Temp Probe Positioning

[RAD]

I've done about 6 brews with my herms set up and i am struggling to keep a steady temp, i am getting a fluctuation of about 2.5 deg. i have changed my heat exchanger from a 10L pot with 15m copper coil & 1500watt heating element to a 3L tube with 5.5m(i think) stainless coil and 2000watt heating element. I'm not to sure which is better.previously i had the temp probe @ the outlet of the heat exchanger now i have it in the mash tun. I'm using RoHS digital temp controlers for my mash and sparge. I suppose my question is what can i do to steaddy my temp and keep it more stable and consistent?
View attachment 53947
View attachment 53948

 

[QldKev]

What Hy setting do you have your pid set too?

 

[fcmcg]

I've done about 6 brews with my herms set up and i am struggling to keep a steady temp, i am getting a fluctuation of about 2.5 deg. i have changed my heat exchanger from a 10L pot with 15m copper coil & 1500watt heating element to a 3L tube with 5.5m(i think) stainless coil and 2000watt heating element. I'm not to sure which is better.previously i had the temp probe @ the outlet of the heat exchanger now i have it in the mash tun. I'm using RoHS digital temp controlers for my mash and sparge. I suppose my question is what can i do to steaddy my temp and keep it more stable and consistent?

Can i ask why you have moved your temp probe ?
In my HERMS ( 10L pot with 2400 watt element and 8 ?m copper coil) , i have my probe placed on the outlet of the coil. From my understanding , this is the most reliable and accurate place for the probe.You are measuring the wort , exactly as it exits the coil...at its exact temp.Your mesuaring your temp it in its volume of wort..there is one problem , imho.By placing it at the outlet , your measuring EXACTLY what it is.
My pid is set to auto for my herms and i have the other one set to simple on/off for my HLT..
I'd suggest moving your probe back to the outlet of your coil ...Also maybe check your probes against a thermomiter that you know is accurate.
Not sure why your having problems...i get good stable temps and about 1 to 1.5 degree a minute rise when i have to raise temp for mash out...
MY humble 2c
Cheers
Ferg

 

[RAD]

Can i ask why you have moved your temp probe ?
In my HERMS ( 10L pot with 2400 watt element and 8 ?m copper coil) , i have my probe placed on the outlet of the coil. From my understanding , this is the most reliable and accurate place for the probe.You are measuring the wort , exactly as it exits the coil...at its exact temp.Your mesuaring your temp it in its volume of wort..there is one problem , imho.By placing it at the outlet , your measuring EXACTLY what it is.
My pid is set to auto for my herms and i have the other one set to simple on/off for my HLT..
I'd suggest moving your probe back to the outlet of your coil ...Also maybe check your probes against a thermomiter that you know is accurate.
Not sure why your having problems...i get good stable temps and about 1 to 1.5 degree a minute rise when i have to raise temp for mash out...
MY humble 2c
Cheers
Ferg

I think i might try that i have researched it and some people say to have it at the outlet and some say to have it in the grain bed very confusing i am also wondering if the size of my heat exchanger pot is to small. I put a thermometer in it to see what temp the water gets to before the element turns off and it gets to 81deg so i am thinking that that is the main cause of my problem. will try moving the probe before next brew and see how it goes.
Thanks Anthony

 

[RAD]

What Hy setting do you have your pid set too?

sorry for the late reply QldKev whats a Hy setting im fairly new to this game?

 

[QldKev]

I'm looking for the amount of temperature variation allowed before the unit will cut in to correct it. So in heating mode, if you set the controller to 66, and set the Hy to 1, then 66 - 1 = 65 so it will cut the heating element in at 65 and heat until it hits 66, before turning itself off. (a true PID will try and allow for gains etc and may tweak the numbers further, but you get what I mean)

If your running a stc-1000 it's the F2 setting, "Difference Set Value"

Check for a setting like this, otherwise post what unit you have and we can check the settings.


edit:
Also for the position I've always been told to use the hottest spot, being directly in the flow in the outlet of the Heat Exchanger.

 

[RAD]

I'm looking for the amount of temperature variation allowed before the unit will cut in to correct it. So in heating mode, if you set the controller to 66, and set the Hy to 1, then 66 - 1 = 65 so it will cut the heating element in at 65 and heat until it hits 66, before turning itself off. (a true PID will try and allow for gains etc and may tweak the numbers further, but you get what I mean)

If your running a stc-1000 it's the F2 setting, "Difference Set Value"

Check for a setting like this, otherwise post what unit you have and we can check the settings.


edit:
Also for the position I've always been told to use the hottest spot, being directly in the flow in the outlet of the Heat Exchanger

The controler i have is set to cut in at .3 of a deg either way i dont known the name of it. I think ist the residual heat in the exchanger that is macking the temp get higher than it should, the heating element has cut out but the temp still rises. I did put a thermometer in the exchanger and it gets around 81deg befor it cuts out. I am going to move my sensor to the outlet of the exchanger and see how i go.

 

[fcmcg]

The controler i have is set to cut in at .3 of a deg either way i dont known the name of it. I think ist the residual heat in the exchanger that is macking the temp get higher than it should, the heating element has cut out but the temp still rises. I did put a thermometer in the exchanger and it gets around 81deg befor it cuts out. I am going to move my sensor to the outlet of the exchanger and see how i go.
View attachment 53967

In your pic , your measuring the water bath...and the wort....there will be a difference...imho...don't forget that your wort is constantly being recirculated..and the water bath is static....this could account for one or two degree....
Also..is your controller a pid ? I'm not sure....can you auto-tune it ?
F

 

[AndrewQLD]

Sounds like your controller is either not pid or is not operating in that mode.

 

[RAD]

Sounds like your controller is either not pid or is not operating in that mode.

In the process of making a stainless steel fitting to house my temp probe in the outlet of my heat exchanger coil this is what it looks like still need to get it all welded.
I feel stupid asking this but what is PID
View attachment 54051

 

[mxd]

I feel stupid asking this but what is PID
View attachment 54051

it's a controller that "learns" how your system heats, so as it starts getting close to temp it will start to "toggle"the power to minimize the chance of overshoot.

stolen from

Proportional-Integral-Derivative (PID) control is the most common control algorithm used in industry and has been universally accepted in industrial control. The popularity of PID controllers can be attributed partly to their robust performance in a wide range of operating conditions and partly to their functional simplicity, which allows engineers to operate them in a simple, straightforward manner.

As the name suggests, PID algorithm consists of three basic coefficients; proportional, integral and derivative which are varied to get optimal response. Closed loop systems, the theory of classical PID and the effects of tuning a closed loop control system are discussed in this paper. The PID toolset in LabVIEW and the ease of use of these VIs is also discussed.

 

[RAD]

it's a controller that "learns" how your system heats, so as it starts getting close to temp it will start to "toggle"the power to minimize the chance of overshoot.

stolen from

Proportional-Integral-Derivative (PID) control is the most common control algorithm used in industry and has been universally accepted in industrial control. The popularity of PID controllers can be attributed partly to their robust performance in a wide range of operating conditions and partly to their functional simplicity, which allows engineers to operate them in a simple, straightforward manner.

As the name suggests, PID algorithm consists of three basic coefficients; proportional, integral and derivative which are varied to get optimal response. Closed loop systems, the theory of classical PID and the effects of tuning a closed loop control system are discussed in this paper. The PID toolset in LabVIEW and the ease of use of these VIs is also discussed.

Thanks for that might have to see if my controler is pid hopefully it is i dont realy want to redo my whole control box is there any wad ot seeing on the actual units?
Here are some other photos that i took of my temp probe fitting

 

[BlueSky]

Thanks for that might have to see if my controller is pid

Unfortunately it looks like they're not PID's... the lower one is marked 'ED330' and a quick Google search shows them to be STC-1000 type digital thermostats... >>LINKY<<

 

[QldKev]

I would reposition the probe first. I'm only running a stc-1000 on my HERMS and my RIMS. I was going to swap it over with the PID from the fermenting fridge, but have not found I need too. A PID will probably do the job better, but I don't get anywhere near 2.5 degree overshoots (unless I run the HERMS and RIMS together)


QldKev

 

[RAD]

I would reposition the probe first. I'm only running a stc-1000 on my HERMS and my RIMS. I was going to swap it over with the PID from the fermenting fridge, but have not found I need too. A PID will probably do the job better, but I don't get anywhere near 2.5 degree overshoots (unless I run the HERMS and RIMS together)


QldKev

Gonna try my next brew with my probe on the outlet of the coil and see how i go
Thanks for the info

 

[kjparker]

bit of a bump here.

I am in the process of putting my herms setup together, and have been considering where to put the probe as well.

My original thorught was to put it at the exit to the coil, but on thinking about it, thought that maybe I should be putting it in the fitting I use to return the wort to the MLT, this way any heat loss in the piping is accounted for.

Am I way off track?

 

[jimmyjackpot]

bit of a bump here.

I am in the process of putting my herms setup together, and have been considering where to put the probe as well.

My original thorught was to put it at the exit to the coil, but on thinking about it, thought that maybe I should be putting it in the fitting I use to return the wort to the MLT, this way any heat loss in the piping is accounted for.

Am I way off track?

Opinion seems to be quite divided on this issue. I have recently setup a HERMS system and had the same question when it came to temp probe placement. I did some research and did not get any definitive answers as to where the probe should be placed.

I ended up placing the probe at the exit of the HERMS coil as I wanted to measure the wort at the hottest point. I was concerned that measuring temp in the mash or wort return may result in the coil overheating the wort, especially when ramping temps up.

 

[kjparker]

Opinion seems to be quite divided on this issue. I have recently setup a HERMS system and had the same question when it came to temp probe placement. I did some research and did not get any definitive answers as to where the probe should be placed.

I ended up placing the probe at the exit of the HERMS coil as I wanted to measure the wort at the hottest point. I was concerned that measuring temp in the mash or wort return may result in the coil overheating the wort, especially when ramping temps up.

I might try it both ways It'll just mean swapping a bung.

I guess though, if the return hose is insulated, the heat loss should be minimal.

 

[Yob]

Opinion seems to be quite divided on this issue. I have recently setup a HERMS system and had the same question when it came to temp probe placement. I did some research and did not get any definitive answers as to where the probe should be placed.

I ended up placing the probe at the exit of the HERMS coil as I wanted to measure the wort at the hottest point. I was concerned that measuring temp in the mash or wort return may result in the coil overheating the wort, especially when ramping temps up.

From what Ive read in THIS THREAD the exit of the HERMS is correct.

I made the same mistake with the first run but quickly fixed it in subsequent runs

:icon_cheers:

 

[fraser_john]

<snip> I wanted to measure the wort at the hottest point. I was concerned that measuring temp in the mash or wort return may result in the coil overheating the wort <snip>

Flamesuit On!

Yup, there would be a risk that measuring anywhere else other than the HEX exit could result in enzymes being denatured. By measuring the outlet, you are ensuring that the wort, with most of the enzymes in it, is at the temperature you require.

<edit for really poor grammar.>