Someone has to ask, did you bring it to the boil before adding the malt?
I see someone has just as I started typing. Its a good question and the way it reads.
If you aren't getting a sensible boil it might be a good idea to meter the element (measure the resistance) low cost elements might say they are 2400W but are often a lot less and occasionally a lot more.
If you cant get a good boil in 15L I would be thinking seriously of talking to the supplier.
This is something I wrote a few years ago, it was designed for use with a 40L Birko urn, you might need to do some adjustments for batch size but the process should be fairly compatible.
Basic step by step guide to “Brew In A Bag” (BIAB)
The aim being to achieve a “standard” 22.5 L brew into the fermenter.
All of the water for the brew goes in at the start
We have the 22.5 L we want, the grain will absorb about 0.85 L/Kg, there will be a loss under the tap of 2 L, this is full of rubbish called Trub, evaporation will be about 10% of the start volume.
So we need 22.5 + 2 + (5.17 X 0.85) plus 10% or about 29 L plus evaporation roughly 3 L
- Add 32 L of water to the urn
Heat the water to the mashing temperature plus a degree or two as you get close stir well and measure with a thermometer. Consult an online metric “Strike Water Calculator” to get the exact temperature.
- Heat to 66-67oC (as per calculator)
The bag is now inserted into the Urn it acts like a liner and folds down over the outside.
The grain is now filled in, this should be done in stages with some gentle stirring to insure even mixing of the water and the malt, this is called mashing in.
Wrap the urn in some good insulation, old blankets, doona, foam or whatever is available and allow to stand for the time on the recipe (usually 1 hour), this is where the enzymes act on the starch and make sugars and it’s called Mashing
At the end of the Mash, the bag is lifted up and allowed to drain, there are several approaches to this step personally I put an A frame ladder on the table straddling the Urn; gather the bag and tie it with a piece of rope (sheep bend is the best knot); use the rope running over one of the rungs to hoist the bag. Liquid in the mixture of malt and water in the bag will drain back into the urn leaving the expended grain behind.
Once the bag is clear of the urn and draining turn the heat on to full. The bag will continue to drain for some time, try to resist the temptation to squeeze the bag. There is a lot of condensed protein mixed with the grain, squeezing can cause more of them to end up in the Urn which will make more Trub and can reduce the quality of the beer. It’s fine to leave the bag over the Urn for most or the entire boil. Do Not
fit the lid during the boil
Ones the boil is well established its time to add the first hop or bittering hop addition, the timing varies from recipe to recipe usually it’s 60-90 minutes, make a note of the time and plan for later additions, I use a simple countdown timer to remind me.
0-20 minutes from the end of the boil there may be other hop additions, these and the time of their addition are listed on the recipe. Loosely these are referred to as Taste additions that give Hop Flavour and later ones called Aroma Additions
- Make Taste and Aroma Additions as per recipe
5-10 minutes from the end of the boil we add Clarifying Agents these are available in many forms but all act to help Trub (rubbish) to settle faster, these are called Kettle Finning.
At the end of the boil, check that the right volume is left, this will be 22.5 L plus the 2 L that will stay in the Urn, if it’s a bit under adjust the volume with Boiling Water
make a note of any adjustments, this information can be used to adjust your next brew, if your evaporation is higher or lower than anticipated make adjustments to the start volume next brew.
- Check Volume is 24.5 -25L
To help all the trub collect in the bottom of the Urn we Whirlpool, this is simply stirring briskly to establish a good rotation of the body of the brew, natural vortex action will cause the Trub to collect in a cone at the centre of the urn. Avoid excessive splashing you don’t want to stir air into the brew.
Fit the lid and allow the brew to rest for around 10 minutes, this gives time for all the Trub to sink to the bottom; we then drain down in to a Cube. The wort must be hotter than 80oC and ideally at around 90oC. The heat will pasteurise the contents of the cube killing any bacteria. The cube should be as full as possible, have the lid fitted securely and then laid on its side; this is so the most convoluted parts of the cube are exposed to sterilising heat. After 10-15 minutes turn the cube onto the other side insuring all the surfaces get good exposure to heat.
Leave until cool, this generally takes a day or so, because of the natural sterilising the brew can be kept in an unopened cube for up to a year.
When you are ready to ferment, simply pour the contents of the cube into your fermenter, add the yeast, any hops that are listed as Aroma or dry hops can be added to the fermenter, these additions will be in a T-Bag, ferment as usual.