MLT temperature probe depth?

[dannedry]

How deep into the grain bed (horizontally) should by temperature probe be inserted? I am using weld-less fittings and keggles. The bi-metal thermometers typically come in 2.5", 4", and 6" probe lengths.

Thanks for your input!

 

[Catt22]

IMO, the ideal location in order to gauge the average grain bed temperature would be half way to the bottom and half way between the center and the outer wall of the mash tun. I use a fully adjustable vertically mounted thermowell for this. I no longer use the bi-metal dial type thermometers as I found them to be both unreliable and inconsistent though their range. I do use a traceable glass lab thermometer to check and/or calibrate the digital thermometer as I feel it is the least susceptible to error of any any.

 

[dannedry]

IMO, the ideal location in order to gauge the average grain bed temperature would be half way to the bottom and half way between the center and the outer wall of the mash tun. I use a fully adjustable vertically mounted thermowell for this. I no longer use the bi-metal dial type thermometers as I found them to be both unreliable and inconsistent though their range. I do use a traceable glass lab thermometer to check and/or calibrate the digital thermometer as I feel it is the least susceptible to error of any any.

That's kind of what I was thinking... the 4" probe would get me in between the center and the wall of the keggle. How is your temp probe adjustable vertically? Do you drop the probe down through the top of the MLT? Thanks Catt!

 

[Catt22]

Yes, I have the thermowell suspended vertically from a wooden cross bar over the mash tun. The thermowell is actually just a section of copper pipe capped on the bottom. The pipe can be moved vertically and locked in place with a thumb screw. The temp probe of the digital thermometer goes down into the pipe touching the cap at the bottom. Not very high tech, but works perfectly for me. The adjustable feature is important for the varying batch sizes.

 

[Cpt_Kirks]

Timely discussion, I just started on my new MLT and was thinking about the thermometer probe length.

Does anyone make a digital probe thermometer with 1/2" mounting threads?

 

[dannedry]

Yes, I have the thermowell suspended vertically from a wooden cross bar over the mash tun. The thermowell is actually just a section of copper pipe capped on the bottom. The pipe can be moved vertically and locked in place with a thumb screw. The temp probe of the digital thermometer goes down into the pipe touching the cap at the bottom. Not very high tech, but works perfectly for me. The adjustable feature is important for the varying batch sizes.

I like that idea... what diameter pipe? Does the probe fit snuggly in the pipe? Thanks.

 

[Catt22]

I like that idea... what diameter pipe? Does the probe fit snuggly in the pipe? Thanks.

The DIY thermowell is ordinary 1/2" rigid copper pipe. No, the probe is a cheap type "K" bare junction thermocouple and it does not fit snugly in the pipe at all. I push it to the bottom and it is held in place by a section of dowel. The response time is very fast as the copper conducts heat so well.

 

[dannedry]

The DIY thermowell is ordinary 1/2" rigid copper pipe. No, the probe is a cheap type "K" bare junction thermocouple and it does not fit snugly in the pipe at all. I push it to the bottom and it is held in place by a section of dowel. The response time is very fast as the copper conducts heat so well.

Excellent... I think I will go this rout. What kind of thermometer do you use? Panel mount displays? Thanks Catt!

 

[dannedry]

Timely discussion, I just started on my new MLT and was thinking about the thermometer probe length.

Does anyone make a digital probe thermometer with 1/2" mounting threads?

I've been searching thermometers, both bimetal and digitals, and haven't seen much as far as digital probes with the threads. A thermowell may work for you though...

 

[ILuvIPA]

Bobby M has a solution to convert any digital probe - use a compression fitting (1/2" mpt to 1/8" compression.) Remove/discard the compression ferrule and replace it with a stack of 5-6 tiny O-rings (#60 size works.) The compression cap will compress the O-rings & seal against your digital temp probe. I had to add a small flat washer under the cap (#8 stainless flat washer.)

It works (Thanks Bobby M!) I think the whole thing cost about $6 bucks at Lowes.

Timely discussion, I just started on my new MLT and was thinking about the thermometer probe length.

Does anyone make a digital probe thermometer with 1/2" mounting threads?

 

[Catt22]

Excellent... I think I will go this rout. What kind of thermometer do you use? Panel mount displays? Thanks Catt!

Here's a pic of the thermometer and thermowell:

I have this Cole-Parmer thermometer: http://www.coleparmer.com/catalog/product_view.asp?sku=9121045

I have since acquired some different thermocouples for the thermometer. The type "k" thermocouples are very cheap and available in a wide variety of configurations. I prefer the plain wire, bare junction type for this application. Ebay is a good source for those.

 

[Cpt_Kirks]

Bobby M has a solution to convert any digital probe - use a compression fitting (1/2" mpt to 1/8" compression.) Remove/discard the compression ferrule and replace it with a stack of 5-6 tiny O-rings (#60 size works.) The compression cap will compress the O-rings & seal against your digital temp probe. I had to add a small flat washer under the cap (#8 stainless flat washer.)

It works (Thanks Bobby M!) I think the whole thing cost about $6 bucks at Lowes.

Rubber O-rings?

Also, who makes thermowells that work with weldless keggle fittings?

 

[Bobby_M]

Yeah, I got the idea of replacing compression fitting ferrules with Orings based on some previous DIY underwater housing control rods. If you have a digital probe that is stainless, you don't need to jam it in a thermowell. The actual probe goes through the wall and liquid is stopped by the compression fitting.

 

[Cpt_Kirks]

Yeah, I got the idea of replacing compression fitting ferrules with Orings based on some previous DIY underwater housing control rods. If you have a digital probe that is stainless, you don't need to jam it in a thermowell. The actual probe goes through the wall and liquid is stopped by the compression fitting.

So, I need a 1/8" ID, 1/2" OD SS compression fitting?

Who carries that, and do you have a part number?

 

[dannedry]

Yeah, I got the idea of replacing compression fitting ferrules with Orings based on some previous DIY underwater housing control rods. If you have a digital probe that is stainless, you don't need to jam it in a thermowell. The actual probe goes through the wall and liquid is stopped by the compression fitting.

Another way to go is using a straight 1/4" compression to NPT fitting, slip the probe into a short piece of 1/4" tubing, and then use the compression ferrule on that tubing that your probe has been run through... not sure that this is any easier or less parts than the o-ring method, just another option. I am a test engineer, and use this method to insert digital temp probes into our 100psi compressed air test rigs.

 

[dannedry]

Yeah, I got the idea of replacing compression fitting ferrules with Orings based on some previous DIY underwater housing control rods. If you have a digital probe that is stainless, you don't need to jam it in a thermowell. The actual probe goes through the wall and liquid is stopped by the compression fitting.

And Bobby, I saw your write-up in BYO! Very cool. Congrats.

 

[BrewBeemer]

Catt, I was thinking use SS tubing with a press fit plug also soldered at the end plus sink the probe in SSR heat sink paste for quick heat transfer.
Food grade silicone to seal the probe wires coming out of the SS tubing.
No holes for probes and sight glass into the keggles.

 

[Catt22]

Catt, I was thinking use SS tubing with a press fit plug also soldered at the end plus sink the probe in SSR heat sink paste for quick heat transfer.
Food grade silicone to seal the probe wires coming out of the SS tubing.
No holes for probes and sight glass into the keggles.

I considered doing something similar at one time, but after some testing I concluded that nothing that fancy was really necessary. The copper thermowell conducts the heat very well for a fast response time. The bare junction thermocouple is in direct contact with the copper cap at the bottom. I have not found it necessary to use a thermal paste to improve on this. I also did not want to seal the thermocouple wire into the tube in any way. This allows for replacing the thermocouple easily and quickly if need be, which it never has so far. I also wanted to be able to break the whole thing down for easy mobility and storage. I do the group brew thing away from home occasionally, so this makes transport much less of a hassle. The thermocouple could actually be used directly in the mash, but I wanted to be able to control where it was actually positioned in the grain bed.

 

[dannedry]

Here's a pic of the thermometer and thermowell:

I have this Cole-Parmer thermometer: http://www.coleparmer.com/catalog/product_view.asp?sku=9121045

I have since acquired some different thermocouples for the thermometer. The type "k" thermocouples are very cheap and available in a wide variety of configurations. I prefer the plain wire, bare junction type for this application. Ebay is a good source for those.

Thanks for the pic Catt! Is this your thermometer setup for your HLT and Boil Kettle as well? I just found a new two channel thermocouple from Thermoworks... $69 and uses two K type probes. This way I can monitor HLT and MLT at the same time, using your DIY thermocouple. What do you think? I attached the link below...

http://www.thermoworks.com/products/handheld/TW8060.html

 

[Catt22]

Thanks for the pic Catt! Is this your thermometer setup for your HLT and Boil Kettle as well? I just found a new two channel thermocouple from Thermoworks... $69 and uses two K type probes. This way I can monitor HLT and MLT at the same time, using your DIY thermocouple. What do you think? I attached the link below...

http://www.thermoworks.com/products/handheld/TW8060.html

I use it on the MT when the RIMS is in operation and then I move it to the BK when chilling. I pump the hot wort through a CFC and back to the BK in a continuous loop when cooling. I also use a 5 gallon bucket to "park" the whole thing when stirring the mash or for the dough in. I use a 50 qt Ice Cube cooler as my HLT and once up to temp it holds it well, so I don't monitor it continuously.

IMO, everything from Thermoworks is considerably overpriced. The unit you are looking at is very nice, but you must buy the thermocouple probes separately and it doesn't even come with a carrying case or pouch. There's probably shipping charges too. I never buy anything from them. You can do much better elsewhere.

Check out this deal on a dual probe digital: http://cgi.ebay.com/2-K-Type-Digita...878?pt=LH_DefaultDomain_0&hash=item45f81fef56

 

[ILuvIPA]

Don't have the part number but both Lowe's & Home Depot have it on the shelf (in brass) It's an adapter fitting: 1/2" male pipe thread on one side to fit your welded kettle port and the compression fitting on the other side. I'm pretty sure I've seen it on bargain fittings in SS if you prefer. I paid about 5 bucks for the brass fitting and another buck for the pack of O-rings (yes, black rubber.)

Edit: and thanks again Bobby, quick inexpensive way to put my digital probe through the kettle wall!

So, I need a 1/8" ID, 1/2" OD SS compression fitting?

Who carries that, and do you have a part number?