Herms Controller Circuit Design - Some Advice/feedback

[squirt in the turns]

Hi folks,

I'm trying to figure out a layout for the HERMS controller I'm about to build, and I'd really appreciate any feedback you guys might have on the design below (especially if it's likely to kill me!). It's an all-electric set up, with a Crown urn (2400w) as the HLT, separate HERMS HEX (using element from a cheap kettle), and 2x2200w elements in the boil kettle. It'll be a 2-tier with the HLT on top, MLT and kettle on the same level below.

I'll be using a March pump to move wort/hot liquor around, and a 12v bilge pump to recirculate ice water through a plate chiller. While chilling, I also use the March pump to recirculate though the plate chiller and whirlpool.

For the 2 PIDs, I've got my eye on the cheap and cheerful Sestos D1S-VR-220 from evilbay. The whole thing will be plugged into 2 separate normal 240v domestic 10a circuits.

I thought about some kind of programmable embedded solution (Arduino or something) but have no experience with those. Maybe a project for later on.

I've tried to meet the following requirements:
1) It should be impossible to overload either of the circuits by having more than one high-wattage element drawing power from each one concurrently.
2) During the mash, it should be possible to power the HLT (to heat sparge water) and HEX elements simultaneously.
3) During the sparge it should be possible to simultaneously control sparge water temp with the HEX and be bringing the runnings up to the boil with one of the kettle elements.
4) When ramping up to the boil, both kettle elements should be on. PID #2 should switch off kettle element #2 (and maybe sound an alarm) just before 100c is reached.
5) When boiling, PID #2 should duty cycle kettle element #2 in order to maintain the boil (kettle element #1 is just plain on).
6) When cooling, PID #2 will shut off both the March pump and coolant pump when the pre-set yeast pitching temperature is reached.

Other notes: Not shown in the diagram are earth connections (obviously everything will be earthed), or the LEDs that will sit across various connections to indicate what is currently "hot".

I've taken a few cues from Wolfy's blog and The Electric Brewery, so credit where it's due. Also, apologies for my awful MS Visio skills (I wanted to attach the Visio file but AHB doesn't seem to allow it).

Thanks in advance!

 

[squirt in the turns]

Anyone? Come on, there's gotta be something wrong with it?!

 

[MastersBrewery]

looks good to me, but I think maybe with that level of complexity, the opinion of someone like Matho, or one of the other electronics gurus might hold a little more weight. And I'm home with some nasty bug so I may have missed something.

 

[gava]

I\'ve noticed within your diagram you\'re going to be using 240v DPDT switching and also switchin the neutral (blue) im not sparky but i\'ve built an eletric brewery and all my switching is done on the 12v side via SSR\'s and only switch the active \"brown\" the neutral goes directly to the outgoing 240v cable..

I\'ve just wired up a 12v control panel for a mate that has the same issue with only using 2 x 10amp plugs the way i stopped it using two at the same time was to have a simple switch that allows the switching on the SSRS... i.e. Kettle el #2 switch (on/off/auto) --> ket element2 SSR --> element .... on the other side of the switch HLT --> HLT SSR --> Element..

Not sure the best practice but I like the idea of being on the 12v side of switching when it comes to water...

this is a brewtroller diagram but you get the idea.. not sure if its the best but it works

https://picasaweb.google.com/lh/photo/N3vcT...feat=directlink

 

[Wolfy]

I'd not put much trust in my electrical setup skills because I'm sure there are many people more experienced and knowledgeable in this area.

If you are going to DIY, for an extra $20 or so, why not include 2x RCD/MCB (which also act as a switch) on the 240V inputs?
In addition, the Auber instructions say this: "When switching a North American 240V AC power, the heater will be live even when the SSR is off. Users should install a double pole mechanical switch to the power input." So I would be more comfortable installing a (or another) double pole switch before the PID/SSR/element because you might not always be pedantic about switching the existing DPDT switches back to '0' (The RCD might double for this purpose).

Unless you are going to also switch input from the temperature probes, it seems you'll need to move the position of the probe depending on the function at the time. (HEX then kettle, HLT then kettle). This also means that since the PID-control 'moves' between different 'systems' it will need to re-tune itself each time it's moved. In addition, when cooling, PID2 will 'throttle' power to the pumps so that the system gradually approaches yeast pitching temps, which IMHO is not what you want (just get it there as quickly as possible) so using the STC-1000 for this purpose is a better solution (see below).

(Sorry if I don't understand the setup or if this sounds opinionated)
But (unless it must run totally automated without you there to even watch it) I don't see any need to use the PID/SSR in the 2nd (bottom) circuit so I'd greatly simplify it:
Have the STC1000 control the HTL & 2nd element and turn the element on/off when the kettle reaches boiling.
Then when cooling, have the STC1000 turn both pumps off when pitching temp is reached (since you are recirculating your coolant anyway, I'd just run that continuously without digital control).

(More opinionated comments follow)
Personally I don't see the point in running a plate chiller in a recirculating chilling system. Either dump the cooled wort directly into the fermentor and (manually) control the the temperature by adjusting the hot/cold flow rates (which would also remove the need for digital-control for cooling purposes). IMHO this is the best way to run a plate chiller since it will 'fix' the volatile hop aromas due to 'instant' chill of the wort. OR if you want to use a recirculating cooling system, use an immersion chiller (with the coolant pumped through it and digitally controlled) which is not prone to blockage and cleaning issues like a plate chiller is.

 

[squirt in the turns]

I\'ve noticed within your diagram you\'re going to be using 240v DPDT switching and also switchin the neutral (blue) im not sparky but i\'ve built an eletric brewery and all my switching is done on the 12v side via SSR\'s and only switch the active \"brown\" the neutral goes directly to the outgoing 240v cable..

The use of DPDT switching was heavily inspired by Wolfy's circuit diagrams. The idea is to completely isolate the load from the supply when the elements are not in use. I might be misunderstanding your post, but it sounds like you're putting a switch on the +12v line between the PID and the SSR, and then another SPST switch on the live between the SSR and the load?

I\'ve just wired up a 12v control panel for a mate that has the same issue with only using 2 x 10amp plugs the way i stopped it using two at the same time was to have a simple switch that allows the switching on the SSRS... i.e. Kettle el #2 switch (on/off/auto) --> ket element2 SSR --> element .... on the other side of the switch HLT --> HLT SSR --> Element..

Not sure the best practice but I like the idea of being on the 12v side of switching when it comes to water...

this is a brewtroller diagram but you get the idea.. not sure if its the best but it works

https://picasaweb.google.com/lh/photo/N3vcT...feat=directlink

So is that switching done using a 3 position switch on a 12v circuit, between a single PID and 2 SSRs? I'm not sure I understand, sorry. Thanks for the link. The diagram is bit small/low resolution so it's hard to read the annotation and work out what everything does, but I'll check out the rest of that gallery too, and see what I can learn from that build.

 

[squirt in the turns]

I'd not put much trust in my electrical setup skills because I'm sure there are many people more experienced and knowledgeable in this area.

If you are going to DIY, for an extra $20 or so, why not include 2x RCD/MCB (which also act as a switch) on the 240V inputs?
In addition, the Auber instructions say this: "When switching a North American 240V AC power, the heater will be live even when the SSR is off. Users should install a double pole mechanical switch to the power input." So I would be more comfortable installing a (or another) double pole switch before the PID/SSR/element because you might not always be pedantic about switching the existing DPDT switches back to '0' (The RCD might double for this purpose).

Again borrowing from your design, my intention was always to include RCDs. I left them out of the diagram (along with earth connections, sensors, lights, etc) but forgot to mention this in the OP. I'd prefer not to have them double as switches, so will consider putting an extra "master" 240v DPDT switch on each supply. The reason I tweaked switch placement in comparison to your design is that I wanted the PIDs and STC-1000 to give temperature readouts even when the mains supply is switched away from their relays.

Unless you are going to also switch input from the temperature probes, it seems you'll need to move the position of the probe depending on the function at the time. (HEX then kettle, HLT then kettle). This also means that since the PID-control 'moves' between different 'systems' it will need to re-tune itself each time it's moved.

The PID that controls the HEX element is only ever used for that purpose, so should be no issues with it trying to tune itself to different uses.

The location of each sensor does not change throughout the process. The probes are only ever in the following locations:
STC-1000 probe - HLT
PID #1 probe - HEX coil output
PID #2 probe - Kettle

The brewing process would be:
1) Heat strike water: HLT element on (controlled by STC-1000), switch #2 in left position.
2) Mash recirculation: HLT element on - switch #2 in left position (heating sparge water); HEX element on (controlled by PID #1) - switch #1 in down position; March pump on - switch #4 in right position
3) Sparge: HLT on - switch #2 in left position, kettle element #1 on - switch #1 in up position (to heat runnings); March pump on - switch #4 in right position (pumping from MLT to kettle)
4) Ramping up to boil: Kettle element #1 on - switch #1 in up position; kettle element #2 controlled by PID #2 set to shut off just below boiling - switch #2 in right position, switch #3 in down position.
5) Boiling: Kettle element #1 on - switch #1 in up position; kettle element #2 controlled by PID #2 duty cycled to maintain boil level - switch #2 in right position, switch #3 in down position.
6) Towards end of boil, switch #4 is in right position, manually turning on march pump to sanitise pump and chiller.
7) Cooling: March pump and 12v pump controlled via PID #2 - switch #2 in right position, switch # 3 in up position, switch #4 in left position. Also, the unlabeled SPST switch for the 12v pump is closed.

If a switch is not explicitly mentioned in any step, it is off.

In addition, when cooling, PID2 will 'throttle' power to the pumps so that the system gradually approaches yeast pitching temps, which IMHO is not what you want (just get it there as quickly as possible) so using the STC-1000 for this purpose is a better solution (see below).

I wasn't aware of this . Or, I guess I kind of was, as I knew it would start trying to maintain the temperature, not just shut off, but didn't really think about the fact that it might start rapidly switching as it approaches the set temperature. Not sure what that'll do to the relay on the 12v circuit, the 12v pump and most importantly (expensively?) the March pump. But I'm sure it won't be good. Is there no way to change the function of those Sestos PIDs to make it work like a dumb STC-1000 in that circumstance? As you say, I could just swap the probe at that point and use the STC... would necessitate some changes to the circuit design though.

(Sorry if I don't understand the setup or if this sounds opinionated)
But (unless it must run totally automated without you there to even watch it) I don't see any need to use the PID/SSR in the 2nd (bottom) circuit so I'd greatly simplify it:
Have the STC1000 control the HTL & 2nd element and turn the element on/off when the kettle reaches boiling.
Then when cooling, have the STC1000 turn both pumps off when pitching temp is reached (since you are recirculating your coolant anyway, I'd just run that continuously without digital control).

Appreciate your input, so no worries. The main reason to include the 2nd PID is to be able to duty cycle the 2nd kettle element. I've been using my Crown urn (2400w) for ~20L batches and find it doesn't always boil vigorously enough. I figured 2x2200w elements would be the go, especially as I'm upgrading to a 70L pot to do double batches. I figured I'd never need less than the total output of 1 element, but probably the total output of 2 would be too much (especially for single batches).

It isn't intended to operate unattended, I just thought it'd be cool to have it shut off the cooling system when at the right temp.

(More opinionated comments follow)
Personally I don't see the point in running a plate chiller in a recirculating chilling system. Either dump the cooled wort directly into the fermentor and (manually) control the the temperature by adjusting the hot/cold flow rates (which would also remove the need for digital-control for cooling purposes). IMHO this is the best way to run a plate chiller since it will 'fix' the volatile hop aromas due to 'instant' chill of the wort. OR if you want to use a recirculating cooling system, use an immersion chiller (with the coolant pumped through it and digitally controlled) which is not prone to blockage and cleaning issues like a plate chiller is.

I already have the plate chiller and am experimenting with recirculating through it while whirlpooling (the first 2 batches made this way are still in primary, so we'll see). It does seem to get the temperature of the whole wort volume down quite quickly. Certainly the APA I made this way isn't lacking for hop aroma at this stage.

The objectives I've trying to achieve are:
1) Cool entire volume in the kettle as quickly as possible. Doing a single pass through the plate chiller, with time to whirlpool plus settle prior, the wort would be sitting for 30 mins or more after flameout, changing the hop profile. I realise that we're both basically citing the same reason for why using the chiller one way is better than the other... However, your point about "fixing" volatile oils is valid. I guess the argument for my method is that if the bulk of the volume is at the higher temperature for longer, that hop profile might be "fixed" at a different level to what it would have been if cooled immediately after flameout. I might make the same recipe twice, once with each method and see what it does to the late hops in each.

2) Leave cold break in the kettle.

3) Sanitse the chiller by recirculating boiling wort through it. Ok, this is a moot point as this could be done anyway even if doing a single pass. I am reasonably fastidious about chiller sanitation (I flush it with napisan, then I high pressure hose, then cover with foil and bake it after every use). However, this gives a little extra piece of mind.

4) Achieve precise control of pitching temperature.

I'll see if I can find a thread on AHB where someone did some maths relating to this. I think it was determined that a plate chiller would be more efficient than an immersion chiller even when used this way.

Thanks all for your posts, I've certainly got some stuff to think about!

 

[Wolfy]

Appreciate your input, so no worries. The main reason to include the 2nd PID is to be able to duty cycle the 2nd kettle element. I've been using my Crown urn (2400w) for ~20L batches and find it doesn't always boil vigorously enough. I figured 2x2200w elements would be the go, especially as I'm upgrading to a 70L pot to do double batches. I figured I'd never need less than the total output of 1 element, but probably the total output of 2 would be too much (especially for single batches).

It isn't intended to operate unattended, I just thought it'd be cool to have it shut off the cooling system when at the right temp.

Fair point about controlling the second element via the PID, but this could still be achieved using just the PID (circuit 1) and the STC1000 for HLT and cooling control (circuit 2). By direct wiring element 2 (always on) and running element 1 (switched with HEX after SSR1) through PID1 set to manual mode (as it should not be too hard to work out what % power cycle is required).

I already have the plate chiller and am experimenting with recirculating through it while whirlpooling (the first 2 batches made this way are still in primary, so we'll see). It does seem to get the temperature of the whole wort volume down quite quickly. Certainly the APA I made this way isn't lacking for hop aroma at this stage.

The objectives I've trying to achieve are:
1) Cool entire volume in the kettle as quickly as possible. Doing a single pass through the plate chiller, with time to whirlpool plus settle prior, the wort would be sitting for 30 mins or more after flameout, changing the hop profile. I realise that we're both basically citing the same reason for why using the chiller one way is better than the other... However, your point about "fixing" volatile oils is valid. I guess the argument for my method is that if the bulk of the volume is at the higher temperature for longer, that hop profile might be "fixed" at a different level to what it would have been if cooled immediately after flameout. I might make the same recipe twice, once with each method and see what it does to the late hops in each.

2) Leave cold break in the kettle.

If you've already got the plate chiller then buying an immersion chiller is probably not something you want to do.
However, I don't understand why you'd let the wort sit in the kettle for 30 mins, simply drain it at flame-out directly into the fermentor - of course that depends on how you filter and does leave the cold break in the fermentor - but is much simpler than having multiple pumps and digital controller for cooling.
I've had no problems getting the wort to the pitching temp I wanted by controlling the cooling/wort flow through the chiller, but our water here is likely colder than yours all year round.

 

[gava]

My switch are on the 12v side to the SSR... no switching is done on the 240 side..

on my mates rig since they dont have enough power to run everything at once I put in a SPDT (on/on) between the HLT and SSR and the Kettle Element#2 and its SSR.. this way even if the kettle element is switched on you have to turn the SPDT on for the kettle bit of a YOU CAN'T put both on at the same time... in the future this will be handled by software but at the moment its a manual option.. works well.

The use of DPDT switching was heavily inspired by Wolfy's circuit diagrams. The idea is to completely isolate the load from the supply when the elements are not in use. I might be misunderstanding your post, but it sounds like you're putting a switch on the +12v line between the PID and the SSR, and then another SPST switch on the live between the SSR and the load?



So is that switching done using a 3 position switch on a 12v circuit, between a single PID and 2 SSRs? I'm not sure I understand, sorry. Thanks for the link. The diagram is bit small/low resolution so it's hard to read the annotation and work out what everything does, but I'll check out the rest of that gallery too, and see what I can learn from that build.

switching is done to a single SSR (for each element/pump/electric ballvalve) but from two sources i.e. brewtroller/arduino/pid the other completes the circuit and manually turns the SSR on. pretty much what all rigs do..

 

[squirt in the turns]

Cheers gava, I think I understand your design paradigm now. Can I ask why you don't like switching 240v? I understand that SSRs are in an "always conducting" state even when open, so with fixed wiring between the SSRs and their loads, the load is technically always "hot"? I'm sure that this isn't a problem, but using DPDT switches like Wolfy does it, the elements are completely isolated when not in use, which seems safer to me.

 

[gava]

Reason why I dont like switchin on 240v comes from back in the day of computer cases that had a 240v switch on the front, I've been zapped twice and once it "welded" the switch to the case.. Now I tend to keep them apart.. I recently seperated my 240v and 12v so now my control unit is only 12v which is near the brewery and the 240v is (will be) mounted on the wall in a water tight unit.

240v sitting in the corner ready for new face plate and mounting.

12v only box near the brewery

 

[squirt in the turns]

Fair point about controlling the second element via the PID, but this could still be achieved using just the PID (circuit 1) and the STC1000 for HLT and cooling control (circuit 2). By direct wiring element 2 (always on) and running element 1 (switched with HEX after SSR1) through PID1 set to manual mode (as it should not be too hard to work out what % power cycle is required).

I thought about just using 1 PID, but before I had any replies to my OP, I went ahead and bought 2 (plus the STC-1000) . They're pretty cheap at $40 each. I liked the idea of having an Electric Brewery style control panel with each vessel linked to its own temperature control/reporting device, with everything nicely labelled. Having to switch the STC-1000 to measure and control the kettle instead of the HLT will throw this out.

However, I still have hope that I can use the PID to control the process without it "throttling" or rapidly switching (which will surely frak my pumps). If nothing else, before starting cooling, I can set the "control period" to a nice large value like 30 seconds which should prevent any damage. Any overshoot caused by this 30 second cycle when cooling won't matter (or could be accounted for when programming the SV). This is assuming the "control period" setting applies to its PID output and not just the duty-cycle mode (which I believe it does). Anyway, I'll have a play around when they arrive and post my findings.

And, as you mentioned earlier, Wolfy, using the same PID for the HEX, and then heating and cooling in the kettle, might throw out its tuning. 2 PIDs avoids that.

If you've already got the plate chiller then buying an immersion chiller is probably not something you want to do.
However, I don't understand why you'd let the wort sit in the kettle for 30 mins, simply drain it at flame-out directly into the fermentor - of course that depends on how you filter and does leave the cold break in the fermentor - but is much simpler than having multiple pumps and digital controller for cooling.
I've had no problems getting the wort to the pitching temp I wanted by controlling the cooling/wort flow through the chiller, but our water here is likely colder than yours all year round.

Yep, got my chilling solution, not feeling inclined to spend any more on it - this caper is going to cost enough as it is. With water temperatures here, even for ales, at least some portion of the cooling process has to use ice water (and this is in winter). Recirculating coolant is, for me, less hassle than a pre-chiller, and I think uses less water overall (although there's electricity required to make ice, so... ). I think I'm getting good results recirculating both wort and coolant so far, just want a bit more control.

This is thread I was referring to before: http://www.aussiehomebrewer.com/forum/inde...showtopic=62203
Other AHB'ers are doing it, see?

Re: letting wort sit:
I thought the standard process was: flameout -> wait for convection currents to cease (optional?): 5-10 mins?? -> whirlpool (use a spoon, or a pump if you're cool B) ): 5-10 mins? (2 mins for me when I was using a spoon-what a PITA!) -> Wait for whirlpool to settle all the trub in the middle of the kettle: another 5-10 mins?

When chilling in the kettle, either immersion or plate chiller recirculation, the temp of the entire wort should get under the isomerisation threshold pretty quickly and then lock in aroma volatiles.

I don't filter between the kettle and fermenter. It sounds like maybe you do, Wolfy? Is this to catch hot break/hops? Can you filter in line, post-chill and catch cold break?

 

[Wolfy]

And, as you mentioned earlier, Wolfy, using the same PID for the HEX, and then heating and cooling in the kettle, might throw out its tuning. 2 PIDs avoids that.

Hence why I'd run it in manual-mode for controlling the kettle, but only one PID would not give you the digital display for each vessel. I was thinking more about the complexity of wiring and setup than the cost of the controller.

Re: letting wort sit:
I thought the standard process was: flameout -> wait for convection currents to cease (optional?): 5-10 mins?? -> whirlpool (use a spoon, or a pump if you're cool B) ): 5-10 mins? (2 mins for me when I was using a spoon-what a PITA!) -> Wait for whirlpool to settle all the trub in the middle of the kettle: another 5-10 mins?

It might be popular but I don't think it's standard, it is a process endorsed and publicised by Jamil Zainasheff so it gets a lot of publicity. But not all filtering systems require a whirlpool to create a cone of trub and not all cooling systems require wort recirculation, it just depends on how the system is setup.