GF - Starting boil as I sparge?

[Cobnut]

My sparge water heater is a cheap 30L tea urn I bought when I was doing BIAB.

I modified it with a proper tap, but if it's only for sparge water, I don't think I'd bother if I were to do it again; and insulated with a £5 foil-backed camping mat from Tesco (Other supermarkets available).

Photo is from a few years ago in pre-GF days and probably shows it approaching boil.

It has a theremostat in degrees C and is not far out at 75C which is what I usually sparge at.

[Kev888]

I have a GF and a sparge water heater.
so..
I mash, then I lift the basket and start to sparge from the sparge heater.

Question... can I start the boil timer immediately? or do I have to wait till all the sparge water has gone through the grain?

I only ask as it takes an age to sparge (roughly 20 mins) and if it makes no difference I could be using this time to start the boil.

Continuous sparges in 3+ vessel systems can take much longer than that, so for decades homebrewers have been turning on the boil kettle as soon as there is sufficient wort in it. There is no reason to wait, and raising the temperature sufficiently to denature the enzymes stops the sugar profile in the collected wort continuing to change whilst waiting for the sparge to finish, so it can even be slightly beneficial for consistency.

The only real difference with the GrainFather is the grain basket partially blocking the kettle's opening, so setting to just below boiling until that is removed is probably prudent - just to avoid boil overs.

There is a theoretical possibility of steam from the nearly-boiling wort overheating the bottom of the suspended grain. But at least in my tests this hasn't happened in practice, the sparge liquor running through (and the thermal mass of the wet grain) prevents it gaining too much temperature. So all seems fine to me.

[lord.president]

I’ve always done this- does it not say in the instructions to do this?