Johnson a419

[instinct2]

?... I have an extra Johnson A419 unit laying around. I have a Herms system with 2 pumps. My brewing partner and I have been contemplating spending the $ on a gas control panel, but $1k+ we can't justify the cost right now. Possibly doing a little automation could change our thoughts... So, we're contemplating connecting our herms pump to the extra A419 and submerge the temperature probe in the middle of the grain bed. We would run the HLT near mash out temps, allowing us do step ups easier and sparge water would be ready instead of ramping it up before the sparge. The pump would kick the herms on when falling below the mash temp desired. Our concern is the A419 cord doesn't look liquid tight and would temps up to 170 degrees screw up the probe? Is there a different probe we could purchase for this type of use? Thanks for any help or what you have done.

 

[day_trippr]

The A419 uses a PTC thermistor for the temperature probe, however Johnson does not provide the specific type of PTC used and there are a lot of types available.

That's likely not the biggest problem with the plan. Leaving wort in a hex at 170° will accelerate the enzyme denaturing process. If that happens often/long enough during the mash it's bound to affect the outcome, shifting the sugar production towards dextrins. Generally, not a good thing...

Cheers!

 

[instinct2]

Leaving wort in a hex at 170° will accelerate the enzyme denaturing process.

What if we did it our normal way of ramping up the HLT as the steps change and turn on the burner under the a MLT? I know it wouldn't be much different than how we normally do it, but hearing that pump shut off would be good for knowing when turn the burner off under the MLT. We occasionally over shoot the temps when coming up in temps. Partially the reason of wanting a little automation.

 

[day_trippr]

Regardless of how you go about it, you want to avoid "cooking" the enzymes during your early mash steps. Save that for ramping to mash out temperature (I assume you are fly sparging to even worry about that).

I'm not sure using a direct-fired MLT in tandem with a HLT/hex will be all that easy to manage, but I guess it's an option for helping with your temperature ramps.

Back to the temperature probe, you might be able to construct a long thermowell that'll fit the probe. Stuff the probe down to the bottom with a slug of thermal grease and it might track quick enough to work...

Cheers!