Simple PID setup/how-to

[Waffty]

Looking at the picture, it looks like you are 'switching' on the neutral wire? If this is the case then you need to change this, to switch on the live wire I.e it's best practice to switch on the live wire (or in an ideal world both live and neutral).

[subfaction]

Thanks for the response, so to clarify should I switch the wires going into 9 & 10 over?

[Waffty]

Thanks for the response, so to clarify should I switch the wires going into 9 & 10 over?

From what I can see, you're currently switching the neutral feed (blue wire), which will work, or be it, even when the circuit is off, the live (brown wire) will still be live, which is a little risky ie when your ssd is off, you'll still technically have a live feed in circuit.

So, if you swap the leads over and have the brown wire going too and coming out of your ssd then, then when the ssd turns off the power, you won't have a live feed too your element (load).

To be honest, it's one of those I.e your config will/would work and provided you were aware of the config, you'd live a long happy life, however there is a 'better way' that takes the knowledge/guess work away and that's to switch on the live (brown wire).

In an ideal world, we'd/you'd be swithing on two poles ie both the live and the neutral, as that would rule out 99.99999% of the risks associated with mains switching.

[Waffty]

Owwwwww and if you're using a metal case to house your PID then make sure you have suitable earth point (in said case).

In addition all metal 'containers' exposed too mains electricity, should also have a suitable earth connection and finally, if your mains distribution board/box (fuse box) doesn't have a RCD, then do yourself a favour and get a plug in jobbie, as it may well save your life.

[subfaction]

Thanks Waffy, I really appreciate the reply

Does this look better:



I'm using a plastic box, and my consumer unit has an RCD

Any idea if my plan of running a pc fan off the ssr pins 8 & 9 would work?

thanks

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[themadhippy]

So, if you swap the leads over and have the brown wire going too and coming out of your ssd then, then when the ssd turns off the power, you won't have a live feed too your element (

with an ssr off theirs still a small bleed through even if the control side is off,its not enough to power your element,but its enough to make you say bad words

In addition all metal 'containers' exposed too mains electricity, should also have a suitable earth connection

realy? so those 4 tins of extract ive got sitting in front of a double socket need bonding

Any idea if my plan of running a pc fan off the ssr pins 8 & 9 would work?

depends if the pid can output enough current,also remember when the ssr's off the fan will be off.

[subfaction]

Going to be doing this tonight any further advice before I do so?

Thanks
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[subfaction]

All setup now, thanks for all the help guys, so easy now I understand how it all fits together
Love the way you learn so much about diverse tech with this hobby!

To speed up auto tuning I was hoping to start with values that are likely closer, any chance i can get your settings themadhippy?

[Fil]

I can confirm the ssr control voltage is adequate to run both a SSr and a 12v 12cm pc fan

[themadhippy]

To speed up auto tuning I was hoping to start with values that are likely closer, any chance i can get your settings themadhippy

will try and remember after the maddness of the weekend is over

I can confirm the ssr control voltage is adequate to run both a SSr and a 12v 12cm pc fan

the voltage maybe fine,but what about the current consumption?

[subfaction]

I'm going to be setting this all up tonight, but not sure on how best to start the auto-tune, assuming it takes a while I won't be brewing afterwards, but if it's quick then I may as well throw some grain in too.

What's the best procedure for this, fill up boiler to the usual ~34 litres of tap water, turn on recirculation pump, set 66c and run autotune?

Or is there a quicker way of doing things?

[JonA]

PID experts - can I ask, do you need a special temperature probe that is matched to the PID (that ebay kit says it comes with a "K Thermocouple"), and how would I go about mounting a probe in my s/s HLT ? Thanks

[AnthonyUK]

The eBay PID can work with most thermocouples types. It just has be be set in the menu so it works correctly

[subfaction]

I ran the autotune a couple of times on Friday, seemed to take around an hour each time.
It was quite straight forward, the only issue was in calibrating the temp probe, even after an ice slurry calibration it was off a fair few degrees @66c.
This could be down to the recirculation though, i.e. pulling from the bottom where it's cooler, although its pretty close to the element, then the drop as it cools as it travels through the return lines.
Anyway I think I've got it nailed, in the end the two lined up with the right offset... time will tell, just need to find the time to actually brew instead of building the setup!
Thanks again for all the help guys!

[darkonnis]

Its a common misconception, just because something reads 0 in an ice bath and 100 at boiling doesnt mean that the inbetween will be correct. calibrate it for the 60 - 78 temp rangr and it will be more accurate