Confused Re Stovetop Brewing!

[jkirky]

Gday all,

I put down my second AG by BIAB on my stovetop... It was a simple stout which i got from a recipe round the traps...

Well, in my first brew... I used a 4kg grain bill and ended up with 1040og with an 18 liter batch... I figured my efficiency was low (not sure the % though)

This brew, I used a 4.6kg grain bill and ended up with 1040og with an 18 liter batch...??? Again, im not sure how to calculate efficiency but i guess its low...

I was given some great advice after my first brew to pick up efficiency... One was to squeeze the bag. I did this with my last brew and also increase my water to grain ratio as well as my sparge temp.

I ended up with my preboiled liquor sitting about 10mm below the lip of my BIG-W 19 liter pot. So i guessed I had around 18.5 liters of preboiled wort. I took a gravity reading and it was 1045 at about 60 degrees. So it was looking like about 1065 or so after the temp adjustment.. I figured this would be great as I was planning on topping up to 20 litres which would drop the gravity to where i wanted it...

BUT after the boil and topping up to 18 litre mark on my coopers fermenter, the OG was only 1040 at 20 degrees?????

I am now starting to think my apparent efficiency issue is due to my water to grain ratio. I actually am questioning the actual capacity of my BIG-W pot. IE the pot was full with 1060 gravity liquid, but after the boil off, and tipping and topping up the fermenter to the supposed equivelent volume, the gravity has dropped?? Something isnt right...

I measured my pot and its 30cm x 25.5cm (external recordings)...

Any ideas? Please help!

 

[donburke]

Gday all,

I put down my second AG by BIAB on my stovetop... It was a simple stout which i got from a recipe round the traps...

Well, in my first brew... I used a 4kg grain bill and ended up with 1040og with an 18 liter batch... I figured my efficiency was low (not sure the % though)

This brew, I used a 4.6kg grain bill and ended up with 1040og with an 18 liter batch...??? Again, im not sure how to calculate efficiency but i guess its low...

I was given some great advice after my first brew to pick up efficiency... One was to squeeze the bag. I did this with my last brew and also increase my water to grain ratio as well as my sparge temp.

I ended up with my preboiled liquor sitting about 10mm below the lip of my BIG-W 19 liter pot. So i guessed I had around 18.5 liters of preboiled wort. I took a gravity reading and it was 1045 at about 60 degrees. So it was looking like about 1065 or so after the temp adjustment.. I figured this would be great as I was planning on topping up to 20 litres which would drop the gravity to where i wanted it...

BUT after the boil and topping up to 18 litre mark on my coopers fermenter, the OG was only 1040 at 20 degrees?????

I am now starting to think my apparent efficiency issue is due to my water to grain ratio. I actually am questioning the actual capacity of my BIG-W pot. IE the pot was full with 1060 gravity liquid, but after the boil off, and tipping and topping up the fermenter to the supposed equivelent volume, the gravity has dropped?? Something isnt right...

I measured my pot and its 30cm x 25.5cm (external recordings)...

Any ideas? Please help!

did you tip the entire contents of the kettle into the fermenter ? trub as well ?

 

[jkirky]

did you tip the entire contents of the kettle into the fermenter ? trub as well ?

After the boil, i topped up the kettle as close to the brim as I could with cold water than chilled in the kettle on my garage floor overnight...

Then this morning I tipped the contents into the fermenter MINUS the hot break material. This may have been about 500ml or so...

BUT THE FERMENTER READ ABOUT 14 LITRES! So my guess is that, just under the brim of the kettle, was 15 litres (which means my kettle aint the 19 litre i thought i bought) OR my fermenter doesnt tell a true reading of capacity...

something aint right! Maybe im loosing my mind!

 

[donburke]

After the boil, i topped up the kettle as close to the brim as I could with cold water than chilled in the kettle on my garage floor overnight...

Then this morning I tipped the contents into the fermenter MINUS the hot break material. This may have been about 500ml or so...

BUT THE FERMENTER READ ABOUT 14 LITRES! So my guess is that, just under the brim of the kettle, was 15 litres (which means my kettle aint the 19 litre i thought i bought) OR my fermenter doesnt tell a true reading of capacity...

something aint right! Maybe im loosing my mind!

the hot wort would contract when cooling, this may explain around 5%

you have losses in the trub, and this should be allowed for, maybe more than 500ml, so say 5%

you had the kettle say 95% full,

allow another 5% error in the fermenter markings,

all in all possibly 20%

so 19 litres less 20% = 15 litres

mythbusters say 'plausible'

 

[seemax]

After the boil, i topped up the kettle as close to the brim as I could with cold water than chilled in the kettle on my garage floor overnight...

I hope you have your bugs under control... and sprayed some no-rinse all over the lid and surrounds!!

Installing a tap on the pot really is worth the effort or buy a siphon so you can drain from the top and into a cube (read the no-chill process).

 

[RdeVjun]

Don't panic jk, I do this sort of stockpot/ stovetop BIAB/ over- gravity boil pretty well all of the time with no real hassle. (Well, it is a teensy bit of a PITA but I'm happy enough with it!)

First thing I'd say is your fermenter isn't reliably calibrated, that's a given as I've never come across one that is. When you've got that brew out of it, check it. However, I actually rely on the kettle volume, not the fermenter. (My kettle is very similar to yours, about 0.76 L / cm.) There may also be a wort shrinkage due to temperature issue, IIRC hot wort volume will shrink by about 4% when it is chilled to pitching temp, that's why no- chill cubes suck in when they're cooled.

I use excess sparge liquor to top the boil up as it progresses, so increase the sparge volume or even repeat it with the >4kg grainbill, with this caper, the fuller your stockpot is at all times, the better IMO. Add it gradually and the boil isn't interrupted, you should finish the boil with the kettle full.

As an aside, don't worry too much about hops utilisation with the over- gravity boil, but if you're really concerned, add 10% more IBUs per 0.010 over 1.050 (at pre- boil SG).

And finally, some would consider it cheating but I'll not be deterred, if efficiency is still a hassle then brew some sugar- friendly styles! ESBs are fine with it, stout is another. Belgians I haven't even looked at yet, but are another candidate.

BTW, kettle- chilling and topping up with cold at pitching is fine too, just needs to be sanitary. I do that a lot too.

Hope this helps! :icon_cheers:

 

[jkirky]

Don't panic jk, I do this sort of stockpot/ stovetop BIAB/ over- gravity boil pretty well all of the time with no real hassle. (Well, it is a teensy bit of a PITA but I'm happy enough with it!)

First thing I'd say is your fermenter isn't reliably calibrated, that's a given as I've never come across one that is. When you've got that brew out of it, check it. However, I actually rely on the kettle volume, not the fermenter. (My kettle is very similar to yours, about 0.76 L / cm.) There may also be a wort shrinkage due to temperature issue, IIRC hot wort volume will shrink by about 4% when it is chilled to pitching temp, that's why no- chill cubes suck in when they're cooled.

I use excess sparge liquor to top the boil up as it progresses, so increase the sparge volume or even repeat it with the >4kg grainbill, with this caper, the fuller your stockpot is at all times, the better IMO. Add it gradually and the boil isn't interrupted, you should finish the boil with the kettle full.

As an aside, don't worry too much about hops utilisation with the over- gravity boil, but if you're really concerned, add 10% more IBUs per 0.010 over 1.050 (at pre- boil SG).

And finally, some would consider it cheating but I'll not be deterred, if efficiency is still a hassle then brew some sugar- friendly styles! ESBs are fine with it, stout is another. Belgians I haven't even looked at yet, but are another candidate.

BTW, kettle- chilling and topping up with cold at pitching is fine too, just needs to be sanitary. I do that a lot too.

Hope this helps! :icon_cheers:

Just used an online volume calculator and my pot turns out to hold 15.5 liters...

Must have picked up the wrong one...

So 14 liters would be about right when my liquid was just under the rim.

BTW no probs with bugs when the kettle is sealed well, although it is a challenge (touch wood)

 

[dazadude]

Hey, just checked my 19L Big W pot. It's 32cm x 26cm.

Cheers, Daza.