Many PID controllers are available on the market. The most popular PIDs in the homebrewing community are made by Auber Instruments; however, a plethora of chinese knock-offs are available on Amazon and Ebay. Because of the cost involved with shipping and VAT charges, I decided to go with the Sestos D1S-VR-220 to control my Igloo Cooler RIMS Brewing System. The Sestos D1S PID is one of the aforementioned knock-offs. Rumour suggests that it is a copy of the Auber SY 235x models. In the following paragraphs I will explain how I tuned my Sestos D1S to work with my RIMS system, and dealt with problems due to an oversized RIMS element.
The Sestos D1S PID
The Sestos D1S PID is used in my system to control mash temperatures. It does so by predicting the amount of power the element needs to put, and keep the wort within a particular temperature range. This prediction is based on a number of variables, including Proportional, Integral and Derivative variables. The proportional, integral and derivative (and control period, more on this later) variables need to be specified, or tuned in order for the PID to be able to accurately predict the amount of power the element needs.
Now, I’m no engineer, and at first this all seemed very confusing. Luckily, the Sestos D1S PID has an ‘auto-tune’ feature in order to achieve the task of tuning these variables. Simply run the auto-tune feature and your set, right? Sort of. Not only are the Sestos D1S PID instructions a pile of rubbish (i.e. confusing and nonsensical), but the auto-tune feature is not flawless and may require tweaking based on the requirements of your system. Here are the steps I used to tune my Sestos D1S PID to work with my Igloo Cooler RIMS Brewing System.
Step 1 – Choose the Temperature Sensor in Use
Press and hold the SET button. Release the SET button once the Sestos D1S PID shows HIAL. Press the SET button until you see Sn. This is known as the input setting and is where you specify the temperature sensor in use. Enter ’21’ if you’re using a PT100 sensor by pressing the up or down buttons, or enter ‘0’ if you are using a K-type sensor. After making your selection, simply wait until the screen shows the temperature being read on its display. If you have not done this correctly the Sestos D1S PID will flash orAL.
Step 2 – Set a Desired Temperature
This step needs to be completed with your brewing system filled with water, leak tested and pump in operation. The volume of water should be comparable to the amount of water you generally use whilst mashing. The water should be approximately 10c below your most commonly used mash temperature. I often mash in about 12 litres water at around 62c. As such, I heated 12 litres of water in a kettle and added it to the mash tun. Turn the pump on and start circulating the water through the RIMS tube and back into the mash tun at a flow rate of about 3 litres per minute.
Use the up or down arrow buttons to set the temperature required. As you are pressing up or down, the Set Value, or Sv display screen will change. This is the temperature in your mash tun that you want the RIMS tube to maintain. I made the set value 10c higher than the current water temperature. The decimal point in the Set Value will continue blinking until you have not made any changes for 10 seconds. Carry on to step 3 immediately after the decimal point stops blinking.
Step 3 – Run Auto-tune
Press and hold the SET button. Release the SET button once the Sestos D1S PID shows HIAL. Press the SET button until you get to CtrL. This setting specifies the control output, which is where you can switch the Sestos D1s between PID mode, auto-tune mode and manual mode. Using the up or down button, switch it to Auto. After Auto has been selected, wait until the Sestos D1S PID switches back to display the current temperature. The current temperature of the water exiting your rims tube will be shown on the Process Value, or Pv display screen.
The auto-tune feature will start to tune the system automatically. You will know that it is running because the unit will start flashing ‘AT’.
Whilst the system is auto tuning, the unit will bring the temperature up passed the Sv (see step 2) and then back down past the Sv. It will do this a number of times, and can take a while. It took my system about 30 minutes. Once the Sestos D1S PID ceases to flash ‘AT’ the unit has been tuned.
Step 4 – Test your PID
After auto-tuning has been completed, the Sestos D1S PID should be able to keep the Pv (the actual temperature of the water exiting your RIMS tube) within a degree or so of the Sv.
Step 5 – Problem Shooting
After completing Step 4, you may find that you Sestos D1S requires no further tuning. However, if your using a similar RIMS brewing setup to mine, you may have difficulties. My RIMS system uses a 3kW element on 240v, which, I believe, is over powered. This caused me two interrelated problems which, after the help of those on Jim’s Beer Kit, /r/homebrewing, Home Brew Talk and #homebrewtalk on IRC were easily solved.
Issue 1 – Boiling
When maintaining temperature the Sestos D1S PID will turn the heater on and off to keep the temperature as close as possible to the Sv. I didn’t experience any issues whilst maintaining temperature; however, the system started acting up when ramping temperatures (by 10c for example). Bubbles would start coming out the RIMS tube and the element would make a sound similar to that of a tea kettle coming to a boil. I was concerned that the water was extremely close to a boil, and that this would cause the wort to become scorched.
Issue 2 – Pump Cavitation
When ramping the temperature of the water, the water (wort) return line to the mash tun would shudder and shake. The water coming out of the return tube would also pulse. Here’s a short video of what this pulsing looks and sounds like: RIMS Tube Boil / Surge Video.
The Solution to Issues 1 and 2
Both of these problems were caused by the element being overpowered.
My system uses a 3kW element on 240v, which, when working at full capacity, was simply too much. It was boiling the water when ramping the temperature; the element was on for a long enough (read: seconds) for the water to come to a boil before the Sestos D1S PID noticed it was passed its Sv. The fact that the water as coming to a boil also caused a pressure change due the hot water expansion within the tube. If you have an overpowered element like I do, you need to do the following:
(1) Reduce the Control Period
The control period is the length of time that the Sestos D1S PID cycles on/off. I like to think of this as the length of time between which the Sestos D1S PID takes a new temperature “sample” to base its calculations on.
Press and hold SET until HIAL is displayed. Press set until Ctl is displayed. Use the down arrow to select 0 (nb – 0 = .5, 1 = 1 and so on). This makes the control period .5 seconds. This ensures that the Sestos D1S PID samples the water every .5 seconds to make the necessary calculations to determine power output.
Because the control period is every .5 seconds, it will take the Sestos D1S PID less samples (and hence less time) before taking a reading that tells the Sestos D1S PID that it is too hot in the tube.
(2) Reduce the Output Upper Limit
By changing the output upper limit you can limit the time during each cycle that the element can be on. For example, if you set the output upper limit to 10, and the control period to 0, the maximum time during which the element will be on is 10% of .5 seconds, or .05 seconds during each cycle. If we set the upper limit to 100, and the control period to 0, the maximum time the element will be on is .5 seconds during each .5 second cycle (i.e. 100% of the .5 second cycle time). Again, this dramatically reduces the time during which power will be running to the element.
To reduce the output upper limit, press and hold SET until HIAL is displayed. Press set until oPH is displayed. Reduce the oPH value accordingly. I had to change the oPH to 22 in order to solve my problems.
Using solutions (1) and (2) I made it so that my system no longer boiled, or surged during the ramping process.
If you have any questions, please leave a comment below!