PIDs, Probes & SSRs:

[biertourist]

No. I have a PID for my BK. Temp probe is direct through the kettle wall. The PID will be set to just below boiling point, when target temp is hit - say 98c, an alarm will sound letting me know it's close to boil. You then set the temp point a degree or two above 100c, set to manual - most people use about 80%, meaning the element fires 80% of the time - this maintains a rolling boiling. This is for a setup with a 5500 watt element. This process ensures I can walk away and do something else and not face a boil over. When the boil is finished, I can set the temp point to pitching temp, recirculate through counterflow chiller and back to the BK - alarm will sound when pitching temp is reached. It's not much more of complication when already adding a few other PIDs, and it most definitely can have a purpose in your brewing process.

Honestly, objectively look at just how long and complicated your description is (and it is simplified vs. what you actually have to do; you have to hold down buttons every time you switch between auto and manual mode, then hold other buttons to change the % output or temp, remember which buttons to push when, then wait for the timeout value so the PID actually starts doing what you just told it  to do, etc...).  You have a $60 piece of equipment that can do integral and differential calculus in a boil kettle that just needs "more heat" or "less heat".


Same process with a PWM dial controlling an SSR:
Leave dial set on "high" (like an oven knob) until wort boils, then dial it down to reduce the volcanic boiling (it instantly goes down) -if you need more heat dial it up a bit more; if less, down a bit more.

Keep It Simple. (Or waste your life fidgeting with your brewery hardware instead of making beer.)


With PWM:

• You don't have to recalibrate PID controllers so they accurately read heat
• You don't have to worry about temperature probes including cleaning, them breaking, resoldering cords, etc..
• You don't have to worry about which buttons to push when to change temp or switch between modes; or which esoteric setting you need to modify when it refuses to switch between automatic and manual modes (yes, that's a thing; yes, it's annoying)
• You don't have to hold a button for 3 seconds to enable a mode that enables you to drop the temperature while hot break is spewing everywhere making a huge mess of your brewing area
• You don't have to spend 60 quid and precious space in your control panel when a simple 2 quid pwm dial will work

I've bought a lot of "high-end" brewing equipment in the last year and a number of those items made brewing harder, not easier.  IMO, a PID controller, rtd style connector temp probes, tri clamp fittings, a plate chiller, and a shiny flat-bottomed boil kettle are all in that category. -They're "cool", but they introduce more problems than they solve.

I'm now moving to v2.0 of my stainless "dream system" and my upgrades include PWM dial-controlled boil (vs pid), removing triclamps and swapping them out for quick disconnects (camlock style in my case), counter flow chiller, and a keggle-based whirlpool kettle.  I used to think that these were "downgrades", but they're not; they work better and require less effort to use and less maintenance, so they're upgrades.


My 2 bucket brewery in Dublin (Mashtun: insulated bucket with mesh screen attached to a ball valve; Boil+HLT: plastic bucket with 2 Charlie Shiels kettle elements / computer power cords) was the single easiest-to-use brewery I'll probably ever own... I'm afraid it's all downhill from there, no matter how much money I spend and how many tweaks I make. (although I transferred WAY too much trub to my fermenter with that brewery and always had burny fusols because of it.)



Adam

[biertourist]

No. SSR fail in the closed state. This means that the circuit is closed, which allows electricity to run though it. This is why a mechanical contactor and on/off switch is required before the SSR so that you can turn of the electricity to the element. The on/off switch allows electricity to run to the contactor which energizes the coil, placing it in a closed state, meaning electricity can now flow through to the SSR and down to the element, the PID turns the SSR on and off depending on the temperature setting etc. 

SOMETIMES SSRs fail in the closed state.  -When they burn out due to overheating that's true, when they burn out from going from room temperature to being very hot, back to room temperature again and internal solder joints fail, they fail open.  My first SSR straight from Ebay arrived broken in a "fail open" state. (This is why all of the electrical brewery schematics on HomeBrewTalk made by PJ have contactors or physical switches to cut off the current.)


"
Q  What is the normal failure mode of SSRs and why?

A   There are 2 failure modes; failed in the open state and failed in the closed state.  Closed failures are the more common failure mode and this form of failure most often occurs due to overheating of the SSR which leads to an internal melting of components which end up as a closed circuit.  The open failure is most often caused by a separation of solder joints due to extreme temperature changes over the life of the SSR.
"
http://www.hbcontrols.com/ssr-controller-assemblies-technical.asp


Adam

[armedcor]

I'm glad this has popped up. I'm just starting to research PIDs. I'd love to build a controller for my HLT and run my 2.75kw element and a pump off it. Any real basic guides banging around?

[Ozbrewer]

No. SSR fail in the closed state. This means that the circuit is closed, which allows electricity to run though it. This is why a mechanical contactor and on/off switch is required before the SSR so that you can turn of the electricity to the element. The on/off switch allows electricity to run to the contactor which energizes the coil, placing it in a closed state, meaning electricity can now flow through to the SSR and down to the element, the PID turns the SSR on and off depending on the temperature setting etc. 

SOMETIMES SSRs fail in the closed state.  -When they burn out due to overheating that's true, when they burn out from going from room temperature to being very hot, back to room temperature again and internal solder joints fail, they fail open.  My first SSR straight from Ebay arrived broken in a "fail open" state. (This is why all of the electrical brewery schematics on HomeBrewTalk made by PJ have contactors or physical switches to cut off the current.)


"
Q  What is the normal failure mode of SSRs and why?

A   There are 2 failure modes; failed in the open state and failed in the closed state.  Closed failures are the more common failure mode and this form of failure most often occurs due to overheating of the SSR which leads to an internal melting of components which end up as a closed circuit.  The open failure is most often caused by a separation of solder joints due to extreme temperature changes over the life of the SSR.
"
http://www.hbcontrols.com/ssr-controller-assemblies-technical.asp


Adam

Yes - sorry, I meant typically they fail in the closed state - that is the element will now stay on. This is one of the mains reason that you use a mechanical relay / contactor. Also, SSRs will leak current when not in a failed state and you need to ensure there is no power going to the elements when cleaning - again the mechanical relays are important here as well for safety. There is a good description here: http://www.theelectricbrewery.com/control-panel-part-2?page=13

Go half way down to the How it works section for a good description.

[Ozbrewer]

Advice: Do NOT, NOT bother with a PID controller for your boil kettle- a HUGE complication and increase in cost for NOTHING. You want dial-based PWM control for the boil kettle; don't use a rheostat or you'll just overheat things and burn them out.

Thanks for your response Adam. However, it still doesn't change that a PID controller for you boil kettle does add functionality and can have a purpose.

- Set an alarm and temp target prior to boil to ensure that no boil overs happen. With your solution you have to watch it constantly, or be back and forth the whole time. I reckon that wastes more time than pressing a few buttons.
- Set an alarm and temp for wort cooling when re-circulation. Your PWM solution can't do that.

Honestly, objectively look at just how long and complicated your description is (and it is simplified vs. what you actually have to do; you have to hold down buttons every time you switch between auto and manual mode, then hold other buttons to change the % output or temp, remember which buttons to push when, then wait for the timeout value so the PID actually starts doing what you just told it  to do, etc...).  You have a $60 piece of equipment that can do integral and differential calculus in a boil kettle that just needs "more heat" or "less heat".

Is a PWM more simple in controlling heat to the element and the boil process - Yes. However, the PID doesn't add a massive amount of complexity. Most settings once programmed remain in place the next time the system is used, such as the 80% Manual boil rate. It's simple click of the A/M button on the pid. Not much time or effort to set the temps.

Do I need just more heat or less heat - in essence that is correct. But I also want visibility of what is going on, especially when coming up to the boil and when recirculating for cooling purposes. The PWM won't do that for you.

Or waste your life fidgeting with your brewery hardware instead of making beer.

Actually, one of the reasons I went with the electric brewery clone is because it allows good interaction with the brewing process. I guess I could have gone down the Arduino path and automated fully, but it's not what I want. Realistically, it's not that much fidgeting with the hardware - a few buttons and switch - better control, better consistency, better repeat-ability. IMHO and quite a few others using such a system it seems.

With PWM:

• You don't have to recalibrate PID controllers so they accurately read heat
• You don't have to worry about temperature probes including cleaning, them breaking, resoldering cords, etc..
• You don't have to worry about which buttons to push when to change temp or switch between modes; or which esoteric setting you need to modify when it refuses to switch between automatic and manual modes (yes, that's a thing; yes, it's annoying)
• You don't have to hold a button for 3 seconds to enable a mode that enables you to drop the temperature while hot break is spewing everywhere making a huge mess of your brewing area
• You don't have to spend 60 quid and precious space in your control panel when a simple 2 quid pwm dial will work

The whole point of the PID on the BK will help better prevent a boil over. As to the other points - you don't recalibrate PIDs every time you brew, most do it the once and check on occasion. Switching between manual and auto is by pressing a button on the front of the PID, no more difficult in turning a dial really. You don't have to hold a button for 3 seconds, just press the down button and it will drop the temp and stop the boil, maybe marginally slower than turning a dial - on my system i have safety reset switch for the pids that will kill the boil straight away, or I simple turn the element switch to off and leave the pid in run mode - which is just as quick if not quicker than turning a dial. As for space on the panel - well you size the panel for what you want to do and what you want on it - so really not an issue.

I've bought a lot of "high-end" brewing equipment in the last year and a number of those items made brewing harder, not easier.  IMO, a PID controller, rtd style connector temp probes, tri clamp fittings, a plate chiller, and a shiny flat-bottomed boil kettle are all in that category. -They're "cool", but they introduce more problems than they solve.

Like what problems do they introduce? Each to their own on these I think. PIDs and RTD connectors work well. TriClamp fittings and plate chillers versus other option have been debated ad nausea on all the brewing forums and people will choose what they want for their own reasons - myself, I have QD like in the EB site and a counterflow chiller rather than a plate chiller.

However, overall if they system is well designed and put together you will be able to have better control over the brewing process. 

I'm now moving to v2.0 of my stainless "dream system" and my upgrades include PWM dial-controlled boil (vs pid), removing triclamps and swapping them out for quick disconnects (camlock style in my case), counter flow chiller, and a keggle-based whirlpool kettle.  I used to think that these were "downgrades", but they're not; they work better and require less effort to use and less maintenance, so they're upgrades.

Excellent - do what makes you happy and will work for you. Sounds like some good changes there for you.

My 2 bucket brewery in Dublin (Mashtun: insulated bucket with mesh screen attached to a ball valve; Boil+HLT: plastic bucket with 2 Charlie Shiels kettle elements / computer power cords) was the single easiest-to-use brewery I'll probably ever own... I'm afraid it's all downhill from there, no matter how much money I spend and how many tweaks I make. (although I transferred WAY too much trub to my fermenter with that brewery and always had burny fusols because of it.)

Yep, my old system was easy to use. But it was also very painful in being consistent. The EB clone I'm building will solve all the problems I have had brewing and I personally don't see any downside to it - maybe more things to clean and store - but a minor inconvenience if even.