Mash Temp Probes

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Womball

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Gday,

I've got a three SS pot 70L system. I installed two MashMaster dial thermometers on my mash tun as I brew single/double batches. The first thermometer I installed above the ball value is to high for a single batch to give a good reading.....it's lucky to sit just in the mash itself. So, I went out a brought another and installed it on the side approximately in the middle of the level of a single batch.

Question is, on a double batch run the top always reads higher than the bottom. The usual story of my mash-in/mash-out and sparge is this (single infusion/batch sparge)...


Mash-in: Top reads around 1 degree higher than the bottom
Raise to mash out: Top seems to read correctly @ 76 degrees, bottom barely climbs above 72
Drain mash tun and sparge: Top raises to around 78 degrees, bottom might get to 74.

I thoroughly mix the grain bed after adding water for mash-out/sparge and I've also calibrated the thermometers (I have 4 and circulated both mash tun temp probes but I seem to get the same result.

I realise that the top might be higher than the bottom due to heat rising.....and all that thermal dynamics stuff, but I wouldn't expect up to a 4 degree difference.

Bottom probe sits around 60mm from the bottom of the mash tun, top sits around 120mm from the bottom. Both have 60mm probes.

Cheers,

Womball.
 

spog

The Odd Drop Brewery
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Womball said:
Gday,

I've got a three SS pot 70L system. I installed two MashMaster dial thermometers on my mash tun as I brew single/double batches. The first thermometer I installed above the ball value is to high for a single batch to give a good reading.....it's lucky to sit just in the mash itself. So, I went out a brought another and installed it on the side approximately in the middle of the level of a single batch.

Question is, on a double batch run the top always reads higher than the bottom. The usual story of my mash-in/mash-out and sparge is this (single infusion/batch sparge)...


Mash-in: Top reads around 1 degree higher than the bottom
Raise to mash out: Top seems to read correctly @ 76 degrees, bottom barely climbs above 72
Drain mash tun and sparge: Top raises to around 78 degrees, bottom might get to 74.

I thoroughly mix the grain bed after adding water for mash-out/sparge and I've also calibrated the thermometers (I have 4 and circulated both mash tun temp probes but I seem to get the same result.

I realise that the top might be higher than the bottom due to heat rising.....and all that thermal dynamics stuff, but I wouldn't expect up to a 4 degree

Bottom probe sits around 60mm from the bottom of the mash tun, top sits around 120mm from the bottom. Both have 60mm probes.

Cheers,

Womball.
must be a problem with keeping the mash agitation and keeping the heat evenly distributed ,as you say 4 temp probes all calibrated but a same reading from all 4 in the same possie ,perhaps the grain bed is trapping cold pockets and giving these readings.is you heating gas or electric?. If gas then it has to be agitation (IMO). If electric could the probe be too close to an element thus giving a false reading becaus of the agitation issue (my claim). My 2 bobs worth,happy to be corrected. ..cheers..spog...
 

Womball

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Cheers Spog. After writing this I re-calibrated and rotated the probes this morning before hosting a single batch brew for a mate of mine brewing on my system. Seemed to get a good reading on the bottom temp probe this time (BTW, my mash tun isn't heated, only the HLT and Kettle are with propane)

I'll brew a double again next weekend and see if the numbers add up.......
 

verysupple

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I like that you're really thinking about what's going on. But it seems like you're pretty experienced so does it really matter what the actual temp is? By now you should be able to determine if the mash temp was right based on taste (I understand the thermometers may be new but you can get a feel for if the body of the beer is right after the first brew if it's an old recipe).

I gave up on super accurate mash temps ages ago because it never mattered how much I mixed, the temp was up to a degree different if I moved the probe. Now I just probe in 3 or 4 locations and if my mental arithmetic tells me they're about right on average, then bingo.
 

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