Double Batch Noob Question

[Hefty]

I did a quick search to find out if amount of trub increases proportionally for a double batch or if it is more, or less, proportionally than for a single.
Only one post had much to say and suggested that it's only 20% more for a double. However, this was based on the experience of only one brewer.
So, what's the consensus? What do you find with your setup?
I'm about to do my first double to split with my brother and I'm just after a rough guide in case I need to up my volumes to compensate.

Cheers!
Jono.

 

[cdbrown]

Not sure about trub but make sure to take into account the lower efficiency of the brewhouse when doing double batch. Say 5% less.

Are you fermenting it all in a 60L fermenter? If it's split into two fermenters then you'll get pretty much the same amount of trub as a normal batch in each fermenter. I try to end up with 19L post ferment so allow 2L for each fermenter (which suits the cube nicely) so 42L out of the kettle + any losses due to kettle muck of about 1L or so.

 

[murrayr]

why do you get lower efficeincy for double batches?
since i started doing double batches my efficeincy has been higher than ever (pushing 80%).
don't mean to change the subject sorry. so on topic; as cdbrown mentioned if you're splitting it into 2 fermenters it won't make a difference. now thinking about it, fermenting in my 60L fermenter i have had a proportional increase in trub. that is twice as much as there would be for a split batch.
murray

 

[cdbrown]

I've read and been advised a few times that efficiency generally drops by 5% when doing double batches. I've only done one double batch so far and a few singles on this new rig so my efficiencies are all over the place.

 

[murrayr]

i couldn't imagine why efficeincy would drop with larger batches.
is it assuming its harder to get a consistent temperature through the mash or...?
i've done about 6 double batches and it's been as good as (at times better than) ever.
if there is a difference would triple batches be worse still?

 

[cdbrown]

Perhaps it's due to limitations of the mash tun in terms of size? I have to add 10L of water at the end of the boil as I wouldn't be able to put enough in the 50L kettle pre-boil. Perhaps I could do a 2nd sparge with 15L and drain that to a pot, boil that for 60mins leaving 10L of wort to add to the main batch.

 

[murrayr]

oh ok.
i was assuming the size of the equipment was growing relative to the batch size (i'm using a 66L kettle and mash tun).
i suppose if that's your method you probably would lose a bit of efficeincy.
having too small a mash tun would mean a low water to grist ratio which would have less yeild, but that's not something that's inherit with upgrading to double batches.
cheers, murray