Second BIAB: something went wrong...

[willhyde]

And I think it was mostly user-error :unsure:

Did my first BIAB a few weeks ago and it didn't quite go to plan. Ended up being an ok beer, just a bit bland due to being over-diluted.

So today I thought I'd have another crack, as the wife's office is having a wee home-brew competition at the end of October. Went for an American pale ale. On the basis of the first BIAB, when I started with 30L of water and ended up with 26L of slightly-lower-than-intended-gravity wort to ferment, I started this brew with 25L, aiming to have 21L in the fermenter (and then finish with 19L into my corny).

This time, however, the urn decided to put out a full-noise rolling boil, and I somehow ended up with just 14L post-boil :blink:

I've realised that I need some way of measuring the volume once the wort's in the urn* as I don't know my start-of-boil volume, but the grain was fully drained until it had pretty much done dripping, and it all went into the pot. I had 5.1kg of grain, so there was perhaps 5L lost to the grain, but that still means I lost 6L in 75 minutes... sounds like a lot, anyone else get this much boil-off?

Anyway, I got 13.5L (after trub losses) into the fermenter, at 1.066 (target OG was 1.052). So I added some filtered bottled water until I hit 1.052, and ended up with just over 16L at my target gravity. I'm guessing I should end up with a decent beer, just not as much as I was intending.

But now I'm wondering what went wrong... is the urn capable of a rolling boil with 25L but not 30L (more of an angry simmer the first time)?

Or, given that I got X amount of sugar out of the grain, and resulted in 16.3L of target gravity wort, if I had started with more water would I have ended up with 21L of under-gravity wort?

Any other guesses (or correct answers) much appreciated.

Cheers,

Will

* I'm thinking either a rod of some description with marks on it, or maybe using a punch to make a series of pin-point dings in the side of the urn at 1L gradations... what does everyone else use?

 

[Rocker1986]

It'll probably take you a few batches to get your figures sorted, but does your urn have a site gauge tube thing on the front? Maybe try a "dry" run with just water to get an approximation of boil off rates. I have a Crown 40L urn which does have a site gauge tube, so I've just marked a few volume levels on that and written them on the urn next to it, this allows me to approximate the volume much easier. Generally I will start with 35ish litres of water and end up with 24 or 25 litres in to the FV.

 

[Screwtop]

Lets take a look ........... you started with 25L......... 5 odd litres would have ended up soaked up in the grist leaving a pre-boil volume of 20L. Seems you may have not made allowance for boiloff volume.

Your post boil volume of 14 litres means you boiled off 6 litres in 75 min. This (6/20/75*60) = 24% boiloff which is high, the boil only needs to be rolling just slightly, a good target rate is 10%.

What do you have the boiloff rate set to in your brewing software? In any case if your brewing software predicted a preboil volume of 20 litres you only need to water back at end of boil to 20 litres to meet predicted target preboil gravity.

Screwy

 

[surly]

Hey WillH,

Not willing to try and help with ALL your questions as I am pretty new too. But, I measure my volume via marks made in my stirring spoon. A steel ruler also works well. Add a known volume, dip spoon/stirrer, ruler etc so that it touches bottom in centre of pot. Mark it with a line and a notation of volume. Keep adding more water and new marks through a practical range.
Something to keep in mind is that hot water takes more space than cold..

 

[CosmicBertie]

I notched my plastic mash paddle at 5L increments.

 

[wbosher]

I use a steel ruler and keep a spreadsheet with the different volumes and where they correspond to on the ruler. I've also got it set up for 65C, 78C and 100C, as water will expand when hot. This way I can get an accurate reading at dough in, mashout and boiling volumes.

 

[1974Alby]

agree wth others re marks on a spoon...I BIAB in a keggle with a spiral burner, a typical brew starts with 37L water and 5kg grain...after a 90 min boil I end up with 20L in cube and a couple of litres of break material left behind. I think my boil off is about 16% which is high, but its consistent, so I just work with it.

 

[willhyde]

Cheers for all the responses... Screwtop - I deliberately didn't allow much for boil-off losses as I lost virtually nothing on the previous batch. I haven't really used software to date, but playing around with Brewmate and the BIAB spreadsheet off here, it seems I should have started with 31L more or less. Thing is, I started with 30L first time round and ended up with 26L in the fermenter. Seems extremely inconsistent, I guess the answer is to keep making more and more beer until I get it sussed :beer:

Ah well, at least I ended up with some wort at the target gravity, so it looks like I'll get some decent beer out of it. Still, if I'd had enough water to start with, and ended up with 21L in the fermenter, it seems it would have been under-gravity. Is that an efficiency thing? I don't sparge, just let the bag drain until it stops dripping and then give it a quick squeeze. Should I do a bit of a sparge to get more sugars out?

Is it better to try and maintain a slightly less rolling boil - probably by removing the insulation that I left on after achieving the boil - or aim to get the right amount of water to cope with high boil-off? Is there a benefit either way?

And as for the measurements, marks on my spoon sound sensible (and cheap).

 

[CosmicBertie]

Keep the insulation on to keep your boiling going. Adjust your water volume and grain amount to get your desired OG and fermenter volume.

Squeeze the hell out of the bag too, you'd be surprised just how much comes out. But keep brewing, making notes, asking questions and tweaking your process. You'll get there in the end.

 

[QldKev]

I've got a couple of rough marks on my 1V and also my 3V's kettle. I find they work a treat in seeing how you are going.

This is my 1V

 

[stm]

Strange that you got very inconsistent boil off. Shouldn't be too affected by volume at start of boil. What type of urn do you have? Was it a really cold day first time around?

As suggested above, a good squeeze in a large bucket is all that is needed. Don't worry about a sparge.

I have found that the BIABacus over on the "other website" is excellent at giving you the right starting point such as total water needed. 31L seems about right for 21L into the FV.

What I have found is the easiest way to measure volumes in the urn is to calibrate and mark a ruler with volumes measured down from the top lip of the urn. So touch the bottom end of the ruler to the top of the wort and read off the volume (using the marks you have written on the ruler) against the top lip of the urn. Very easy once you have calibrated and marked your ruler.

 

[wbosher]

What I have found is the easiest way to measure volumes in the urn is to calibrate and mark a ruler with volumes measured down from the top lip of the urn. So touch the bottom end of the ruler to the top of the wort and read off the volume (using the marks you have written on the ruler) against the top lip of the urn. Very easy once you have calibrated and marked your ruler.

This is a very simple and effective way of doing it provided your pot is level, or you could get a very different reading depending on where you take the measurement.

If you take it from the bottom of the pot, in the middle, it doesn't matter if it's not quite level, you'll get the same reading. This of course assumes that the bottom of your pot is flat.

EDIT: Also agree with the comment about the BIABacus, very nice spreadsheet.

 

[stm]

Good point! I'll get the spirit level out next time (laundry tiled floor might be not level!).

 

[wbosher]

I was referring mainly to those who maybe have a mobile set up on wheels, or perhaps out in the back yard or something. It doesn't take much to throw it out by a few liters.

 

[yum beer]

Cheers for all the responses... Screwtop - I deliberately didn't allow much for boil-off losses as I lost virtually nothing on the previous batch. I haven't really used software to date, but playing around with Brewmate and the BIAB spreadsheet off here, it seems I should have started with 31L more or less. Thing is, I started with 30L first time round and ended up with 26L in the fermenter. Seems extremely inconsistent, I guess the answer is to keep making more and more beer until I get it sussed :beer:

wouldn't be too concerned about the differences from batch 1 to batch 2.....
very obvious that on batch 1 you screwed your actual volume to start with. No way you started with 30 litres and got 26 in the fermenter......maybe an extra jug or 2 of initial water went in.
I know I use a 2 litre jug to transfer water to HLT and have miscounted on occasion.
Something to think about.

Put your known numbers from batch 2 into your software and see how you go on batch 3.

 

[stm]

No probs, wbosher. I set up near the drain hole in the laundry floor so there could well be a slope.

 

[willhyde]

wouldn't be too concerned about the differences from batch 1 to batch 2.....
very obvious that on batch 1 you screwed your actual volume to start with. No way you started with 30 litres and got 26 in the fermenter......maybe an extra jug or 2 of initial water went in.
I know I use a 2 litre jug to transfer water to HLT and have miscounted on occasion.
Something to think about.

Yeah, that occurred to me too, except I filled the urn using a plastic fermenter, which has moulded-in volume marks. Filled the fermenter (it only holds 30L) and tipped it into the urn, rather than losing count of jugfuls, so I'm pretty sure it was 30L...

Ah well, I got some drinkable beer from it so no great loss.

Put your known numbers from batch 2 into your software and see how you go on batch 3.

I think I'll follow your last bit of advice and treat the second brew figures as legit (or more legit than the first lot) and use them going forward.