A bit of maths: Reduction in temperature by addition of grain to hot water for mash

[jezbrews]

Tried searching the site, maybe I didn't search well, in fact Google didn't seem to understand either...

When you add grain to the heated water to become mash, say 5kg of grain at 20°C to 20L (for the sake of ease as 5 is exactly ¼ of the heated volume) of water at 65°C, what temperature would you expect the hot water to drop to? It's clearly not simply a case of averaging the temperatures of the masses (ie 25kg) since they're different masses with different heat conductivity.

 

[Rwilts]

Theres a tool available here to work it out.

https://www.brewersfriend.com/mash/
I normally just set strike water temp at 70 and mash in.

 

[gyurmaember]

If you do your dough in slowly as you should it's negligible. As your kettle should catch up very quickly.
It mostly a problem for US brewers, with crappy electricity, or maybe if you do huge batches.

 

[jezbrews]

Theres a tool available here to work it out.

https://www.brewersfriend.com/mash/
I normally just set strike water temp at 70 and mash in.

Bookmarked! Thank you! These people think of everything!

 

[jezbrews]

If you do your dough in slowly as you should it's negligible. As your kettle should catch up very quickly.

It wasn't really a fair assessment I guess, I was trying to add luke warm water to replicate as I'm doing a dummy run on the Brewzilla... but if course that's really about mass and doesn't replicate the effect suitably. But at least I know in advance! Beautiful.

 

[Buffers brewery]

https://jansson.us/MashPhysics.html#:~:text=Subscript w is for strike,the specific heat of water.
Some bedtime reading

 

[The Baron]

I do not worry if using a AIO for mash temps as I too find my machine catches up very quickly but if brewing oldy styley you do need a higher strike temp to compensate for the grain temp being lower

 

[hoppyscotty]

I've often wondered how this impacts enzymes. On the basis that if you raise the temp then enzymes that are active at lower temps are essentially 'killed off' or de-natured (not sure what the correct word is) then if you dough in wit the water a good 8 or so degrees hotter than your target mash temp then wont those first grains you pour into the hotter water be denatured until such time that sufficient grain has been incorporated to bring the temperature down?

Typically I only mash in a few degrees hotter than strike temp and bring the system upto temp once mashed in to avoid over heating the first portion of the grain. Am I over thinking this?

I do struggle to hit FG sometime and often finish a good 2 to 4 points higher than target despite hitting overall OG on the nose and wonder if my average mash temp over the hour long mash is higher than target mash temp thus producing more alpha analyse than beta analyse.

 

[Buffers brewery]

If you’re over thinking it @hoppyscotty then so am I (nothing new there ). I used to heat my strike water +5C to mash temperature but now heat my strike water to mash temperature then use my HERMS to bring the temperature back up after adding the grain. Takes about 20-30 minutes for a 5kg grain bill.

 

[hoppyscotty]

Glad I'm not the only one Buffers. On the brewzilla it brings the temp up in a few mins once mashed in and on my recently built up 3v RIMS system only takes around 10 mins or so, therefore no big deal on brew day but would be nice to mash in and be at mash temp on the nose and maybe save a bit of leccy.

 

[The Baron]

I set my mash temp and add my grain to that temp as I am adding it the temp may drop a couple of degrees but the AIO kicks in and is heating it back up to mash temp as I am mashing in -only takes a few minutes or so
Ps I do let my grain get to room temp before adding to minimise the difference usually weighed out the night before