Originally Posted by nvs-brew
1st batch i used 3L
2nd & 3rd i used 2L (to keep the wort temp down)
there has been a decrease of % with less hot/boiling water added...would u recommend using more than a Gallon?
What was your total batch size? If you did 2.5 gallons you should see about 5% abv with those cans.
if your batch is smaller the most likely your yeast isn't able to effectively consume the sugars due to a very high starting gravity.
You mentioned keeping the wort temp down so are you boiling the wort or just adding heated water? A good boil does a few things, in your case with a pre-hopped kit you are not boiling the hops to isomerize the alpha acids into bittering the beer. What you would boil for is to break down the proteins and sanitize the wort before putting into the fermenter. In your case you may wind up with a less clear brew and if not actually boiling you risk infection since the nasties are not killed off.
Have you tasted your beer yet? My bet is that since you are actually under diluting the wort concentrate your beer is under-attenuating due to the yeast getting stressed and will taste very sweet.