How much water?

[Wekslap]

How much water do I need in my 32 litre peco electrim digital boiler masher to end up with 23 litres using BIAB please?

[Secla]

Depends on alot of things. recipe/equipment etc.
I just did a 5% ish ale, Full volume so didnt sparge. About 5kg of grain + about 3 litres of boil off/dead space etc.
Total volume was around 33l of water

[Wekslap]

My first recipe is 3.5kg maris otter and 350gr of light crystal malt if any help.

[Secla]

assuming your doing full volume biab

allow 1l absorption per 1kg of grain
5% boil off per 30 mins of boil,
+ whatever the dead space is in your equipment

[rpt]

Get the BIABacus spreadsheet from biabrewer.info. It will do all these calculations for you.

[Fil]

dead space you can work out in advance with a simple drain test, you can expect to loose about 1-1.5l of liquid per kilo of grain to absorption depending on how much you drain/squeeze/wring out.. and between 1/2 to 1 litre to hop absorption and trub, your boil off rate however depends on your equipment and brewspot conditions, so will take a few brews to sus out, so start with an estimation between 7-15% (lower end imho if using a single element circa 2kw)

my advice would be to focus of attaining the gravity in the desired ball park foremost, a few pints extra or less isnt really going to matter, but you can always boil longer to reduce more ( may increase hop bittering marginally) or 'liquor back' (add water to) the finished brew to fine tune the volume if you wish,,,

[Bazz]

I have a similar boiler to you and for most of brews (Normal strength 4-5.5%ABV) i always start with 27 litres in the boiler and mash in this, after the mash is complete i sparge the grains once removed with a further 7 litres of water that i have heated in a separate pan on the stove. I always hit my desired quantity in the fv. You could also just liquor back post boilto hit your target gravity, but i find i get increased efficiency sparging.