Use a lauter tun for BIAB?

I am thinking I am going to make the jump to all grain very shortly. I would like to do BIAB first. With that being said, I only have a 32 quart kettle, and I've been reading this isn't sufficient enough, due to the lack of space for sufficient water volume and the grain bill for a 5 gallon batch. So I was wondering, can I bring the water up to temp for the mash in my kettle, then use a lauter tun or just an igloo cooler for that matter for the mash, then transfer back to my kettle and do the boil from there?? Obviously keeping the tempurature might be more tricky. I have done some searching around, and I can't find where this method is addressed, if at all. Has anyone tried this or do you have any suggestions? I might just pick up a bigger pot to eliminate this issue anyways, just thought I might put this out there.

Yes. It can be done.

https://www.homebrewtalk.com/f36/thought-my-first-biab-all-grain-384699/

Awesome. Thank you!

Dunno if you are interested, or not, but it's not unheard of to just go a little lower volume on mash and top up to the correct volume before you start your boil.

If you know the boil off rate for your kettle, the volume of wort in your kettle after mashing and your pre-boil requirement you can do either of a couple of things.

Squeeze as much as possible out of the bag after doing a dunk sparge, two or three times, then add the required volume of water to get to your pre-boil volume, or, use a separate vessel with the exact volume of sparge water needed, don't need to worry about squeezing everything possible from your bag after the mash in this case, and add the sparged wort to your total in the kettle.

Personally, I find doing a few dunk sparges in the kettle and squeezing the bag until practically nothing else will come out seems to work quite well. Got good efficiency too the couple of times I've done it

A 32 qt should be sufficient for most BAIB 5 gal batches. In order to maximize the smaller kettle, fill close to the rim AFTER adding the grain and most of the strike water. Trying to add the grain to a mash that mistakenly is 32 1/2 quarts in a 32 pot is a MESS! reserve a few quarts and top up, even at the end of the mash...also look int performing a dunk sparge in another pot of bucket, or simply slowly pouring the last gallon threw the grain bag will work as well as it is held above the kettle in colander.

I'm sorry to hear that a 32 qt pot isn't big enough to BIAB in because I've been using a 30 qt for the past 2 years. I have done no sparge with that but the mash is pretty close to the top (for a 1.057 OG batch) but by using a little less water and then a dunk or pour through sparge it works out well. You do have to keep the boil under control so you can start with a smaller amount of water than many suggest but it can easily be managed and if you do boil off you can top up at any time in the boil.

Your first choice is still an option. For a couple years, until I finally built a MLT, I used a cooler to mash and then would scoop the wort into a plastic bucket lauter tun. It was messy but worked.

However, I see the 32 qt as less of a problem for the mash, since you never go above 170F so there are no boil overs. You may just have to use less water in your mash. The biggest problem I see is doing a full boil for a 5 gallon batch. With my burner setup, I start with 7 to 8 gallons for a boil down to 5.5. Since your kettle is 8 gallons you wouldn't be able to do this. You could boil and top off, as has been suggested.

I start with 6 1/2 gallons and boil down to 5 1/2. All it takes is decent control of the heat you add. You want a rolling boil, not a jumping boil.

My kettle is about 13 to 14 inch in diameter. I feel in the past I have lost about a gallon or so during other boils. I was going to double check the BIAB calculator to remind myself of what my pre-boil volume should be. I believe it was 7.25 gallons or so. Ill try the dunk sparge method before I go and buy the igloo cooler. Would like to try and use what I have first. I watch my boils like a hawk, so I will be sure to keep a rolling boil. Ill probably do the dunk sparge in a seperate bucket with the full amount of sparge water. Ill see how it goes when I get a brew day next month! Trying to learn as much as I can before attempting my first all grain batch!

Cluckk, just so I am sure I understand, when the boil is done and I transfer to the carboy and I have lost a little more water than expected, can I still top it off with some clean water like in extract and partial mash brews, or if I do happen to boil over, do I just top it off again in the kettle at any point during the boil?

Edit: I was wrong about the pre-boil. Should be around 6.5 gallons like what was already said!

I do almost exactly what you're planning. I heat my strike water in the kettle and use my Igloo cooler as a mash tun, but use a BIAB bag instead of a false bottom. Works well. Only issue is that if I'm doing a small batch with less than about 7 lbs of grain, the mash temperature drops a little. I'll lose maybe 3F in an hour. With 5 gallon batches and >7lbs of grain the temperature holds well.

I will be doing some experimenting to see what method I like best. I like the idea of the cooler because the temperature control seems easier. If I don't like only using my kettle and a seperate vessel for a dunk sparge, I may go with the mash tun idea.