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Topic: Regulate cooling water temp on a still (Read 1 time) previous topic - next topic


Hi, I'm currently manually adjusting a water flow valve to regulate/maintain the cooling water temperature on a still (for making alcohol).
I want this to be automated using Arduino as it's a five hour process and I think it will be fun.

I need someone who would be willing to figure out a parts list for me to buy and to program the code required to run the program. Or someone who can point me in the right code direction. Arduino is something I'm definitely keen on getting immersed into, I think this would be an easy project for that someone who can help and a great "chucked in the deep end" project for me. I'm really good with electronics and have made many projects, it's the code and the how that I'm not familiar with.

Ok so the still requires cooling water to pass through the condenser coil to condense the alcohol. The temperature range that this cooling water needs to stay in is, no less than 50°C and no more than 65°C. At the moment I turn a pin valve to increase or decrease water flow to raise and lower the temperature. The water is pumped from a basic pond pump at a rate of about 400-500mlh. So it's not high pressure or large volumes of water. The piping is about 1/8 inch clear flexible hose.
My thoughts are either the pump can be the variable (Increase or decrease the speed of a water pump) to regulate flow. OR, a water control valve with a servo? The adjustments I make manually on the pin valve to change the flow are really minor and it doesn't seem like much change in 'water flow' although the temperature will move 2-3°C with this small adjustment.
I'm not standing there the whole time either, once it gets up and running I can leave it for hrs before I need to make adjustments, it can fluctuate between 51-55° on its own and isn't a problem. I do monitor it with a baby monitor and have even done a FaceTime call to monitor the temp! Hehe

I can take some pics of the setup as is (not sure if that helps) I can also take a video of it working and me adjusting the temperature with the pin valve. :)

Thanks in advance


You can probably get by with an off the shelf temperature controller like this one from Inkbird  and have it drive a solenoid operated valve like this one Using off the shelf parts may be a simpler and proven path to temperature control of the still so you can sit back and enjoy the fruits of your labor, in moderation of course.

Hope this helps,


Does the alcohol condenses on outside of the coil (coolant in) or  inside (coolant out)?

If the second, it's somewhat easier to measure temperature outside the coil and have the thermostat just  turn on/off the pump.

If the coolant is inside the coil there is much less thermal inertia, so the thermostat's relay will switch a lot more frequently.


Nov 15, 2019, 12:35 am Last Edit: Nov 15, 2019, 12:36 am by cattledog
Can you provide more information about the pump. Is it an AC or DC motor? Also more information on the needle valve would be useful. Is it multi turn?

The temperature range that this cooling water needs to stay in is, no less than 50°C and no more than 65°C.
How is the temperature measured?  It appears there is a display which you read to adjust the flow, but we will need more information about the temperature measurement in order to figure out how to get it to the Arduino which will control the valve or pump.

Is the cooling water heated by something other than the hot vapor in the condensor? Or What keeps it between 50C and 65C?

Your project is very doable, and a Google search on "Arduino home still" brings up many links.


Nov 15, 2019, 02:12 pm Last Edit: Nov 15, 2019, 02:16 pm by Danfiel
Hey guys thanks for the input! And apologies for some missing essential info!

Firstly the cooling water comes from the main water supply, so its cool. Then its pumped from a pond   PUMP to the pin valve.
I have a feeling that the pond pump is AC and non adjustable, i'm more than happy to get a good DC water pump that is adjustable by changing the voltage.

The pin VALVE simply restricts the flow of water by turning the knob.

The cool 'Tap' water then travels through a hose and attaches to the condenser coil on the outside of the still, the water then travels internally (Cooling/condensing the alcohol) and in turn, the cooling water becomes hot and exits via another pipe (I then direct that hot water into the pool). At the point where the hot water comes out a digital thermometer has its probe mounted and submersed in the hot water. This is the only temperature reading I use to maintain the temp between 50-65C.

The links dont work.....



Sorry guys :(


Thanks for more information. I think you will be able to work through this. Reading a temperature and then controlling a pump or valve is well suited for an Arduino. At some point in the future if you think you can do this by yourself and have some details worked out, you may want to move to the main board instead of "Gigs and Collaborations".

The water is pumped from a basic pond pump at a rate of about 400-500mlh.
The specs on the pump(15w=1000l or 40w=2500l) don't appear to be consistent with this earlier statement. Which pump model do you have?

Can you determine the outlet flow rate at steady state through the needle valve by collecting the output in a bucket?

If you are going to control the pump, you will need a DC pump. Sizing it for the flow will be important. How far away from the still is the pump and water source? I think the layout is relevant as to whether or not you want to control the pump or the valve. Do you have a budget in mind for the hardware modifications. Do you have any leads on a motor controlled valve from the home brew store you work with?

The link on the thermometer and display did not come through. Can you please try again. This is important to determine if you want to use the present probe/sensor or if you want to change to something like a DS18B20 to use with an Arduino.

Do you currently have an Arduino? Do you have any experience with computer coding?


Nov 15, 2019, 10:15 pm Last Edit: Nov 15, 2019, 10:46 pm by blimpyway Reason: PS
I'm not sure but an adjustable valve could be more expensive & complicated.. my feeling is cheaper and simpler to use a 12V DC bilge pump with a half bridge driver (even an L298N module might work) for PWM control.  And a temperature sensor like the aforementioned DS18B20. It is cheap enough not to worth trying to connect to the existing digital thermometer. You can keep it as control.    

here-s just an example of such a pump which might have the right flow capacity.

The specs on the pump(15w=1000l or 40w=2500l) don't appear to be consistent with this earlier statement.
Yeah, that's a question. First I thought he meant 400-500l/h but If the hose is only 1/8 inch (3mm),  diameter and the flow is still restricted by the valve , the pump should be quite choked.


Nov 16, 2019, 12:51 am Last Edit: Nov 16, 2019, 12:57 am by Danfiel
Thanks, try this link:

I'm more than happy to purchase an Arduino temp module. I'm hoping this can come in around $50-80 AUS for parts and  similar for someone to write the code and help. I have little experience with code but it's definitely not beyond me, I'm going to get a UNO kit today and start a few projects.

The pump will be choked up for sure, I needed to get one with the highest head lift otherwise it just doesn't push the water up through the still. The pump sits on a bench right next to the still and before everything heats up I do indeed measure the flow rate with a bucket, the recommended flow rate from manufacturers is 400-500ml per minute, I said per hour before sorry bout that! I measure this from the outlet hose of the still.
That's not me... But that exactly the same setup. The only difference is I pump the water through.
Appreciate it guys


Nov 16, 2019, 05:45 am Last Edit: Nov 16, 2019, 05:48 am by cattledog
I'm going to get a UNO kit today and start a few projects.
Great way to get started. I would also purchase a DS18B20 temperature sensor packaged in the metal sleeve. I looks like it will fit into the well where the current sensor is. Its quite possible that the existing sensor is indeed a DS18B20.

You should also get a basic 2x16 lcd character display if one does not come with the kit. One with the i2c backpack attached will require less connections to the UNO and will be more simple to connect.

Reading and displaying temperature is a place to start. There are plenty of tutorials about using a DS18B20.

I think that proceeding with flow control from the pump speed instead of with an automated throttling valve is likely the least expensive way to go. With the needle valve removed(or screwed all the way open), you will likely not have the issue of pushing the water through the still. It looks like the elevation pump head height is less than 3 meters. The internal flow resistance in the condenser obviously adds more.  The more definition you can get on flow rate and head height will help you select a pump. You want to get the pump sized correctly, because if its oversized and you need to run it at a slow rate, you may loose some head height capability.


Your AC pump may respond well to phase cutting - like a light dimmer does to dim incandescent lights. That does mean you're playing with high voltage, with all its safety implications.

I'm not sure but an adjustable valve could be more expensive & complicated.. my feeling is cheaper and simpler to use a 12V DC bilge pump with a half bridge driver (even an L298N module might work) for PWM control.
Many 12V pumps are brushless, and for that reason can not be controlled by PWM.
If it's a brushed DC motor it can be controlled, but no need for the old, lossy L298N (which is pretty much obsolete anyway). A simple MOSFET will work much better and is much easier to set up and control.

When controlling the thing, allow for sufficient delay in setting the motor based on the temperature, as the water is pumped in from one side and you'll be measuring the temperature on the other side. When increasing the flow it takes while for the cooler water to reach the thermometer...
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