1 gallon batch question.

[tbel]

I've been planning a couple of one gallon batches using the BIAB method.
As part of my planning I boiled 1gallon of water for 30 minutes to help me figure my loss to evaporation(and cooling). After cooling what was left to 72 degrees I measured the amount and got 64.8 oz. So I'm losing 63.2 oz in 30 min. To me that seems like alot. I plan on sparging by dunking the bag of grains in a second pan of water raised to 170(or maybe just a little higher). So I figure for my total boil volume I'll need 1.99 gallons. This seems like alot, will this effect the way my hops are utilized? It's going to be a Sweet Stout. Don't know if anyone has any tips but just in case I'll give the recipe I'm using. I would like this to fall within the BJCP guidlines for a stout but depending on the Recipe software I put this in some say doesn't fit especially the bitterness and others say it does. Just going to add less lactose to the second batch to see how it comes out.
So here it is...
1.99gal boil volume
1 lb English Maris Otter
1.6oz Belgian debittered Black malt
1.6oz English Chocolate Malt.

Mash @ 152F for 60 min. Sparge/mashout @ 170 for 10min.

60 min boil with 3.2oz of Lactose and 0.25 oz of Willimette (AA-4.7%) for the entire boil.

Thanks in advance for any help.

EDIT forgot to add I'll be using Danstar Nottingham yeast. I was thinking I'd just split a pack between the two batches.

 

[pvtschultz]

I seem to boil off one gallon whether I am making a 2 gallon or 5 gallon batch of beer. I shoot for the same boil rate (look) with each batch and that has served me well so far with this new propane burner.

 

[tbel]

I wouldn't expect it to change with volume. I just thought 1 gallon an o hour seemed like alot. I can't say I've paid much attention previously because I've don either Partial mash or extract kits from NB and just followed the Instructions.

 

[C-Rider]

I do 1.75 gallon batches BIAB and I loose between .5 - .75 gallons to the boil. Depends on how much gas I give the burner, how "rolling" the boil is.