Brewing efficeny question when going from 5 to 10 gallon batch

[rwing7486]

This weekend I am looking to brew my standard American wheat recipe, but instead of brewing 5 gallons I am looking to brew 10 gallons as I plan to fill two fermenters with one being my normal American wheat recipe and the other fermenter I plan to rack to a secondary over raspberry puree.

My question is when I'm brewing a 5 gallon batch of this beer my brew house efficiency is at 78%, but now I am mashing twice as many grains in my tun will this affect my efficiency or will it stay the same? I want to think my efficiency will stay the same as according to beersmith if I mash 20lbs of grain at 1.25 thickness I will have 9 gallons of sparge water which means I should get a really good rinse of the grain when batch sparging in two steps - 4.5 gallons at a time

 

[pricelessbrewing]

As long as the process, mash thickness, and total water to grain ratio doesn't change then the efficiency shouldn't change.

 

[Brewenstein]

Do you normally do two sparges? I do one for a 5 gallon batch, but two for a 10 gallon batch due to volume restrictions in my mash tun. I get about 4-5 % jump in efficiency from the extra sparge. Maybe adjust your efficiency to 80% to split the potential difference.