Temp Control Issues

[ryan810cows]

Hello All!

I have been working on my new Electric Brew Rig for some time now and just yesterday was able to fire it up and do a dry run. I noticed that my temp was lagging (about 10-20 deg F). When it was a GOOD boil, temp was around 200 deg F at best. I didn't wait around to see if it would keep going b/c it slowed down to a crawl at that point. I also used a kitchen thermometer and put it right in the water. It was reading higher then my RTD. Granted, the RTD was rising, just lagging way below the thermometer.

I am using this thermo well:
TW025-01 - THERMOWELL 0.26in ID x 2-3/4in 304SS 1/2in FNPT 1/2in MNPT (KEGGLE)

And this RTD:
RTD1-D08L10-01 - RTD PT100 3-WIRE 0.263in DIA x 8in 10ft STRANDED WIRE

Here is my setup

Here is my full Rig... So Far... Haven't Brewed yet though! LOL

Here is the Back Side

Here is the Panel up close!

So after all that being said, I have read that putting some Thermal Grease on the end of the RTD in the Thermal Well will make things better.

I am also don't know if I need to change my temp set up now. Is a Thermowell not a good idea? I wanted to have the ability to remove the RTD without dumping wort or needing tools.

I'm open to any and all advice or criticism.

Thanks guys!

 

[doug293cz]

Sounds like you have a waterproof RTD probe inside a thermowell. There is probably little to no contact between the RTD probe and the inner wall of the thermowell, so you have an insulating layer of air. This will severely retard the response time of the RTD, and may also result in a significant offset in the reading. The offset would be due to thermal conduction along the shaft of the RTD probe, which will keep the probe cooler than the walls of the thermowell.

You could put thermal grease in the thermowell, but if you do you will NOT want to be taking the RTD probe in and out of the thermowell. Thermal grease is incredibly messy, and tends to get everywhere.

Best bet is putting the RTD directly into the vessel. With a compression gland & o-ring, you could partially withdraw the probe from the vessel without leak issues.

Brew on

 

[ryan810cows]

Thanks for the reply!

After a few sleepless nights thinking about this (I know, I have issues), I have decided to ditch the well and get a probe. I'll use a nylon ferrule and a compression fitting combo!

PROBE

FERRULE

COMP. FITTING


Anyone see any issue with my (yes, it's redundant) analog thermometer probe just barely passing into the kettle? Does it REALLY have to be a few inches into the kettle or is anywhere OK?

 

[doug293cz]

If the analog thermo is just to give you an idea of where things stand, and not being used for precise control, then positioning is not critical. Since you will have two thermometers, you can check how they track and mentally compensate for any offset in the analog due to placement.

Brew on