Mash Temperature Stratification

Hi Folks,

I use a mini-brew tun from Hobby Beverages with a RIMS. I have a RTD connected at the output of the RIMS and another connected to a second PID at the bottom of the tun (just to measure temperature). They are the same RTD from Auberins.

My issue is that I see a 20F difference between the liquid leaving the RIMS to the liquid at the bottom of the tun. This seems kind of extreme to me. I have insulated the tun using Reflectix (which I have found out is probably not the best insulator).

What is your take?

Bump. Nobody?

SO, during the whole process, the temps dont assimilate?

What is the temp going in, compared to coming out?

My setup is kind of similar, right after the heat exchanger is where I have the process control temp probe for the PID. I have a second probe in the middle of the mash tun. Once it gets up to temp they are both pretty much dead nuts on. and the PID is set to the mash temp.

I've found that if I run my RIMS system too fast I'll actually start cooling the wort. My return is a large sprinkler ring and I think that a lot of the heat put into the Mash is shed to atmosphere as it sprays down. If I slow it down to a trickle it has a much easier time maintaining and increasing temps.

Take the lid off of the thing though and temps drop like a brick.

The Pol said:

SO, during the whole process, the temps dont assimilate?

What is the temp going in, compared to coming out?

Click to expand...

Well, I don't have a thermometer or RTD on the outlet, just in the bottom of the mashtun, so I can't be sure but I assume it would be the same.

It just seems to me that 20 degrees is pretty wide.

JVD_X said:

Well, I don't have a thermometer or RTD on the outlet, just in the bottom of the mashtun, so I can't be sure but I assume it would be the same.

It just seems to me that 20 degrees is pretty wide.

Click to expand...

That is huge, yeah... if you are reciculating pretty fast, that seems nearly impossible.

The Pol said:

That is huge, yeah... if you are reciculating pretty fast, that seems nearly impossible.

Click to expand...

Pol. see what I said about spraying a large volume of liquid through the sparge arm? From watching mine it almost seems like heat is transferred to the air faster than it can put it into the wort.
Pardon my napkin figuring here:
say it is a 4500 watt element.
We have a flow rate of 1gpm.
So we are introducing 4500 WattMinutes per gallon.
Bump the flow rate up to 4 gpm and we are down to 1125 WattMinutes per gallon.
Take into account the number and size of the holes in the manifold and the distance to the grain bed and there is going to be energy lost to air due to contact area. If WattMinutes lost to air is greater than or equal to the energy going into the Mash then you will be heating mostly air, which will only heat the top of the grain bed.

I am not saying this is true but it is the only explanation I have to explain why my Mash refuses to heat if I use a fast flow rate.

If your return sits right on top of the grain bed then you can throw all that out with the trub

How does the MiniBrew thing return the wort?

I do have a 1/2" ID line that is my return/sparge line. It is also affixed inside the lid of my cooler MLT, so there is a lid, no spraying and it returns it directly to the mash.

I see what you are saying Code... definitive #s aside, that would release a lot of heat.

The Pol said:

How does the MiniBrew thing return the wort?

I do have a 1/2" ID line that is my return/sparge line. It is also affixed inside the lid of my cooler MLT, so there is a lid, no spraying and it returns it directly to the mash.

I see what you are saying Code... definitive #s aside, that would release a lot of heat.

Click to expand...

The minibrew link that was posted in OP shows a sprinkler type return option. Don't know if that is what he is using.

Yeah, I have no idea what the definitive numbers would be. I was using them to illustrate the inverse relationship between heat and flow. Glad it made sense to some one

CodeRage said:

The minibrew link that was posted in OP shows a sprinkler type return option. Don't know if that is what he is using.

Yeah, I have no idea what the definitive numbers would be. I was using them to illustrate the inverse relationship between heat and flow. Glad it made sense to some one

Click to expand...

It is the same principle that they use when applying de-ice fluid on aircraft. They are firing this stuff from 10-20 feet from the a/c surface. Doing so when it is 0F outside cools the fluid rapidly mid-air, which is why it has to be heated to a MIN of 140F prior to reaching the end of the spray nozzle. Makes complete sense.

The Pol said:

How does the MiniBrew thing return the wort?

I do have a 1/2" ID line that is my return/sparge line. It is also affixed inside the lid of my cooler MLT, so there is a lid, no spraying and it returns it directly to the mash.

I see what you are saying Code... definitive #s aside, that would release a lot of heat.

Click to expand...

There is a side return - for the RIMS - and a lid return for a sparge arm. I don't use the sparge arm when recirculating, just when sparging.