural upgrade path

Your BIAB kettle does not become obsolete when you upgrade. It becomes your Brew Kettle. Add a second kettle as an MLT and a third as an HLT, and you have the foundation of a full 3-kettle HERMS system — using the same Tri-Clamp fittings and silicone hose you already own.

Read the 3-Kettle HERMS Build Guide when you are ready to take that step.

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