Preheating the mash tun

[guypettigrew]

After a decade away from AG brewing I'm very close to starting up again. All my equipment is now sorted out, the mash tun is newly insulated and everything with an electrical element in it still works!

Reading Johm Alexander's "A guide to craft brewing", amongst others, a lot is made of pre heating the mash tun with water at about 80C while bringing the mashing liquor up to temperature.

Here's what I don't understand. Why not just put liquor at 80+C into the tun and, once it's dropped to the chosen strike heat, start stirring in the grain? What am I missing, please?

Thanks.

Guy

[far9410]

hi, welcome back
pre warming the tun just saves the initial heat loss when adding the strike water, makes it easier to maintain that temp in the early part of the mash.

[kane]

Hi guy,
I tried this on my last brew, it preheated the tun great, the only downside is it took about half an hour or so to reach strike temperature (although i did use water at 90C).
I'll definitely do the same again next time, just at a lower temperature.

Kane

[guypettigrew]

Hi kane

Thanks for this.

What strike temperature were you letting it get down to?

Guy

[kane]

75C , after waiting about 20 minutes it was at 80C so i removed the mash tun lid (i was using a bottling bucket as a mash tun, wrapped with a sleeping bag and pillow covering the lid) to try and get to strike temperature a bit faster.

[bob downe]

I pre warm the tun with a kettle of boiling water to heat up the copper filter and walls of the tun. (coolbox) for 5 mins with the lid on.

I empty out the water and then add my strike water at strike temp.

Done 8 Ag's and never missed the mash temp. Just use one of the calcs around to work out the strike temp based on starting grain temp. (usually about 15C-20C for me)

For me with an average 5Kg grain bill, into a 28 L mash tun, 72-75C strike water will give me 66-68C everytime. A bit of stiring brings it down to 62C for thinner beers.

[Dennis King]

I pre heat but I also underlett so find it helps a lot.

[far9410]

dennis we spoke of this in earlier posts, do you lose less heat this way?

[Dennis King]

No I put in 2 kettles of boiling water leave it while I have breakfast and the HLT warms up, empty the water into the sink, and re-use to wash the breky plates, put the grain in straight away while the tun is still warm and start adding water. Because underletting takes longer than just pouring in I find heating the tun imperative.

[far9410]

what advantages with underletting then, perhaps no dough balls eh?

[boingy]

Why not just put liquor at 80+C into the tun and, once it's dropped to the chosen strike heat, start stirring in the grain? What am I missing, please?

That is exactly what I do and you are not missing anything. The only problem is choosing the right temperature.
Too low and it will not pre-heat the MT enough. Too high and you face a delay whilst it cools a bit (but you can leave the lid off to speed it up).

As it turns out, 80C is perfect for me and I also sparge at that temp so my HLT is permanently fixed at 80C.

[Dennis King]

Yes less dry clumps, buy the time you reach the desired water level just needs a quick stir, I also tend to pour off a few pints and recirculate to get an even temperature, check temperature, job done. I believe most commercial brewers underlett.

[Kev888]

I too just use hotter liquor to allow for cooling in heating the cold mash tun, by which time it has reached strike temperature (assuming i got it right anyway). This wouldn't work with underletting though because the grain would meet the liquor before it had time to lose heat to the mash tun, and in my case thats hot enough to stop the enzymes.

Cheers
kev

[Hogarth]

I add the mash water at 85°C. There's usually plenty to do while it's coming down to strike temp. If you get impatient you can always splash it about with the mash spoon, which cools it down more quickly. (At least, I think it does.)

[mooj]

I don't pre-heat with additional water either. The quickest way I've found of cooling after overshooting the strike temperature is to pour out some of the mash liquer into a large jug, let it cool for a minute or so, then add back to the tun (repeat as necessary). I'm always surprised how quickly this works.