Ogie

Recipes 

I currently boil my ingredients in about 3 gallons of water for a 5 gallon batch. I want to start brewing 10 gallon batches but placing them in 2 separate carboys.

-Can I add all the ingredients for 2 batches in the 3 gallons I boil and then divide that into half to put into 2 different carboys and then dilute them into 5 gallon batches again?

-And if so, do I need to boil the ingredients for 2 hours now, essentially doubling the hops schedule and everything else to make up for the extra ingredients?

BeerJorge

Recipes 

There is no need to boil twice as long, however, you'll be brewing an extremely high gravity wort and your hop utilization times will tank...

BendBrewer

Recipes 

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CarPort Brewery
JCMAC Farms Garden

bonzombiekitty

Recipes 

You could double the malt and hops to make two batches, but you have to consider that with all the extra stuff in that 3 gallons, your hop utilization is going to be off. You'll probably have to boil longer, probably not an extra hour as I doubt the relationship is linear; or add more hops. Might want to check with brewing software to see what adjustments need to be made, but I've found them to give some significantly different results for the same input.

mosquitocontrol

Recipes 

If you're inside on the stove, get another pot and do two batches in parallel. That's what I do. Only adds about an hour to the brew day (because can't cool them both at the same time) but I get 10 gallons instead of 5. Helps me keep up with consumption.

fatmoose

Recipes 

There was just another thread on the board where it seems that the notion of hops utilization being tied to SG has been debunked. The author of How To Brew has backed off of that assertion as well as some other notable brewing folks. Apparently most brewing software has not caught up with this, it is a relatively new change. I'll have to see if I can find that thread.

ReverseApacheMaster

Recipes 

You can just do two boils. You will need to account for twice as much boil off though.