Heat Exchanger Temperature Probe Placement

[gbrewer]

Hey guys,

I just purchased my ECC unit and am excited to receive it. I currently have a brutus style unit that I have designed but added my own touches to. This includes an actual 24 volt gas value instead of the "ASCO" valve. I will be heating my HLT using LP gas. I will also be adding a heat exchanger to my MT.

My question pertains to the placement of the temperature probe in relation to the Heat Exchanger. Where is the best placement and why?

I was thinking that I would continue to place my temperature probe half way in my mach tun for the reading. I figure that I am getting more of a "true temperature" of the mash versus the temperature of the hot wort as it comes out of the heat exchanger. I have also seen placement of the temperature probe on the exit side of the heat exchanger.

Thoughts?

[bsfixit]

I can change where I put the temp sensor in my system. I first tried HE outlet. next I may try mash tun outlet, before the pump as it goes into HE . or both.
subscribing ... I want to see thoughts on this too.
Brett

[np0x]

I feel quite strongly that placement of the temperature probe anywhere OTHER than the HE output is going to result in over heating the mash. I am also am a strong proponent of getting the strike water temps right EVEN if you are using a HERMS/RIMS as the ability to get the entire mash to a specific temperature is challenging if you aren't willing to OVER heat a portion of the mash. When raising the temperature there is always a gradient of temperature across the mash tun(vertically) that is the result of the hoter return transferring heat to the material in the mash tun coupled with heat loss and absorption as the heated mash liquid flows through the grainbed.

I have a temperature probe on both my HE input and output side during temperature transitions there is as much as a 10F differential (say on mash out steps) during normal mashing the differential drops to 2-3F and this could be further diminsihed once i put some(any really would help) on my keggle mashtun.

[gbrewer]

I have read the arguement of placing the temperature probe on the output side of the HE. I really don't understand it. Isn't the element a simple "on / off" control? How is someone able to accurately automate the temperature of the mash if the temperature they are using is coming directly from the heating element? Wouldn't this typically show a higher temperature when the element is on than what is inside the mash tun? It appears to me that this would cause the element (based on the temperature) to shut off prior to the temperature inside the mash tun reaching your target.

I understand the issue with overheating as well. I had my temperature probe set in the mash tun and really had to watch the temperature using my old love controls. If I set it at the target temp (example 152) , the "rise" of the temp would continue well past what my target was if I tried to stop on the target (152). I had to stop the temperature at around 144 from where my probe was set. By the time the heated wort would reach the probe, it would end up near the target.

[bsfixit]

I had the same issue on my last brew.. the mash temp was quite a bit lower than the temp exiting the HE.
I posted in another thread. I am going to try a higher strike temp and insulate the mast tun. so the heaters
do not have to work so hard to maintain the mash temp. I also want to try changing which way the wort flows
through the HE. Instead of the wort going straight down to the bottom of the coil then heated as it goes up
and out the coil . I am going to revers the wort flow. it goes in the top of the coil down then up and out.
just to see what the difference is.. If any
Brett

[microbusbrew]

I have a question regarding temperature probes. I'm still in the process of building my HERMS and I bought two of the probes available from ECC. I'm installing one in my HLT and one in my heat exchanger to monitor the temp of the water in the heat exchanger itself. As far as measuring the temperature of the wort exitting the exchanger, I was thinking I'd somehow attach a thermistor to the outside of the copper tubing on my heat exchanger. This would be your basic epoxy encapsulated 10K ohm thermistor that you'd find at an electronics store. I would use some thermal paste between it and the copper tubing and secure it in place with electrical tape, heatshrink tubing, or something similar. Because the copper tubing is such a good thermal conductor, I'm assuming I should be able to measure the temperature of the wort without having to install a temperature probe inline (e.g. in a tee-fitting). Has anyone tried something like this and what where your results? I'm thinking maybe put a little foam wrap around the section of tubing to make sure I don't get false readings on windy/cool days.

[np0x]

I think that's a really interesting(and good idea), i would insulate the crap out of it, but I think you would be good. You might get a little bit of lag, but I can't imagine it would be much and the PID would figure it out after a couple of response cycles as I understand them.

You definately want to be measuring the wort AFTER it has gone through the heat exchanger, anything else will result in over heating your wort(and enzymes) which will result in not the mash profile you think you are getting.

[missing_link]

I'm on about revision 6 of my electric system.

Let me give you a little history of my learning curve.

I started with heating element in the mash tun = burned an element out and ruined the batch

I moved to an element in a 1 gallon cooler with Love Control. The probe for the LOVE was at the mash outlet just like the Brutus. Heated the water with a pump keeping things moving to my strike temp. Doughed in and adjusted LOVE to mash temp. All was well until the LOVE called for heat. It turned the element on and kept it on until the outlet temp of the mash tun reached the set point. Then I watched in horror as the temp in the mash continued to rise up to 168 even though the element was off!!! Talk about over shoot!!

I then moved the element to a PVC tube and measured the temp as the wort leaves the heat exchanger. I also measure the temp of the wort leaving the mash tun with a digital thermometer. Using this set-up with my pump unrestricted, I am able to maintain 1 degree accuracy on the mash. The HEX outlet and the Mash Outlet are within 1 degree of each other. Often times they match. As the mash loses temp, the LOVE calls for heat and warms the wort in the HEX up to the set point and shuts off. In practice it seems the HEX cycles on for a few minutes and off for a few during most of the mash.

I then went to a copper HEX but kept the set-up the same.

I am now going to the BCS-460 and I have everything stuffed into a tiny box with a handle on it. Pumps, HEX's and all the electronics. My entire brewery is in a box the size of a small tool box. All I have to do is set it on the floor, plug in 2 extension cords, hook up 4 hoses and connect my laptop and I am brewing. This should be complete this weekend.

Linc

[datamike]

We need pics!

Michael

[missing_link]

We need pics!

Michael

By this weekend I should be far enough along to take some pics. The box is wood right now but once I get everything set and tested I am going to have a box made out of diamond plate aluminum.

Linc