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Mashtun Thermal Mass

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dicko

Boston Bay Brewery
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I am currently making a s/steel mash tun out of an old keg and I was wondering what Promash/ Beersmith etc figures you are using for the "Mash Tun Thermal Mass" default figure wit a similar system.

I dont expect two systems to be the same but I think that the .300 figure that Promash use as a default might be a bit low for the s/steel tun.

What are your views?

Cheers
 

big d

Hopaholic
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hi dicko
if ive read beersmith settings correctly plastic mash tun default is .300 and s/s tun default is .120
lower again :blink:

does this help?
probably not but you can compare against promash defaults.dont know if these figures alter as you put in the tun weight.

cheers
big d
 

dicko

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Hi Big D,
I was using .15 on promash for my plastic tun and it was spot on. The default of .300 was too hot and I allways had to add cold water.

I would assume that the s/steel tun would need a higher value rather than a lower one.

Yes mate, the temp of the strike water that is recommended changes a fair bit if you change this figure.

I had an assessment of Beersmith and it expired, but I notice that all of the default settings are the same between the two programms.

Someone will have a figure for a s/steel tun.

Cheers
 

dreamboat

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I am not sure how the programs calculate the temp utilising the thermal mass of the tun.... it may be assumed that the water is heated to the given strike temp, then added to the tun which reduces the temp of the water before the grain goes in, or conversely, the water is heated to the nominated temp inside the tun, so the stainless steel is also at the higher temperature, adding to the thermal mass of the strikewater.

Hard to know whether to look for a value higher or lower unless you know how it is factored in.

Dreamboat
 

Asher

Junctyard Brewing
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I'm currently using .075 for my keg mash tun.
I'm still tweakng the system but Its definately lower number than my old igloo water cooler tun (that was (`0.15).....
I'm pumping water to my tun & doing 40 litre batches BTW.....


Asher for now
 

dicko

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Hi Dreamboat,
Your first assumption is correct is that the water is heated to a temp that will equal the mash temp when it hits the mash tun and then the grain is added.

Hi Asher,
I've plugged your figure of .075 into promash and find that with a batch of 40 litres the strike temp is a lot higher than if you were batching 24 litres.
Now if you assume a 24 litre batch then the figure for the mash tun thermal mass needs to be higher to achieve the same strike temp.
This is an interesting excersise and I would be pleased to know any figures from anyone else who is using a s/steel mash tun, not pre heating it and batching approx. 24 litres.
By the way, I have mashed one brew using my current setting of .15 in the s/steel tun and the mash was too cold.

Cheers
 

jayse

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dicko said:
<snipped>
I would be pleased to know any figures from anyone else who is using a s/steel mash tun, not pre heating it and batching approx. 24 litres.
Hi Dicko,
sorry for the late reply. I've been missing in action for a few days.
Anyway iam using .300 and seems to be pretty spot on.
I don't think there is a need for pre heating also as you just use even hotter water to begin with.
I have a 1/4 inch tap in my HLT so it takes a little while to get all the water into the mash tun so i think i get even more of a temp drop than you would.
The best way to use a S/S tun i think is have a burner under it and heat the water in the tun, this is what i plan to do one day.

For a 67c mash my water will be around 80c. I then put all the mash water into the tun and measure temp which should end up around 76c then add all the grain in one hit.
Even after nearly 80 odd full mash brews iam still playing around with this constantly.

For measuring the mash temp i like to open the tun up every 15-20 mins and stir it back up again. Then i do a few measurement ie at the top in the middle and right down the bottom.
For the probe during the mash it just sits ussually just underneath the top of the grain bed. But as it is not fixed in place i can move it around to where ever and take other readings.
I have been happy with the temp reading ten minutes after dough in with the thermocouple or temp probe placed about half way down into the grain bed.

This is one thing i guess that you'll just take some basic ideas and put them into practice and fine tune to your system.
I have settled for one degree less before but like you iam after perfection and ussually would not be happy with that even though the beers always come up very well.
Most of my ales can really be mashed at anyway from 66c-68c. So generally i aim for 67c.

Hope all that helps at least a little bit.
cheers Jayse
 

dicko

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Hi Jayse,
Top info mate, I figured that the strike water would have to be hotter than what I was using for the water cooler type tun.

I am going to hunt around for some insulation to wrap my new tun with and I think that should help.

I was finding that with my water cooler tun, the strike water temp changed slightly from summer to winter and I recon that with accurate records and experience over time I will be able to make slight adjustments to the strike water being dependant on ambient temperatures that exist at the time of preparing the mash.

Part of the skill in brewing accurately is to obtain the desired mash temp with any brew, and to achieve this I plan to print up a table of strike temps in relation to ambient and grain temps and of course, batch size, to suite my system.

All the info has been a great help,

Cheers
 

sosman

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dicko said:
I was finding that with my water cooler tun, the strike water temp changed slightly from summer to winter and I recon that with accurate records and experience over time I will be able to make slight adjustments to the strike water being dependant on ambient temperatures that exist at the time of preparing the mash.
I am writing a homebrew application - not yet ready for prime time but the mash water temperature screen works (and I use it to calculate my brews).

If you are interested in a copy (free) then PM me and I am happy to send you a copy.

Its not rocket science though and a simple spreadsheet comes in handy.

brewster.png
 
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