PID sensor placement and tuning RIMs

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EccentricDyslexic

PID sensor placement and tuning RIMs

Post by EccentricDyslexic » Sat Nov 21, 2009 11:51 am

Hi chaps,

after some thought, i am thinking the best place for the sensor for my PID is sat on top of the mash away from any sparge/rims manifold flow holes. this is so the PID ensures the temp at this point is constant, because as it flows downwards it cant get any hotter and cant loose much heat in the short time before it reaches the bottom of the insulated mash tun and gets recirculated again...does this sound reasonable? the coolest place in my mash tun is gonna be the top where it is not insulated.

also, how do you guys tune your PIDs? do you do the autotune when the grain is added or when the grain has settled and is well mixed and at the required temp already? i imagine the job of the PID is primarily to keep the mash at a constant temp, not to heat it up. if one was to tune it when the mash needed heating up, then this would only suit the purpose of heating a cooler mash...? so, am i best to dough in, mix thoroughly, ensure the mash is at the ideal temp 66degrees then turn set the PID to autotune? and only use the PID to keep the mash at a constant temp?

thanks chaps!

steve

Bionicmunky

Re: PID sensor placement and tuning RIMs

Post by Bionicmunky » Sat Nov 21, 2009 7:58 pm

Hiya,

It seems the general concensus is that the best place for the PID probe is at the exit of the HERMS/RIMS Heat Exchanger/Chamber. This is because if you place it in the mash you will get over and under shoots due to lag.

On mine after 5-10mins the mash equalises with the H/E temp anyhow (I have another PID with a roving probe a la Vossy1 so I can control the HLT and/or monitor the mash temp).

Regards autotuning, I did mine on a spent mash, and the following brew it performed flawlessly. Be careful though, if you change your flow rate to much you'll need to retune.

Hope this helps.

John

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