planning my first BIAB

[turketron]

After having done a couple extract batches I'm hoping to do my first stovetop BIAB tomorrow afternoon. I bought a NB 5gallon Cream Ale kit and plan to split it in half and make two separate batches BIAB-style. I'm trying to calculate the best way to manage a 2.5gal batch on my stovetop with only a 4-gallon pot available to me. The various online calculators show that to mash with the full boil volume I'd need 4 gallons of strike water, which my pot wouldn't be able to hold in addition to 4lbs of grain.

My plan is to mash with less water and then top off either pre-or post boil? I realize full boil volumes are ideal but I don't have the equipment for it.

My tentative plan is to mash the 4lbs grain in 1.5 gallons of water(1.5 quart/lb ratio, which I gather is pretty normal), allowing for 0.5 gallons of water absorption by the grain. I'll then top off the remaining ~1 gallon of wort with another 1.5 gallons to reach a pre-boil volume of 3.5 gallons, and then boil for 1hr, allowing for 1 gal/hr boil-off. This should leave me with 2.5 gallons going into the fermentor.

Does this make sense or is there something I'm not taking into account?

 

[Euphist]

If you have a second pot big enough, I would heat your top-off to about 170 and dunk sparge your bag in that before adding it to the mash.

 

[wilserbrewer]

My tentative plan is to mash the 4lbs grain in 1.5 gallons of water(1.5 quart/lb ratio, which I gather is pretty normal), allowing for 0.5 gallons of water absorption by the grain. I'll then top off the remaining ~1 gallon of wort with another 1.5 gallons to reach a pre-boil volume of 3.5 gallons, and then boil for 1hr, allowing for 1 gal/hr boil-off. This should leave me with 2.5 gallons going into the fermentor.

Does this make sense or is there something I'm not taking into account?

Your efficiency will suffer greatly if you do not rinse the grain more. Perhaps mash in w/ more water or all the water if it fits. Or say mash in w/ 2 gallons, then dunk sparge in a bucket or another pot w/ another 2 gallons which should yield 3 1/2 gallons, then boil down. Basicly the more you top up, the less water available to rinse the grain. At the very least pour the additional water through the grain bag.

I would mash in w/ 3 gal and add the grain bag, then top the pot nearly full and bring up to mash temp and rest. Then pull the bag and you will have 3.5 gal.

Topping up w/ fresh water kills efficiency and should be avoided if at all possible.

 

[kwingert]

I mash using 1.5 quarts water to 1lb grain and then rinse the grain with extra water I've heated to get up to my preboil volume. It seems to work.

Are you really boiling off 1 gallon of water? That seems like a lot. I also use a 4 gallon pot and I only boil off less then .5 gallon which is about 15% evaporation rate.

 

[turketron]

Thanks for the replies!

I would mash in w/ 3 gal and add the grain bag, then top the pot nearly full and bring up to mash temp and rest. Then pull the bag and you will have 3.5 gal.

This makes sense, I'll give it a go and we'll see what happens.

My next step is to get a propane burner and a bigger kettle as soon as possible, but I'm too impatient in the meantime and I want to brew today.

 

[Antler]

I brewed a 5 gallon batch in a 7.5 gallon pot in the same way you did. Not sure how my effiency went but the process went smoothly

 

[turketron]

So it's all done and in the fermentor, and I think it went fairly well. I mashed in a little hot, my thermometer was reading at just under 160 for the first 5 minutes or so, but I left the pot uncovered for about the first ten minutes, and then covered it for the rest of the hour, the temp dropped to 148 so I gave it a little flame and ended the hour at about 152. I gave the grain sack a good squeeze as I pulled them out, and I poured about 1/2 a gallon of (heated) water over the grains to reach my pre-boil volume of 3.5 gallons.

In response to kringert's post, I think my calculated boil-off rate was a bit high (even with a pretty vigorous boil) as I ended up with more than 2.75 gallons going into the fermentor instead of the 2.5 I was shooting for. But, my efficiency was higher than I had expected, because I nailed my target gravity (1.040) going into the fermentor.

Next up I'm going to do some calibrating to dial in my boil-off so I can nail my water volumes for when I brew the second half of the kit.