Using a 40L Electric Urn for BIAB - a guide
This article is a re-write of one from about 7 years ago that ended up in the Partials sub forum.
INTRODUCTION
40L electric urns are now widely used, as they lend themselves to Brew in a Bag (BIAB), an All Grain method that was largely developed and refined in Australia.
The popularity of BIAB derives mostly from its being a 'one pot' method with no need to buy and operate three separate vessels with associated plumbing and in many cases pumps etc.
Many BIAB brewers have taken this method one stage further by using an electric urn, thus doing away with the need to buy gas bottles and burners or the need to drill or modify a large stockpot or a keggle. Add a brewing bag or voile sheet and the 40L urn is virtually a 'turn-key' brewery ready to go out of the box. It remains the the cheapest ready-made electric brewing solution and has produced award winning brews.
Here's a points summary of BIAB using a 40L urn so we know what we are going to cover in this guide. Then a fuller description of the necessary equipment and a walk through of the process.
It's assumed that a “standard” 23L brew is happening here using a 40L urn.
Heat 30 to 35 litres of water (liquor) to strike temperature, around 2 to 3 degrees hotter than the desired mash temperature.
Turn off the power to the urn
Fit a bag or circular sheet of Swiss Voile large enough to completely fill the urn
Quickly and thoroughly stir in the grain bill and put the lid on.
Insulate the urn to keep the temperature steady during the mash.
Remove the insulation and raise the bag to drain the wort back into the urn.
Bring to the boil, dispose of the spent grain.
Add hops, using a hop sock or hop bag if required.
Add kettle finings at the end of the boil.
Raise hopsock if you used one, put lid on urn and allow to boil just long enough to sterilise the head space, then switch off the power to the urn.
Leave for around 20 minutes for the trub to settle to the bottom of the urn, then run the clear wort into a chiller or a no-chill cube.
There are two main brands of urn available in Australia, Birko and Crown. In recent years Buffalo urns from the UK have appeared and other lesser known brands pop up on E bay.
Crowns are priced from $270 to $295 (March 2016) from our forum sponsors which represents excellent value; they haven't gone up much in the last 7 years. Best to buy from forum sponsors, or a local hospitality warehouse if they have good deals on.
Birko is a good urn, but Crown seems to be the most popular nowadays, since issues with the concealed element cutting out were fixed. They have consulted with home brewer suppliers to make their product more suitable. As with Birko, an exposed element model is available. Jury is still out on which is best for brewing. Personally I'd go the concealed element nowadays for ease of cleaning.
Buffalo urns have a following in the UK and they report good results. Now available from Australian suppliers.
Some brewers acquire 30L urns. Single Volume BIAB is possible but a sparging step might be needed due to the smaller volume of these urns. Not covered here, but not difficult, it just requires a source of sparging water and a collecting vessel such as a nappy bucket.
Bag
Swiss Voile is the most popular material, it's a thin light polyester curtain material available from Spotlight, about $15 for enough material to make a bag. Birko urns are a bit shorter and wider than Crown urns so I won't offer exact measurements, but the best bag design is exactly like a can of baked beans with a circular bottom section. This will hang like a teardrop on hoisting.
I use a hemmed circle of voile that's almost indestructible and dead easy to empty and clean, but bags still have their followers. Available ready made from online HB suppliers. I'll just use the term “bag”.
Hoisting the Bag
A “skyhook” and pulley system is a cheap and effective way of hoisting the bag. Many strapping young brewers are put off by the difficulty in pulling out and draining a heavy scalding hot bag.
A double pulley setup can be made cheaply from bits from hardware stores. My 81 year old lady friend who had a stroke can raise it with one hand.
Here's a threading diagram, if your upper “block” doesn't have a ring at the bottom, called a “beckett” then just attach the fixed end of the cord (the opposite end of the cord to the end you pull on) to the rafter or whatever you are hanging the hoist from. This does the same job.
Here's my setup.
Now see what I've done here: a small SS hook attached to a hangman's noose.
So after throttling the bag with the noose, just attach the hook to the bottom ring of the pulley block and hoist. To dispose of the grain simply unhook the bag and take it away.
On hoisting, the cord can be tied off and the bag left to drip at its own pace while the wort is raised to the boil.
Learn to do a hangman's noose until you have it down pat, it's the most useful knot for BIAB and I use it for everything as you can see from the photos.
Other Equipment
Most of the below is common with other methods of wort production but are here is a checklist:
Depending on which methods you use, you may not need all the items. I have not gone into No-chill equipment, which is not part of BIAB although a popular method, except to say that whatever cooling method you use, replacing the urn tap with a ball lock tap will enable you to fit a silicone hose which is difficult to do with the 'native' urn taps.
Urn
Extension Cord
Bag
Mash Paddle and spoons
Timer
Rack to keep bag off the urn element
Accurate 'stick' thermometer
Scales accurate to 1g
If using a skyhook: Awning rope, pulley
If passive lagging: Sleeping bag, doonah
Circle of bubble wrap same diameter as the urn
Refractometer or hydrometer to check wort gravities
Gardening gloves or heavy duty rubber gloves
This will get you brewing grain beers and set yourself free for less than $400 (excluding fermentation side gear), if you shop around and no doubt you will have many of these items already if you are brewing using other methods.
METHOD
Prepare the strike liquor
It is essential that you have a good thermometer, an electronic probe kitchen style thermometer is ideal for mashing. I don't fiddle with the temperature knob on the urn, I just leave the urn dial on maximum all the time.
Most 5% brews will require about 33L of strike liquor. A good brewing software such as Beersmith or Brewers Friend will help you fine tune this.
Check grain temperature
While the urn is heating I add any water salts and check the temperature of the milled grain I am going to mash. As a rule of thumb I allow three degrees hotter strike water than the starting mash. So if I'm aiming for a mash at 66 I would generally heat the strike liquor to 69. Give the liquor a good stir so you aren't measuring the temperature of a convection plume.
However, grain temperature can alter this by up to a degree. Check your brewing software to see if it has a strike temperature calculator that takes grain temperature into account. Brewmate and Beersmith have this feature, which is handy for cold weather.
Avoid the bag coming into contact with the element
If you intend to do step mashes or a mashout, you'll obviously need to keep the bag away from the element.
A good piece of kit is a curved roasting rack that you'll find in most upmarket kitchen shops. Preferably SS, around $15
Attach a length of brickie's twine to the rack so you can fish it out after mashing.
Fit the bag
Switch off the power, lower the bag and clip it round the edges of the urn with clothes pegs. Some commercial bags have a drawstring or are elasticated.
Dough in
Add the grain bill in a thin stream and stir constantly with a large spoon to avoid doughballs. Then give the mash a good up and down rousing with a metal paint stirrer or a good stir with whatever other mash paddle you have on hand.
Cover and lag
If you float a circle of bubble wrap on top of the mash (bubble side down) then put lid on urn, this will stop most heat escaping through the lid.
After using several methods over the years I find that a cheap $12 doonah from Big W makes a very good insulator, just wrap around and secure loosely with a bungee cord or two.
You should get about one and a half degree per hour drop in temperature, which is more than acceptable as most saccharification will take place in the first half hour. Some BIABers have their urn permanently lagged with cut-up camping mat but still wrap with extra insulation while mashing.
I normally do 60 min mashes with simple infusion mashes.
Step Mashing
BIAB in an urn is an ideal system for doing step mashes very easily, and is one of the clear advantages over 3 vessel brewing.
It's simply a case of turning on the power and ramping up the temperature between rests whilst occasionally pumping up and down with a suitable mash paddle and of course keeping a close eye on temperature. During each rest, the urn is re-lagged.
Popular step mashes include the Hochkurz mash as used in Germany:
62 degrees for 40 mins (Saccharification rest), 72 degrees for 40 mins (Dextrin rest) then 78 degrees for 10 mins (Mashout).
The final step, mashout, is easy with BIAB in an urn because you are going to heat the wort to boiling point anyway, and for mashout you just let the mash go along for the ride on the way up.
Specific Warning on protein rest.
If, as part of a step mash, you want to try a protein rest at around 52 degrees you will have to do it with a thicker mash, then step up to over 60 degrees by using boiling water to bring up to your desired mash volume. Then let it rest for a while before ramping further.
At low temperatures there will have been little conversion of starches to sugars and if you switch on the urn at this point you are likely to burn starchy “flour” onto the element causing scorching, blackening of the element and a complete cut out.
Hoist the bag
BIAB being a simple and quick method, the temptation is to say “how easy is this” then pull the bag out as quickly as possible.
This can result in a lot of turbulence and junk ending up in the wort.
Whilst a firm filtering grain bed does not form in the bag in the same way as a system such as Braumeister or HERMS, it is easy to form a quite practical and good-enough grain bed in the bag by very gently lifting while the wort is ramping up to the boil – there is no reason to hurry.
That's one reason a skyhook and pulley system is so good, I've recently started gentle lifting and getting far less trub in the urn after boil.
Don't forget to fish out your rack from the bottom of the urn.
Once the wort is running crystal clear out from the bottom of the bag, a firm squeeze, starting at the top of the bag, will retrieve the maximum amount of wort.
There are dedicated squeezers and dedicated non-squeezers. Up to you.
Boiling
With BIAB there is nearly always more turbid matter in the boil than with systems such as HERMS or Braumeister. A good way to keep turbidity down is to use a hopsock or hop spider. In my case I peg a grain bag right around the top of the urn and let hops flowers and pellets have their own “swimming pool”.
The grain bags sold by CraftBrewer, as well as paint strainer bags from decorator shops, retain most of the hop material including pellets but give perfect extraction as the steam and boiling has to go up through the bag while boiling.
The hop bag can be throttled and hoisted as well, to drain completely at the end of the boil.
The jury is out on whether turbid wort in the boil is better than clearer wort, but that aside, it's a fact that trub robs your volume of beer and costs money in the long run.
At the end of the boil
Don't forget Kettle Finings such as Whirlfloc.
Brewbright or Brewbrite is a newish kettle fining that also reduces chill haze in the finished beer.
When finished, remove hopsock and put the lid on the urn then move quickly to the wall socket and keep an eye on the urn, you will see some plumes of steam shooting out of the nostrils on the lid. Then switch off before the wort rises and foams out from under the lid. This should have nicely sanitised the headspace so you can safely leave it for about twenty minutes by which time the break and shyte will have settled right out.
You should get nice clear wort out of the urn. Any excess can be run into lab jars and allowed to settle out to add to the FV, use as starters etc.
BIAB's work is done.
Happy Brewing
Bribie G, March 2016
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