PID-controlled Mash Tun

Hi everyone,

I'm working on an electric brewery build out and plan to largely base it off of a design that my good friend bigljd created several years back (https://www.homebrewtalk.com/f170/my-two-5500-watt-element-1-pid-ssr-build-281085/). The main difference is that in addition to regulating the HLT team with a PID/SSR relay, I want to also be able to measure the temperature in my mash tun with a second probe, and toggle a pump which transfers wort through a coil running through my HLT. Depending on the measured mash tun temp, the pump would turn on or off to maintain a steady temp. The water in the HLT would always stay the same temp and be maintained by a separate temp probe/heating element setup.

So my main question... how do I go about doing this from a component and wiring standpoint? Thanks to bigljd, I know that I can toggle the heating element with an SSR relay connected to my PID. Can I do the same with my pump or do I need a different type of electrical component? I'm good at following instructions and wiring things up based on someone else's directions, but don't have the electrical background or knowledge to know which parts to use or design my own schema.

The primary parts I was planning to use for the Mash Tun temp regulation are as follows:

1/16 DIN PID Temperature Controller (SSR control output)
http://www.auberins.com/index.php?main_page=product_info&products_id=3

40A SSR
http://www.auberins.com/index.php?main_page=product_info&products_id=30

Heat Sink for Solid State Relay, 40A (I assume I need this because I need it for the other one based on bigljd's diagram for the HLT PID)
http://www.auberins.com/index.php?main_page=product_info&products_id=77

I'm about to pull the trigger on my final order from auberins but wanted to get some help beforehand so I don't have to send anything back or place another order. Thanks so much for anyone that can help!

Lots of views but no love yet. Can anyone help me out?

Thanks in advance!

Most people use a slightly different approach to controlling Temps in the mash tun. Instead of turning the pump on and off we run the pump the entire time and turn the heating element on and off.

What you are proposing will require a second temp controller and SSR or relay to control the pump. I don't see any advantage to doing it the way you are proposing.

Thanks crane, I did consider that approach as well but wasn't sure how quickly the HLT water would cool to where it needed to be with a still hot/warm element inside it, and wondered if it might cause for a higher mash in some cases.

Also, with this setup, do you heat your HLT element for the initial strike water based on a temp probe in the HLT, and then switch the heat for the element to be based on the mash tun temp probe? Not sure if that is even possible, but that would give you control over the same element with two different probes/stages of brewing.

Hi Denny,
When you first mentioned this idea I thought you wanted to eliminate the probe in the HLT and just monitor MLT temps - this wouldn't work well since you couldn't heat strike/sparge water accurately in the HLT. But, adding a second PID/SSR/probe for the MLT would allow you turn a pump on to circulate the wort thru the HERMS if it cooled below the target temp. In theory it would work - I'd be interested to see it work in practice. The MLT probe would have to be fairly low in the MLT to accommodate smaller grain bills - and since heat rises I'm wondering if you have a lot of pump 'false starts' as it kicks on, pulls warmer wort from above across the probe, causing it to shut off when it quickly hits the target temp. Not sure if that would happen, just thinking out loud.
Like crane mentioned, I think most brewers just re-circulate the thru most of the mash. It gives you nice clear wort at the end of the mash, and if you have your HLT PID dialed in it should hold a pretty steady temp. I know you mentioned Paul had issues holding the mash temp steady- how well was his PID doing at maintaining water temps in his HLT? Has he run auto-tune on the PID? If the PID is not holding a steady temp (within 1 degree of the target), then the HERMS won't work right either. Also, re-circulating the water in the HLT is important for proper heat transfer in the HERMS coil - I don't know if Paul has any recirculation in the HLT. Hope this helps.

LD

edit/addition: I think most people are using the probe in the HLT to control temps - I haven't seen a setup that uses a MLT probe to control the HLT element. If you switched over to a MLT probe that would trigger 2 SSRs when the temp drops below the PID target temp, the PID could turn on the element and the pump and keep them on until the MLT temp was reached, then shut off the element and the pump. I'm not sure what effect this would have on the HLT water temps. It seems like you could end up with some really high HLT water temps, and possibly be denaturing enzymes in the wort as they went thru the HERMS coil. Not sure on that one.

Thanks LD, I think I will keep it simple for now then and go with the HLT probe and 1 PID/SSR relay. I can always add another one down the road if I want to.

I was actually considering a second PID for the mash temp also this way I could set a higher HLT temp to allow temp changes in the MLT to happen faster. I was planning to use a pair of motorized ball valves to direct the wort through the HEX when heat is needed and thru a bypass when it's not this way the pump isn't cycling. I should also get the nice clean wort from a continuously circulating system not to mention a more uniform mash temp from the continuous circulation.

I had concerns about denaturing enzymes too but it was pointed out that denaturing is not an instant reaction and RIMS systems don't seem to have to much trouble with it. I was thinking an HLT temp of 180F to get me all the way to mash out.

I'm with you though in thinking it's getting a bit complicated so my Phase I is HLT monitoring and heat control. Mash temp will be a later phase of the project.

Denny,

I have a very similar setup currently; if you're doing a true PID mode with a single PID controller controlling two different vessels and two different processes you should really have two different PID controllers or you're going to confuse the "fuzzy logic". -The Pid will try to learn the characteristics of your vessel and what you're using it for and by switching the PID controller between two probes in two different vessels it ill get confused and start behaving strangely and you will need to constantly recalibrate it.

If one vessel is going to be in PID mode and another in %output manual mode, you're fine; but two vessels in PID mode will confuse it.


Adam