Pid Control - Sensors (thermocouple)

[Gout]

Hi brewers, very long time no post (been living and working in the uk for 3 yrs - hence no room for a brewery)

Now i am back I want to set up my HERMS with temp control via PID like so many others have. Doing a search i get nothing on PID but looking at many setups/threads and google i see there is so many different sensors in use.

Is one style better than others? are some not safe to have in the hot beer of a mash tun (herms output)?

I have cheap ones for temp (K-thermocouple) were its just the wire with a welded bead - i assume these are not as good? eg some have these placed between your platic tube and the metal output of your herms.

Secondly there is some with a metal sleave and a thread that could be used in the liquid - but i am unsure if this is safe, or are they slow in temp response?

I thought i would ask as i am sure you HERMS and RIMS setup brewers will know more about the options and what works best.

Cheers

different styles are:

 

[schooey]

I use PT100 RTD sensors.Very accurate, easy to find fittings to fit them in, easy to get replavcement bits, and they come with weatherproof heads for the princely sum of $50 odd

 

[Gout]

Hi shooey, thanks for the prompt reply. is the first photo a PT100 RTD as you mention? I only ask because thats an example on ebay where they call it a PT100 RTD

is PT100 a brand / style of sensor or something more technical?
by the way that one is only $14odd posted so i assume the ones you use are of better quality

 

[schooey]

The RTD means that they are a resistance type probe, I think that the PT100 means that they are 100 ohm, but will be happily corrected by a sparkie/instrumantation guru..

The ones I have look like this....and that's not a bad price..

 

[Thirsty Boy]

On a lot of the PIDs I have seen, you get a finer precision out of the RTDs than the thermocouples. Also better accuracy because they have a smaller range.

Most of the pids are accurate over a % of the total range of the sensor - and a lot of the K type thermocouples have a really big range suitable for furnaces etc.

I'm in the process of changing my brewery over from K type thermocouples to the Pt100 rtds and think that they are a better and more accurate option for brewing applications.

 

[schooey]

If you are going to go down the road of the generic PID like a lot of people have, still do a comparison on what you will get for your dollars. There are plenty of cheap crap built PID's out there that will only change a relay, don't have an output channel or an output power sorce to drive an SSR and have pretty shite tolerances and programming variables. Also decide whether you want ramp/soak features etc etc

Save you kicking yourself later on

 

[QldKev]

The sponsors above have a few kits for temp controll, otherwise try someone like Auber Inst. I'm using their Pyrometer setup in my 4wd and no drams at all.

QldKev

 

[Gout]

I was planning to go down the cheap PID controller road - due to cost and my lack of completely understanding the extra benefits of the more complex units. (in fact because i saw the 'cheap ebay units' mentioned so many times i assumed it was easy to select one)

sounds like a PT100 sensor is the go over K-type thermocouples.

for the HLT i would hope a basic unit could control this as i basically want to set a temp and it take care of that while i fluff about brewing. I was using a pic micro with some basic code, a SSR and electric heating. Biggest issue was temp difference due to a lack of agitation. Once this is resolved i hope a PID would just ramp up and stops at the given temp and maintains it until i am ready to sparge / mash in etc

The Herms i understand will require far more switching or controlling of the temps, maybe this will require something more advanced than the $40 ebay versions or as QldKev suggests (they seem to have some handy sensors there)

guess i have some more reading to do and acronym understanding.

cheers

 

[Thirsty Boy]

the cheap e-bay ones are working for me - just need to make sure the specs meet your needs.

K type will do the job and most of the ebay pids come with one - you will need relays too, I use mechanical ones for my own nefarious reasons, most people are using SSRs which you can usually get from the place that sells you your PID.

That said - people are running perfectly effective HERMS systems with stock standard on/off controllers.. it all depends on how you set it up.

 

[Gout]

Hi brewers, I have spent some time looking about and once i found a sensor RTD100 2" stainless and water tight i decided to buy the PID from them also which they tell me fuzzy logic enhanced PID are the better option (however the cheaper would also work).

I know it may be a slightly more advanced than needed pid system however there was no help via the ebay/china supplys.

Now the fun, tuning and dramas will begin.


I have some old hops and grain that i cant bring myself to throw out so these will be the test brews after some water only tests.
I did have my home made pic controlled dodgy HERMs working before i left so i hope it comes together.

I also burnt my last week pay on a water pump (big one - $140 at bunnings + $50 on fittings and the hoses grrrr) to use our large rain water storage tank to re-use it for cooling the wort (rain water for the plants etc not drinking) -

Hopefully i soon have a brewery again. If this pid works i will make a on/off or cheap PID for the HLT

Next - and important for the HLT measurement is a stirrer ...... but thats for another thread


I would like to thank everyone for there comments that have really helped me move forward with the PID's / sensors

 

[Gout]

Today my packet of joy turn to pain arrived in the mail. I now have a PID, stainless sensor and SSR. - must be a real brewer now

so the joy soon turned to pain when i got the sensor and thought ok this goes into the herms coil.... ummmm hmmmm how?

I was thinking to add a T peice and have the sensor run from T to into the pipe and the outlet at right angle.
Solder a nut to suit the 2” probe, 1/4 NPT Thread. I am used to working with metric so all my taps, nuts etc are metric

Has anyone else overcome this challange?

I might visit bunnings and see if anything suits - but i dont fancy my luck

 

[paulwolf350]

Today my packet of joy turn to pain arrived in the mail. I now have a PID, stainless sensor and SSR. - must be a real brewer now

so the joy soon turned to pain when i got the sensor and thought ok this goes into the herms coil.... ummmm hmmmm how?

I was thinking to add a T peice and have the sensor run from T to into the pipe and the outlet at right angle.
Solder a nut to suit the 2 probe, 1/4 NPT Thread. I am used to working with metric so all my taps, nuts etc are metric

Has anyone else overcome this challange?

I might visit bunnings and see if anything suits - but i dont fancy my luck

Dont think you need to splice into your herms coil, just put the probe in your mash tun, all you need to do is weld or solder a 1/4 npt thread into the side wall of your mash tun if it is metal, or use a bulkhead fitting if it is plastic

Paul

 

[AndrewQLD]

I have a T on the exit of my herms with the thermocouple. I prefer this to having the probe on the exit into the mash as I know exactly what temp my wort is at as it passes through the herms, Screwtop put me onto this and I think my consistency has improved because of it (thanks Screwy).

 

[Gout]

my mash is metal however from what i read the outlet of herms is the ideal spot

that said my herms is un-used and just a coil and needs a pipe added so the T is not a problem, seems like i need to sort out a 1/4 npt to add it into the system

 

[paulwolf350]

I have a T on the exit of my herms with the thermocouple. I prefer this to having the probe on the exit into the mash as I know exactly what temp my wort is at as it passes through the herms, Screwtop put me onto this and I think my consistency has improved because of it (thanks Screwy).

Lucky my herms is not up and running yet then, LOL

Paul

 

[AndrewQLD]

Lucky my herms is not up and running yet then, LOL

Paul

I'll get a pic tomorrow and post it up.

 

[Gout]

thanks andrew this may help and inspire

 

[schooey]

This is mine, gout, but yours will be different because of the typ of sensor you have...





Like others, I have the PID that controls the solenoid valves to change over from Heat to Bypass located at the exit of the Herms coil. That probe actually goes right through the tee into the turbulent stream to avoid getting a false read from a dead end.

 

[Gout]

apart from the setup how did you screw it in - are these fittings avalible and easy to buy?

sorry for the basic questions

 

[schooey]

Those probes don't screw in. They slide through a ferrule and you tighten the nut, a bit like a compression fitting.