DIY electric kettle question WRT temp/PID

[bigmike86]

Question about using a water heater element and PID/SSR in the boil kettle.

Boiling point is 212 (assuming wort is same as water?) so how does a thermometer control the heating element when the liquid will never get over that point? I assume that a 240v heater element will scorch the wort if not throttled by the ssr, but I cant comprehend how and where to monitor the kettle temp that would provide the proper throttling if the liquid temp will never exceed 212.

Thanks for any input

 

[stevehaun]

For the boil, most people use the PID in manual mode which is typically expressed in percent power. The thermocouple doesn't really do anything but measure the temp while the PID is in manual mode.

 

[bigmike86]

Mind blown!!! So you really dont need a probe in the kettle? Mine already has an analog thermometer for cooling. I mean I guess it couldnt hurt but less holes = less leaks sometimes.

 

[stevehaun]

Some PIDs will not work without a temperature probe but in manual mode the probe does not have to be measuring the wort. You could measure your rectal temp while you are boiling your wort.
You could replace your analog thermometer with the temp probe (some can be immersed but some need a thermowell) and use your PID to measure the wort temp as you cool.

 

[bigmike86]

I would measure my rectal temp but most probes are far less than 4" diameter...hhehehe

 

[nobadays]

The reason for using a PID/SSR (with a contactor) is more often than not to control temps during the mash - esp with recirculation. Turning the element off and on is for maintaining temperature not to keep the wort from scorching (though it might if the element was just left full power throughout the boil...on that I don't know.) Prevention of scorching starts with using an ultra low density heating element.

As stevehaun pointed out most of us using a PID set it to manual during the boil. The percentage of power is actually percentage of time on/off. As an example - 60% = 60% on/40% off. The PID signals the SSR to turn the element on/off... actually the contactor that then turns the element on or off. You don't actually turn the element down as you would an electric range element when using a PID/SSR. With a little bit of experimentation you find what percentage gives you a good rolling boil without drastic boil-off.

The probe does have to be hooked up - but not necessarily measuring the kettle temp - for the PID to function. Mine is is attached to the return line in the lid which is set aside during the boil.

It might be possible to find a 4" thermal well if that will help with your rectal needs...

Cheers!