Double up for same results?

[gunner]

If i double up the ingredients for a 23L GW clone,will it produce the same outcome for 46L,I know it sounds a self explanatory question but thought i better check before brewing this volume.

Regards Graham.

[vacant]

Hang on, I'd have thought if you double the liquor you don't double your dead space and you'll lose the same, not twice as much, to evaporation during the boil?

[Parva]

Hang on, I'd have thought if you double the liquor you don't double your dead space and you'll lose the same, not twice as much, to evaporation during the boil?

You are quite correct. However, at that sort of volume the difference in the final SG will be minimal and not worth worrying about. I'm sure many of us have aimed for a final quantity of 23l and only got 21l. If you really know your system then by all means cut down on the loss to hops, trub and boil-off but for most of us just doubling the figures is good enough to get very close.

[gunner]

Thanks for your replies.
The last brew i did was batch sparged but made the mistake of subtracting the mash liquor from the total liquor,so was short on brewlength,rather than adding the mash liquor to total liquor to be treated.

So if using a GW 23L recipe that calls for total liquor =33L Mash liquor=11.8L total water to be treated before brewday =44.8L

So to double the final brewlength to 46L you would double the total water to be treated to 89.6L

But when i put my detail into jims batch sparge calculator im getting only 70L to be treated.
(TG bill 4.730kg= 23L)
Vol req for FV=46L boil loss= 15% loss to H&T= 3L TG Bill= 9.5kg Dead space MT= 2L Water/grain ratio= 2.5kg/L

wort for boil 57.6L
made of 2 equal batches of 28.9L
batch1# 40.4L =mash vol 23.75L top up 16.65L
batch 2# 28.9L

Im a little confused, could somebody have a look at my figures and see where im going wrong.Even if i double my dead space in mash tun and boiler im still only getting total liquor of 74 L.

[Barley Water]

Well, maybe I am just not understanding some of the comments on this thread but here are a couple of things to think about. First of all, extract efficiency in my experience is not quite linear. I almost always get worse efficiency as the size of the grain bed increases so if I am doing a bigger batch I adjust for that. I suspect it has something to do with the geometry of my mash tun (I use a coverted cylindrical Gott cooler) and the depth of the grain bed. I also suspect that each system is different so you really just need to screw around with yours to see what happens in practice. Also, and this makes a difference in the final gravity, evaporation during boiling is a function of the surface area of the liquid being boiled which is in contact with the outside enviornment. Therefore, if you use the same boiler, double the size of the batch and boil for the same amount of time, the concentration of the wort relative to the total volume of wort will be cut in half.

Anyhow, I have been brewing with my system so long that I know exactly how much my gravity will increase during a 90 minute boil. I have a mark on my mash paddle for both a 5 gallon and 10 gallon batch. I just keep collecting wort until the liquid level hits the appropriate mark on the paddle then I am usually good to go. I take a quick gravity reading with my trusty refractometer and compare that to my calculated pre-boil gravity. If I am low, I just boil longer until I reach the gravity I want before adding hops (if I am high I usually say "screw it" and go with what I have sometimes adjusting the bittering hop charge upwards). Having said all that though, I almost always brew 5 gallon batches because I am much more interested in variety than I am in volume.

[Parva]

Yep, I forgot about the double hops and double grain would double the losses but losses such as dead-space should remain as a near constant. However, as I said it's really not worth recalculating to take this into account, far easier just to double everything up.

[gunner]

Many thanks guys.

Graham.