The benefits of electrical brew-in-a-bag systems
Electric brew-in-a-bag and single-vessel systems mash, lift and boil in one kettle. Here is why homebrewers like them and how they compare with three-vessel setups.
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The short answer: electric brew-in-a-bag (BIAB) and single-vessel systems mash, lift the grain and boil in one electric kettle. A pump recirculating through the grain basket holds the mash temperature, the controller handles step mashes, and there’s only one vessel to clean. Efficiency runs a little below a three-vessel system, but the brew day is shorter and simpler.
| Single vessel (electric BIAB) | Three vessel | |
|---|---|---|
| Space | One kettle | Three vessels and a stand |
| Brew day | Shorter | Longer |
| Mash control | Recirculated through the basket | Recirculated (HERMS or RIMS) |
| Efficiency | Good, a little lower | Highest |
| Back-to-back batches | One at a time | Easy |
Retro BIAB: where it all started
BIAB is a great option for any homebrewer, new brewers and veterans alike. If you’re ready to step up from brewing with extract, or you’re looking to downsize and simplify your brewing system, there are a lot of advantages to going the BIAB route.
I used to brew with a traditional three-vessel brewery. I invested a lot of time and money into my system, in fact. But after all that, I’ve realized that the BIAB method is preferable. You can get exactly the same flavour profile from a BIAB system as you can from the most expensive professional brewing systems on the market. BIAB systems are smaller and easier to set up. Less equipment means less expense. They take up less space, and some don’t even require changes to your household wiring. And as long as you’re using a bag made of nylon, which is inert and non-leaching, you don’t need to worry about steeping it in the hot wort.
But for me, the biggest advantage of BIAB is the time savings. Where a brew day can take eight or nine hours with a three-vessel setup, you can have your BIAB brew done and in the fermenter in under four.
Getting your efficiency up
There is a widely held belief that the trade-off for all of these advantages is reduced efficiency. With a three-vessel brewery, where you’re fully rinsing your grains, you can reach an efficiency of up to 90%. With the traditional brew-in-a-bag method you’re only going to get about 65%. But these tips will get your efficiency up to at least 80%, which means you only need to make up a 10% loss by buying a little extra base malt. Using them, I’ve been able to get as high as 89% mash efficiency.
- Crush fine. You’ll get your biggest gain from a super fine crush. I ask my local homebrew shop to double-crush my grains. Some people worry that crushing too fine will put excess tannins in the beer, but tannins come mainly from a high mash pH and water well above mash temperature, not from the crush, so a normal mash won’t extract them. With a pump recirculating through a basket, don’t go quite this fine: a very fine crush packs the grain bed and slows the flow. See improving mash efficiency for the crush we recommend there.
- Mash longer. Your second biggest gain will come from mashing for 90 minutes instead of 60. This makes sure you get full conversion.
- Rinse the grain. For a few extra gravity points, heat a large pot of water on the stove to mash-out temperature, 168°F (76°C). After you’ve lifted the grain out, put it in a bucket or pot that can hold the basket, rinse it with that water, and pour the rinse water into the boil. It gets the most volume out of a small system and can raise your efficiency by up to 10%. Don’t forget to subtract the rinse water from your strike volume.
- Squeeze the bag. I usually leave the bag in the mash basket, prop the basket over a pot and press it with a large spoon. Whatever you squeeze out at the end is denser and more concentrated, so it’s worth the effort.
Managing the mess
Aside from efficiency, the only downside to BIAB is that it can be a bit messy. That’s easily fixed if you prepare before you start.
- Protect the bag. Use a system with a basket or a mash screen over the element. You don’t want to melt through your bag.
- Plan the lift. On a bigger batch, you’ll be lifting a scalding hot bag of wet grain that can weigh upwards of 25 lb (11 kg). If you can’t lift it safely without spilling wort, install a hoist. Keep a 5 gal (19 L) bucket close at hand, or set up beside the sink and drop the bag in there to cool. Be careful: the hot grains can scorch you.
From bag to basket
Our Unibräu takes the same one-vessel idea and swaps the bag for a stainless grain basket. You mash, sparge and boil in one kettle, and the included pump recirculates wort through the grain to hold the mash temperature. The 10 gal size comes in 120V or 240V; the 20 and 30 gal sizes are 240V. The Unibräu All-In goes one step further: brew, chill, then pitch yeast and pressure-ferment in the same vessel.
Frequently asked questions
Is BIAB efficiency really lower?
A little, out of the box. A fine crush, a longer mash, rinsing and squeezing close most of the gap.
Bag or stainless basket?
A bag is cheap and fits any kettle. A basket won’t tear or melt, and it lifts out in one piece.
Can I step mash in a single vessel?
Yes. With a recirculating pump and a controller, you raise the setpoint for each step. See step mashing explained.
Do I need a 240V outlet?
No. A 120V system plugs into a standard outlet and suits 5 gal batches; 240V heats bigger batches faster.
120 V or 240 V? Compare heat-up times and find the breaker and outlet you need with our free electric brewery calculator.
Related guides
Electric brewing for beginners, no-sparge brewing, step mashing and improving your mash efficiency.