Herms temp monitoring location

[helterscelter]

I'm doing a brew today and I got to thinking about how I monitor my mash temperature.

I have a keggle gas fired herms set up. Typically I heat my hlt to be hotter than my mash temp and recirculate through the herms coil the whole mash. I measure the temp using an igrill 2 Bluetooth temp monitor and some very long probes. Typically I have one probe high in my mash tun and one right against the domed false bottom. I typically see some difference in the temp readings but not much. A couple degrees or so.

Today I decided to put the upper temp probe Right in the outlet hose coming from the herms coil. It read almost 10f higher than the mash sensor. Somewhat this makes sense to me. The wurt is coming from the coil would be hotter.

This made me wonder where the proper measurement location is. Should I be trying to control mash temp based on the temp coming out of the herms, The middle of the grain bed, the temp coming out of the mash tun ball valve??

I'm seriously considering going full automation on the mash temp control.. but would still need to know where to measure the target temp from...

 

[day_trippr]

There are likely many ways to do it, but fwiw, I control my (gas fired) HLT temperature based on the HEX output, then I adjust the HLT "set point" and the recirculation rate to get the mash to the desired temperature.
I brew indoors so my rig isn't subject to challenging conditions (wind/cold/both) so I typically have the HLT set 1.5-2°F above the mash target as measured through the full mash depth (I have one of these) and the system just purrs along without much intervention....

Cheers!

 

[helterscelter]

There are likely many ways to do it, but fwiw, I control my (gas fired) HLT temperature based on the HEX output, then I adjust the HLT "set point" and the recirculation rate to get the mash to the desired temperature.
I brew indoors so my rig isn't subject to challenging conditions (wind/cold/both) so I typically have the HLT set 1.5-2°F above the mash target as measured through the full mash depth (I have one of these) and the system just purrs along without much intervention....

Cheers!

What is a HEX output?

 

[day_trippr]

Heat EXchanger. What you called a "coil"...

Cheers!

 

[newtobrew1981]

The way i have mine set up is the same as the electric brewery's. I can keep my mash temp within a degree of my hlt. And in my opinion the best place would be the exit out of the mash tun and outlet of the hlt

 

[newtobrew1981]

Controlling a consistent temp in your hlt should give you a consistent temp in your mash tun

 

[jekeane]

Your hlt should only be 1-2 degrees above your mash temperatures.

You can measure at either the return to the top of the mash or at the output of the mash.

A measurement at the mash output will take longer to read within 1 degree of your hlt temperature because you need to heat the grain bed before getting to that probe.

A measurement at the return to the mash will show you your correct temperature from the hlt. However, you will still need to keg the bed temperature adjust as the wort runs through.

Either place will work assuming good flow rate and a consistent hlt temperature with a degree or two of you mash temperature.

You will have under attenuated beers if you run you hlt 10 warmer than your target temperature.

 

[Smellyglove]

Controlling a consistent temp in your hlt should give you a consistent temp in your mash tun

This depends on flowrate and coil length/diameter. If adjusting on the oulet of the HEX, then the probe is "in the loop", if adjusting the HLT then you have to take flowrate and coil into account as you'll use the water in the HLT as a medium.

 

[helterscelter]

Your hlt should only be 1-2 degrees above your mash temperatures.

You can measure at either the return to the top of the mash or at the output of the mash.

A measurement at the mash output will take longer to read within 1 degree of your hlt temperature because you need to heat the grain bed before getting to that probe.

A measurement at the return to the mash will show you your correct temperature from the hlt. However, you will still need to keg the bed temperature adjust as the wort runs through.

Either place will work assuming good flow rate and a consistent hlt temperature with a degree or two of you mash temperature.

You will have under attenuated beers if you run you hlt 10 warmer than your target temperature.

Under attenuation is exactly what I've been fighting the last couple brews. Damn. Wish I had asked earlier.

Fantastic information. Thank you

 

[helterscelter]

This depends on flowrate and coil length/diameter. If adjusting on the oulet of the HEX, then the probe is "in the loop", if adjusting the HLT then you have to take flowrate and coil into account as you'll use the water in the HLT as a medium.

I have a 25ft 3/8od stainless HEX in my hlt. Typically I get good flow rate on the recirculation side, though the 3/8 does restrict things a bit. I have riptide pump grads and so can control the flow rate pretty easily (got them mostly for fly sparging. Ball valves work fine but are a pita).. what flow rate should I be looking for while recirculating the mash?

I may change out the 3/8 for 1/2 but I'll probably have to start adding Rice hulls if I do. The grain bed already gets a little compacted if I recirc wide open. I suppose the 1/2 would give me better heat transfer as well so wouldn't necessarily take as long to raise temps...

 

[Smellyglove]

Dial back your restriction valve. You don't need to add rice hulls. Your flow should be no greater than what your grainbed and false bottom can handle. It varies with grist sizes and if you use a lot of wheat or such. Just poke a mash paddle or something into the grain bed and you'll get a feeling of what it should feel like when it flows good, and how it feels before you go stuck. Your target is the "spaghetti-feeling" you'll notice it has when it flows good

@helterscelter

 

[newtobrew1981]

With your I'd of tubing and length I would definitely try reducing your flow.

 

[helterscelter]

Quick update.

I moved my temperature monitoring to the output side of my heat exchanger using a thermowell and throttled my recirculation pump flow quite a bit.

I also kept a thermometer in the mash like I had been doing before.

This time i was successful in regulating my mash temp +-1.5f which is a huge improvement.

I'm definitely going to go down the road of automating the temp control, since I'd rather not fiddle with the gas valves the whole time. But I'm feeling much better about the whole measurement process after this last brew.

Thank you so much for all the help!