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keeping mash tun temperature at constant 65 degrees celcius


Grandmaster Brewer
Dec 15, 2011
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i am having trouble keeping a constant temperature in my mash tun for 45 mins. i need to keep it at a constant 65 but it falls quite alot. i do not want to insuate it. i wondered if there was a device that i could out in that will heat it up if it falls below this temp.
Hi, sorry its a 240 litre stainless steel mash tun. Single layer with very thin insulation around it.

There are temperature controlled electric heating elements you could use.  That is a very big container for a 75 liter batch.  massive amounts of heat are lost in the head space.  Submersible heating elements would probably scorch the wort though.

You could also pump the wort through a coil in a 65C water bath and back into the mash tun.
Well we only did a 75 litre batch for testing. Would a full batch be better then?
There will be more heat mass and which will cool slower.  Generally speaking, it should stick closer to the target but you will need to adjust it for the equipment as you learn what it does.  I have brewed with a pro on a 3 and 7 barrel system that seems to stick close to the target. 

Pro brewers are shooting for maximum efficiency due to keeping costs as low as possible.  You will want your efficiency over 80% and closer to 90% or you are pouring money out to the cows and horses.  that may mean heating your wort to keep it ina conversion range.  Time will tell.

Hi, sorry its a 240 litre stainless steel mash tun. Single layer with very thin insulation around it.

Good God Man, You brewing for the entire town. You can get better heat control with a 50 to 64 qt (47 - 60 L) ice cooler. 240L is a lot to keep constant.
I would try (taking into account that you are not using an external heat source on your mash tun) household insulation, wrap that with metal tape (the type used in A/C duct work). 
Wow .... 240 L is huge ... Anyway for my little 15 gallon mash tun I circulate the wort through a copper coil immersed in a 3 gallon thermos. I maintain the temperature in the thermos with a heatstick and temp sensor.