Advice please: 1 PID control panel critique

I was going to build a HERMs system using my propane burners, but decided to go ahead and upgrade to an electric system. I've read over Kal's site, and looked at a few of the systems on this site for some inspiration.

My panel design was built with affordability in mind, hence the one PID. The idea is that the three position switch at the bottom would determine which kettle the PID would be interacting with.

When the switch is on the HLT, the PID will control the heating element, and get feedback from the temperature probe inside of the HLT.

When the switch is on the Mash Tun, the PID will be getting feedback from the temperature probe on the output of the Mash Tun.

When the switch is on the Boil Kettle, the PID will control the heating element, and perhaps be getting feedback from the temperature probe inside of the Boil Kettle.

I notice that most people use the three position switch for only two uses, and have the middle section used to separate the two. I'm hoping that by using the middle space as the Mash Tun, and thus not controlling anything, I will still be OK.

Also, do I need a button to reset the alarm, or can this be done at the PID?

I decided to skip the emergency off button as well. Instead I'll just use the main power key if needed.

So is this workable? Is there anything I need to change?

If you turn off your main power, do you lose power to the pumps too? What do you turn the switch to when you're done with your boil and you are running one of the pumps to chill?

The switch could be put on the mash tun, as it would not control any heating element. Although, I wouldn't be opposed to an On/Off for the PID if it's needed.

I've always heard you're going to get temperature variances switching between probes like that. Each one will have a couple degree offset you'll have to program into the PID. There are certainly ways around going to a more expensive build, however.

With HERMS you wouldn't really need to put a probe in your mash tun if you're doing a constant recirculation, right? I know on Kal's build whatever temperature he sets the HLT PID at, the mash stays within half a degree or something. As long as you have a trusty hand-held thermometer you could do that with ease. I have a constantly-recirculating electric direct-fired RIMS, a Brutus 20, and as long as I keep the flow open my temperature between the HLT (bk in my scenario) and the MT is 1 degree.

Or, you could go to a two-PID system and keep the mash probe/pid setup constant, then have the HLT PID calculated to the HLT probe, and just switch that PID to the boil where you don't need an accurate temperature.

As for the alarm, the PIDs can turn off the alarm by changing the parameters, that's it. So if you have your alarm set to notify you when your strike water hits 160, the only way to turn it off is to raise the alarm to alert at 165 or whatever. That's where a simple toggle on-off switch is very handy.

I guess I only need one temperature probe, and I can just take a manual temp to ensure the mash is at the right temp. that would eliminate the middle toggle on the switch.

Just make sure that won't be something you regret. Adding another PID isn't too terribly expensive in the long run.

I think I'll be OK with the one PID, and I'll be able to upgrade later if needed.

I have a limited budget right now as the wife has been laid off so I'm trying to save wherever I can.

Will I run into any problems making my control panel out of wood? I was going to build my stand from wood, and was going to incorporate the control panel right into the stand. I just don't know if things will get too hot.

A thought regarding your instrument layout, if you plan on being able to upgrade to a second PID, make sure your panel layout is such to support that. Otherwise you might be looking at have to create some kind of an overlay to get the spacing for the PIDs correctly.

The panel is just going to be a wooden face on a 45 degree angle with hinges. So when I'm ready to upgrade, I'll just cut out a new face for the panel.

I noticed that some people have 220v lights and 110v lights. Are the 220v just for the main power, and the 110v for the other accessories?
Also, do the switches simply need to be 110v or do they need to be 220v?
Is it safe to assume that the Key Switch will need to be 220v?

I don't recall you stating the voltages you plan on using. The answer depends on what your plans are. I have both 110v and 220v lights in my panel. The 110v lights are integrated into the switches for my pumps, contactors, and the main PID power button. The 220v lights are pilot lights for the elements to let me know when power is flowing to them, or more accurately, when an outlet is hot.

I plan on using two 5500w 240v elements, and then the reguard 110v march pump. The PID will be auber.

Sounds good! Similar to other designs here. A HERMS setup with elements in the BK and HLT. RTD probe in the HLT. Pump to recirc wort from MLT to HLT. Pump to BK when conversion is complete. Boil. Recirc hot wort through HERMS again - this time with with ice water or immersion chiller or CFC.

Should be a nice system. This thread contains one of P-J's schematics that should work for your build.

Since I'm not going to use the 1 PID w/ three different temp probes, then I assume that I won't need a PID off switch, as the middle position would be used for that.

lunchbox said:

Since I'm not going to use the 1 PID w/ three different temp probes, then I assume that I won't need a PID off switch, as the middle position would be used for that.

Click to expand...

Yes, if you use the switch to determine which element gets power, then I think the middle position of the switch would effectively be "OFF" where no element receives power.

On my rig that stlbeer linked to a few posts up, my element selector switch is a dual pole dual throw On-Off-On switch. There is a 110 volt current that runs through it. When it's flipped to the left it triggers a contactor that allows 220 to flow to the HLT element (the PID uses the temp sensor in the HLT to maintain water temps). In the center position it's off so no power goes to either element. When it's flipped to the right it triggers a different contactor that allows 220 to flow to the BK, and the Auber PID is run in manual mode to allow a % of power to go to the element to control the boil rate. I have a dial thermometer mounted on my MLT to see the mash temp.
You can build a similar system without the contactors, but you'd need an element selector switch rated for 220v and 25-30 amps. I chose not to go that route because I didn't feel comfortable touching a switch with wet hands that had 220v 25 amps going thru it, so I opted for contactors to control the load. Contactors are fairly cheap, and when you consider the additional cost of the higher amp switch, there's not a big cost difference. Auber has contactors too, for like $15.

So the guts of my rig has 1 temp probe, 1 pid, 1 SSR and heat sink, 1 selector switch, 2 contactors, and 3 power toggles for the PID and 2 pumps (plus e-stop and a couple lamps). The PID power switch is not entirely necessary, but I just wanted to be able to shut off the PID if I wanted to. The whole system wasn't that expensive to build. I've recently added a PWM circuit to control the boil kettle, but you can ignore that and look at the original diagram for your rig.

BTW - I'm brewing Saturday, so you can swing by to see it in action if you get up early. It's bloody hot out so I'm getting an early start.

After much discussion with lunchbox I believe a plan has been put together.

The finished panel will look something like this:



The Main Power switch will be a key lock switch. (I could not find an image of one to show in this planned panel display)

The Red 'off' indicator light required some special wiring so that it would light when neither the HLT or BOIL element are selected.

The wiring plan will be this:

And - as always - Click on the image to see a full scale diagram that is printable on Tabloid paper (11" x 17")



Things certainly can change as this is a work in progress after all.

Wishing you great success.

P-J

stlbeer said:

Yes, if you use the switch to determine which element gets power, then I think the middle position of the switch would effectively be "OFF" where no element receives power.

Click to expand...

Thank you for that. Your observation helped me with the plan on how to implement 'stuff' for this layout.

P-J