BIAB Query - initial volume

[klaus]

I am slowly putting together my kit for BIAB and have been looking at a number of recipes in Graham Wheeler's book. The one thing I am still unsure about: generally the initial volume is somewhere around 31 to 33 litre for a 23 litre batch.

So I would heat up 33 litre and the difference to final batch size is caused first by mashing/soaking the grains due to water retention and then by boiling for 60/90 minutes.

This makes sense but my question a) is it as simple as this (I guess it probably is) and b) is there some way of estimating the difference? I don't use any brewing software yet ....

 

[BeerEagle]

It nearly is. There will be some variation depending on the surface area of your boiler (wider will lose more in the boil , I think). Test boil with some water so that you know how your kit performs

Also there's some to be lost if there's any dead space (ie. liquid left behind) in a vessel at any stage in your process. Less of a problem for you as you're BIABing in a single vessel.

Anyway, whatever happens, if you lose more than you'd planned, you can always top up in your fermenter.

Just run your system a few times. Keep copious notes and adjust until you get it spot on every time.