ok... so now i am trying to understand how to calculate my batch sparge and am finding it a bit confusing, specially because most of the articles and texts are not in metrics... so lets see if I got it right...
lets say i am doing a 20 L batch... my boil size has to be 24L, acording to my equipment...
so I mash with a 3 liters per kilo thickness... so say a 4kg grain recipe... considering 1 liter absorbtion per kilo of grain...
So 4 kg of grains...
12 liters to mash...
consider 1,5 liters of dead space...
that would give me a 6,5 litres to the boil kettle... so before I vorlauf that first running I would add 5,5 liters of sparge... the after vorlauf i'd run off 12 liters...
then for my batch sparge I would add 12 liters, mix it all, vorlauf and run off to the boil kettle...
a bit confusing but can anyone correct me if i am wrong... please...
cheers

The easiest way is to measure your first runnings. Subtract that amount you need to have at boil, and you have your sparge water. Since the grain won't absorb any more water, the amount of water you use for sparging is going to come out as your lite wort.

so say I ran off 6,5 litres... to complete my boil size of 24L I'd be missing 17,5 liters... so I could divide that by 2, which gives me 2 batch sparges of 8,75 liters?
right?

so say I ran off 6,5 litres... to complete my boil size of 24L I'd be missing 17,5 liters... so I could divide that by 2, which gives me 2 batch sparges of 8,75 liters?
right?

Yup that is right. My mash paddle I marked by putting in measured amounts of water and then filing a line on it. So after the first running I would stick the mash paddle in the boil pot and know how much I had to add to get my boil volume.

yep... I am gonna do something just like that for my mash and boil tun that are the same size... I did it for my fermentation buckets and is really usefull...