I have no argument with what you say, and I made no comment on the BIAB time savings.
I thought you did. If not, then I'm not sure what you meant by "
but it does make a big difference in time." And the way I read this next quote makes me think you
do have an argument with what I say.
Making a 2.5 gallon batch vs a 5 gallon batch has time savings whatever you brew on. Whatever equipment you have it is always quicker to sort out and crush grain for a smaller batch. It is always quicker to bring a smaller batch to the boil and cool it.
Sorry but either I'm missing your point or you aren't paying attention to mine because I think you're wrong. If your heat source was a fixed factor then yes, volume would affect boil time all the way to the point where too much water and you can't get a boil.
But heat source is not a fixed factor. We all have different burners and different stove tops and different heat sources. In most cases this is even more dramatic when you compare the 5g brewer to the 2 or 3g brewer. When brewing small amounts most are inside using a stove top and that is a big difference between those using brewing burners.
You would be correct if most 2-3g brewers were using the same equipment as the 5g brewers. It would be faster to boil 3g on a Blichman burner than 7g. But I suspect most trying to boil 3g are not using something like a Blichman burner. Instead I'd bet a nickel the time to reach boil is very similar on average when you compare a 5g brewer to a 2.5g brewer.
And the same goes for chilling. If you were correct when you say "
whatever equipment you have" then why are there so many different chilling options out there? Why are there happy users boasting how they save so much time and water because of the new XYZ chilling product they just bought? Equipment
does matter - it is a major factor. You'd be correct if the 5g and 2.5g brewer both used the same pump and the same plate chiller but that is rare and a minor time savings.
It is always quicker to drain the bag in a smaller batch. I've just seen a lot of posts by Owly055 where he has said (or even boasted) how quick he can do a batch, but doesn't say that he normally does 2.5 gallon batches; I think it gives a false impression, as I think everyone (regardless of equipment or method) will be able to produce a smaller batch quicker.
Again I would disagree. Well, maybe a smaller bag drains faster, I'm not so sure about the physics there. Seems like a sponge with the same absorption will drip at the same rate no matter the size. Squeezing will take longer due to size. Either way I can't see it being a major factor. The obvious time savings for BIAB is once the bag is hoisted you can start the boil right away during that drip time and that is a time savings over even a batch sparge.
With a 30 minute boil (which I think he said he did), I think I could easily do a 1 gallon BIAB in under 2 hours - size does count when you are telling people how quick you can do something.
The 30 minute boil is I see more people doing but that isn't a factor of size either. That is people saying conversion is over and they don't need the full 60. Batch size isn't related to that.
Again, size isn't the main factor in nearly every time saving biab story you read. As I said before the main factors are clean up (1v instead of 3v) and sparge. I
will agree that most biab brewers leave the details out on sparging.
Look at it this way. Most batch spargers can boast time savings over when they used to fly sparge for 45+ minutes. Most biab brewers (depending on mash and sparge method) can boast time savings over the batch spargers. This is true no matter the batch size.
There are some time savings with smaller batches but mainly those are minor. If you deal with the same flow rate then yes 2.5g will drain faster than 5g but that isn't where the main time savings are coming from. And sure you could take your 5g batch burner and plate chiller and save time heating and cooling, but imho that isn't the main point and it seems wrong to assume you'd use the same equipment on different batch sizes.
Shrug. Cheers.