Building a low-cost BIAB system

[Kunal Vanjare]

Hello guys, amateur homebrewer here, but with a background of manufacturing technology (not from food industry though).

I was wondering if there was anybody here who has built a BIAB system (Brew in a Bag/Basket ... preferably basket) system here from scratch and would like to give me a few pointers.

I have some queries :-
1. I am aware fermentation would not be a part of this system, but if it HAS to, how would you manage that?
2. Is provision for Whirlpool a MUST for such a build? Or can homebrewers make do with a paddle?
3. I am planning to go for SS tube heaters with a Digital Temperature Controller to control the mash & boil temperatures. A PT100 thermocouple would sense the temperature inside the vessel. Any suggestions on this?
4. Would I need a Digital Timer? To control timings i.e to switch off the system automatically upon completion of mash & boil..
5. Minimum thickness of SS sheet metal for making the vessel?
6. SS304 / SS316 as the material of construction?
7. What about the finishing of the vessel from inside and fittings, connections etc.? Any particular guidelines I need to follow?

Any help will be appreciated. Apologies if this has been asked before, as I did do a quick search that did not lead me anywhere

Thanks.

 

[ChiknNutz]

Just a couple of thoughts from a relative newbie in BIAB.

• This all can be as simple or as complicated as you like. For me, I am keeping this all as simple as possible. I recently moved to BIAB from extract to up my game. The only equipment change I have made is the BIAB bag itself. Meaning, I still brew using propane using the same 10G kettle.
• While I suppose you can ferment in this vessel, the downside is it ties up your whole system for that duration. I'd venture to say most like to have dedicated vessels for each part of the process so they can have multiple batches at various stages of completion. For me, I have a brew kettle, fermenter and kegs...all SS. While I still have plastic buckets I used for fermentation, I like SS for durability and might add a second one at some point. I only have 2 corny kegs and will likely add a couple more sooner than later.
• I whirlpool old-school with a big plastic spoon. It would be nice to have a proper whirlpool setup, but so far it's fine as-is for me.
• I have no temp control aside from me keeping watch on it with an electronic thermometer.
• While no-weld fittings are acceptable, I think most agree that properly welded fittings are superior as you are sure they won't leak and also won't hide bacteria if dressed properly post-welding.

 

[Kunal Vanjare]

While I suppose you can ferment in this vessel, the downside is it ties up your whole system for that duration. I'd venture to say most like to have dedicated vessels for each part of the process so they can have multiple batches at various stages of completion. For me, I have a brew kettle, fermenter and kegs...all SS. While I still have plastic buckets I used for fermentation, I like SS for durability and might add a second one at some point. I only have 2 corny kegs and will likely add a couple more sooner than later.

Valid point. And quite obvious. How did I not think of this?!

I whirlpool old-school with a big plastic spoon. It would be nice to have a proper whirlpool setup, but so far it's fine as-is for me.

Yeah a big spoon/paddle is what I use too. But I saw videos of people introducing a whirlpool with the help of a small pump and fittings where they recirculate the beer which causes the whirlpool. I guess I need to design and then check the costing to see if it is feasible.

I have no temp control aside from me keeping watch on it with an electronic thermometer.

Well I need somebody to tell me if automating the temperature control process really is worth it.

While no-weld fittings are acceptable, I think most agree that properly welded fittings are superior as you are sure they won't leak and also won't hide bacteria if dressed properly post-welding.

Welded fittings are definitely more reliable. What I wanted to know was that are welded fittings treated with some chemical to make them brew-friendly? I don't want them to shed particles or possibly react with the beer, if that is even a problem with Stainless Steel. (I doubt it.. but want to be doubly sure).

 

[Gruel]

Just some random remarks:
1) I wouldn't go overboard with pumps etc. initially.
2) Ditto for control automation. Having more than one thermometer for monitoring (or one that you really trust) is good though.
3) it's much easier to get a few kW power out of a gas burner/range than out of a 120V electric circuit.
4) stainless steel: I don't think 304 or 316 matters, but you want the low carbon L version (304L or 316L) if you use a gas burner, to prevent heat sensitization and eventual corrosion at the spots where the flame hits the steel. Ideally your kettle would have a composite bottom (aluminum or copper sheet sandwiched between stainless steel) for use on a gas burner. For an electric immersion heater or an inductive cook top it doesn't matter, I think.
5) thickness: I have one stainless 5 gallon kettle that actually developed a one inch crack from the top edge. Apparently 0.5mm is too thin if combined with a rolled edge.
6) welding: probably a good idea to passivate anything welded or machined.

 

[Kunal Vanjare]

Just some random remarks:
1) I wouldn't go overboard with pumps etc. initially.
2) Ditto for control automation. Having more than one thermometer for monitoring (or one that you really trust) is good though.
3) it's much easier to get a few kW power out of a gas burner/range than out of a 120V electric circuit.
4) stainless steel: I don't think 304 or 316 matters, but you want the low carbon L version (304L or 316L) if you use a gas burner, to prevent heat sensitization and eventual corrosion at the spots where the flame hits the steel. Ideally your kettle would have a composite bottom (aluminum or copper sheet sandwiched between stainless steel) for use on a gas burner. For an electric immersion heater or an inductive cook top it doesn't matter, I think.
5) thickness: I have one stainless 5 gallon kettle that actually developed a one inch crack from the top edge. Apparently 0.5mm is too thin if combined with a rolled edge.
6) welding: probably a good idea to passivate anything welded or machined.

1. Got it. I'll keep pump for whirlpool as an optional upgrade.
2. I'll give this some thought. Still leaning towards having a temperature controller & timer. Won't add too much cost, maybe this can be kept as optional too.
3. People here usually homebrew on their gas stoves. Very few actually use a gas/propane burner. Maybe I can slightly oversize the heating element thereby reducing the heating time.
4. Alright. SS304L it is. 316L is costly.
5. I will go for 18gauge (1.2mm) thick sheet.
6. How do you passivate a welded joint? Any specific chemical you can suggest?

 

[ChiknNutz]

What is the capacity of the system you are planning? Probably the most common size here aims at ~5G batches.

 

[Kunal Vanjare]

What is the capacity of the system you are planning? Probably the most common size here aims at ~5G batches.

I actually had smaller 10Litre batches in mind to begin with. Mostly because I usually brew 1G or max 1.5G batches. Will go for 5G batches after that if I feel like.

 

[Gruel]

Regarding passivation: there have been several recent discussions of this topic on this forum.
I think in the end most agreed that a warm 5% citric acid solution is the best way to remove excess surface iron (and corrosion) and prepare the chromium rich surface that can then build up the passive chromium oxide layer by exposure to air.

Lemon juice has the right concentration and works for passivating small parts or vessels, but is too expensive if you want to fill a reasonably sized brewing vessel.

For details you should look up these recent threads directly.

 

[Kunal Vanjare]

Regarding passivation: there have been several recent discussions of this topic on this forum.
I think in the end most agreed that a warm 5% citric acid solution is the best way to remove excess surface iron (and corrosion) and prepare the chromium rich surface that can then build up the passive chromium oxide layer by exposure to air.

Lemon juice has the right concentration and works for passivating small parts or vessels, but is too expensive if you want to fill a reasonably sized brewing vessel.

For details you should look up these recent threads directly.

Will do. Thank you so much.