Lawrence Brewers Guild

Hey all you helpful builders,

For a thermowell I am planning on using a piece of Cu++ tubing that has been beat down and soldered on one end.
I plan to insert my probe into this tube (it fits, I checked).
The "well" then goes through the lid.
This seems to easy. Is there any dangers that I should be aware of?

Also, if I am using an electric element for my HLT but only to heat strike and sparge water (at this time) I am wondering if I will have problems with stratification. Or are these problems mostly associated with heat exchange coils.

thank you for your consideration

Hey you've done some research, Good job.
Personally i think your thermowell work work fine. My only question is does the sensor go in tight or is there a alot of sloppy space in between the thermowell walls and the sensor? If its not real tight, you can get some off readings because of the air space. That's why some folks use the contact goop inside their thermowells.
Also, you will get stratification around coils no matter how you heat the water. I will get Stangbat over here to answer more of your questions as he is the electric brewer extraordinaire. Hopefully he will post a pic of his rig. Its an electric marvel.

Andy has pointed you straight on the non contact of the thermistor on your controller.

In the industrial world, silicon oil or grease would be preferred for the contact media for the temperature probe to the thermowell. Most silicon greases and oils will get an FDA approval for use in the food industry, check the label. Super Lube as I remember has such a rating and I believe that Ace Hardware carries the brand.

Since you most likely have a vertical well, glycerin would also work quite well since it is an oil the air pocket would disappear plus it can be consumed as a food product. If you tube is close to the thermistor size, you will only need a few drops for the contact surface. The temperature of beer producing would allow a low temperature oil. Vegetable oil would also work but it oxidizes and gets gummy.

A good contact surface will make a great difference in the response time of your temperature reading.

I've always been concerned about my probe and my thermowell. The Thermowell is a simple piece of SS I bought from the hardware store with a good packing of food grade silicone on one end, but it's diameter is larger than the probe on my Love controller.

What are the down sides to using any of the things Chris listed as mediums to put into the well? What about bacteria build up? Does the medium have to be cleaned out after every use? Every X uses?

I've been told that the probe on the Love controller shouldn't be submerged in liquid (don't remember who, I tend to drink a lot), though it doesn't say this on the documentation that came with the controller, but it also doesn't say its waterproof either. Will any of these mediums have an adverse affect on the probe itself? It seems to be covered in a textured rubber (mmmmm, sexy), and I guess I could add my own spray-on liquid plastic/rubber to assure a water seal, but will this affect the probes ability to read the proper temps?

also
why is the sky blue?
what is the air speed velocity of an unladen swallow?
how many licks does it take to get to the center of a tootsie roll tootsie pop.

Any input to the real questions would be appreciated.

The oil/grease does not have to be replaced. If all is going correctly, it will never enter your beer. But assuming that you should have a leak in the thermowell, you would not want an ingredient leaking into your beer that would do you harm.

The oil/grease is just a conductor between the well and the probe without the insulation properties of air, since air is not a good conductor of heat. As long as the grease/oil has a greater boiling point of the liquid being measured, all is fine. Silicone and glycerin are mainly used because of the high boiling point and non reactive with the process. Glycerin would not be used in a Nitric Acid area, but that is not a concern with what we are doing.

As far has a Thermocouple, RTD or a thermistor, the oil/grease should not have much of an impact since the media does not have a good conductivity rating (doesn't pass electricity).

All is good. Just make sure that the water/wort has some agitation so that the temperature is equalized across the area of the liquid. The area around the cooler/heater will also have the greatest delta T because of the temperature difference. The farther away from the delta T, the less of a difference. So, it you have a heater in the center of a vessel, the temperature will be greater in the center and less towards the edge. If you create a whirlpool, the temperature will still be greater in the center and cooler towards the outer section. But if you create an outside vortex that doesn't create a center vortex like a tornado then the liquids will equalize to a certain degree and give a more even/average temperature.

Hope all this makes a knowledge to the brain .

This is the same as my thermowell for the EHLT. You can use a big spoon or a stir motor to disrupt the stratification - it will happen.

My Ranco probe has a sloppy fit (it's set for a 1df differential). When heating it reads 2df below the real temps but it does equalize once it hits whatever I have it set at. Works OK at my place.

klickcue wrote: ***The oil/grease is just a conductor between the well and the probe without the insulation properties of air, since air is not a good conductor of heat.


***But if you create an outside vortex that doesn't create a center vortex like a tornado then the liquids will equalize to a certain degree and give a more even/average temperature.

Hope all this makes a knowledge to the brain .

I would certainly try the probe a few times 'dry' just to see how off it may be. if it is a consistent amount every time then that can be accounted for without having to lube your probe all up--that was for you Bill. The life of that probe will be a lot longer if kept dry as opposed to packed in grease, but years and years in grease I'm sure.



Hmm, I like that outside vortex idea. never gave it much thought before.