thermowell keggle probe insertion length

[billtzk]

For you fluid and thermal dynamics knowledgeable people out there, does water in a pot heat up evenly? I'm mean in large volumes like 12 or so gallons of water in a half barrel standard straight-sided keggle at a temperature less than boiling?

Specifically I'm talking about a natural gas jet-burner fired keggle HLT where I want to heat water to strike and mash out temps short of boiling, how much variation would I see without stirring if I take a reading near the top, middle, or bottom, at the center and near the keg wall, of a 12 gallon volume of water?

I'm going to put a 1/2 inch coupling in my HLT and screw a threaded thermowell into it so I can insert a Love temp controller probe. I know I need the probe near the bottom of the keggle as it wouldn't do much good if the volume of water dropped below it. I plan to put it two inches or three inches up the side of the keg. But I'm also trying to decide what insert length I need. A 2.5 inch would barely stick into the HLT. An 8 or 9 inch length would reach to the middle of the keg. They are available in many incremental lengths from 2.5 inches and up at progressively higher cost, and I don't want to buy a six inch probe if a 2.5 will be adequate.

 

[passelin]

I don't have experience with any jet fired burner and my setup is keggle with an electric element. I do find a large stratification of temperature between above and below the element. But the temp is relatively constant above the element. You should not experience this with the heat source on the very bottom. I would guess that the temperature would be fairly consistent as the natural mixing and flow of the fluids. I would recommend measuring the temps at various water levels if you have the equipment.

As for probe length, i would go for the shorter one as I can see the longer one getting in the way or smacking it while stirring or something like that.

 

[billtzk]

Thanks passelin. I went ahead and ordered a six inch thermowell. Since this is the HLT and not the boil kettle or the mash tun, I don't think it'll be in the way.

 

[Bobby_M]

There will be stratification no matter where the heat source is. My probe goes all the way to the center of the keg, maybe 4" off the bottom and it definitely reads hotter than the overall average temp of the 12 gallons. You can see that a quick stir will drop the reading a good 5-10 degrees.

The only solution can think of is to stir it every once in a while or recirculate to whirlpool.

 

[BuffaloSabresBrewer]

Why not just stir?

 

[billtzk]

Thanks for the confirmation Bobby_M. That's about what I expected to hear.

Yep, I'll recirculate it, at least while I'm not sparging. That's the easiest solution.

 

[Bobby_M]

I guess automation is a reason not to stir. If you're trying to use a temp controller to get to a perfect set temp, you want the probe to reading the real deal.

 

[korndog]

Bump.

I am trying to decide where to put my Thermowell on my HLT for Brutus 10 I am building. Lonnie has his in the lid, but I am considering B3's short (2.5")one with 1/2" threads towards the bottom of the tank. If I am recirculating, I imagine I would get good readings. Any advice for this setup would be appreciated.

KD

 

[Boerderij_Kabouter]

I setup my HLT like this:

8" thermometer 4 inches from keggle bottom
bulkhead with ball valve also 4 inches from the keggle bottom

With this arrangement I figure that the temperature right at the exit of my ball valve is the temp that the thermometer tells me. The tip of the temp probe is only ~2 inches away from the outlet.

I brew indoors and have found that my keggle only looses a couple of degrees over an hours time. As long as I keep the lid on I am not too worried about temp stratification.

Cheers