Mash Temp Control

[LandoLando]

Hi, this is my second post. The first post was apparently in the wrong sub forum. I've been brewing for about 5 years now. I'm a process engineer so it follows that I am curse with an insatiable desire for process control.

I have a 14 gallon kettle with a valve on the bottom. I also have a 10000 BTU/hr heating element from a hot tub. I want to install the heating element inline with a Brau inline pump and control the temp with a thermistor, 50A solid state relay, and Arduino microcontroller. The plan is to bring the mash water within 5 F of mash temp with my burner, and then run the pump and heater to control the temp. Add the grain once the mash water is at the appropriate temp and let her rip.

Any concerns?

Are the Bräu pumps quality?

If i have a constant whirlpool can i trust that the temp is uniform throughout the mash?

Any one do multiple step infusions with a similar setup?

 

[BrunDog]

Sounds very reasonable. 10k BTU/hr is about 3kW, so that's plenty of power to do a step mash. I am not familiar with the Brau but it should work fine. It's plastic, low power, and inexpensive, so don't expect Chugger/March performance, but many here are using similar pumps successfully. With your Arduino control, you can also use PWM to control their flow rate. I assume you will write a PID algorithm to perform the heating. I suggest you build in a safety to make sure the power is cut to the heater if flow ceases.

Edit: yes, the whole point of recirculation is to maintain consistent temps throughout the mash volume.

 

[LandoLando]

Sounds very reasonable. 10k BTU/hr is about 3kW, so that's plenty of power to do a step mash. I am not familiar with the Brau but it should work fine. It's plastic, low power, and inexpensive, so don't expect Chugger/March performance, but many here are using similar pumps successfully. With your Arduino control, you can also use PWM to control their flow rate. I assume you will write a PID algorithm to perform the heating. I suggest you build in a safety to make sure the power is cut to the heater if flow ceases.

Edit: yes, the whole point of recirculation is to maintain consistent temps throughout the mash volume.

I planned to go simpler than that. The orginal plan was to run the pump continuously (plugged directly into 110VAC) and then just on off control for the heat with an SSR, and yes I plan to wire a load resistor on the pump circuit so I can prevent the element from heating with out flow.

I just have the SSR lying around and you can't really control an SSR with PWM so PID would be impossible without a VFD or signal generator.

 

[LandoLando]

Here's my design:



A brewer friend said I may need a bleed on the top to keep the wort from boiling and scorching. Is that necessary?

 

[doug293cz]

Here's my design:



A brewer friend said I may need a bleed on the top to keep the wort from boiling and scorching. Is that necessary?

You need to make sure that any heated portion of your element can never be in an air bubble. Your design will have an air bubble at the top of the RIMS tube. So, depending on the heated length of the element, you may need a bleed valve. Another option is to have the element enter from the bottom of the RIMS tube, and then you don't have to worry about the bubble at the top. The bottom element entry also allows you to insert a temperature probe thru the top of the RIMS tube. For a RIMS you want the controlling temp probe as close to the end of the element, on the flow exit end, as you can get it.

Brew on

 

[LandoLando]

You need to make sure that any heated portion of your element can never be in an air bubble. Your design will have an air bubble at the top of the RIMS tube. So, depending on the heated length of the element, you may need a bleed valve. Another option is to have the element enter from the bottom of the RIMS tube, and then you don't have to worry about the bubble at the top. The bottom element entry also allows you to insert a temperature probe thru the top of the RIMS tube. For a RIMS you want the controlling temp probe as close to the end of the element, on the flow exit end, as you can get it.

Brew on

Cheers. I thought of putting the element on the bottom shortly after I posted this. My plan is to clock the pump 90 degrees from where it is in the screen shot above and put another tee in at the bottom for the heater and put the thermistor on the tee on the top.