Brewpi Fermenting Fridge

[tim_n]

Southern Temperature Sensors have thermowells in various lengths and are in the UK. This one is 250mm

HERE

Good stuff - sadly the US ones are slightly cheaper ($12ea) when ordering two with a combined $24 shipping..! About £15 each Madness.

 

[seanmac]

So am I right in saying that the orange fridge setting is the temp you want the fridge to be? and that is causing the oscilaltion?

That oscillation looks pretty crazy, about 20 oscillations a day? with an amplitude of 5oC? PID should be alot more stable than that. If this is not what your after, have you tuned the system at all? Looks like it is near the ultimate gain and period which you could then put in Ziegler-Nichols and get the correct constants?

Maybe im just mis-understanding though cause your latest graph of beer temp looks good!!!

no the orange line is incidental to the process, the green line beer temp is what im controlling.

its set to stable beer temp (19.5c, 21c and then 2c) so the beer stays stable (within 0.05c) and the environment (heating and cooling) changes to keep the beer stable.

im just setting the system up at the moment, literally the first batch through it, so its still learning the setup

Ah nice, thought I was reading it wrong, just looked crazy to me.

Anyway, that looks nice and stable then :

 

[tim_n]

Today my brewpi shield arrived. I'd gone for the slightly cheaper solder it yourself job.

My electronic friends usually redo all the work I do, but one of them said "your soldering is getting better"

Also I turned it on and it worked first time! I'm very impressed. Took a while to work out how the sensors worked, but sorted in very short order. Next I got the web interface working and password protected for when I'm working away from home.

Now just need to run the sensors into the fridge and build a shelf to support the brewing and I'll almost be done!

 

[djcorbetto]

Fancy giving me a little guide to how you set it up? And the way you connected it to the pi and what you installed? I've got one but it's confused me too much

 

[tim_n]

Depends what bit you want help with! Is it the software or the hardware?

The only bit where I had to go a bit off piste from the instructions on brewpi.com was registering the sensors and enabling password protection. Everything else went pretty smoothly!

 

[djcorbetto]

It's the software part for me

 

[tim_n]

It's the software part for me

A bit easier then.

How far did you get? Have you setup the pi? arduino? got the interface up and running?

I've just finished mine. I thought we'd be done by midday having started at 10:40. No such luck!

 

[tim_n]

Today I did the hardware modification and brewed some beer at the same time.

(http://www.albumonline.net/display.php?id=daaec33c - fridge and pi pic)

I started by taking the top off the fridge so I could see if I could easily make a hole in it without actually destroying the cooling lines. After a fair bit of scraping I discovered the top of the fridge and no cooling lines. Because the top of the fridge was raised off the foam, I was able to mount XLR chassis mounts on the side of the fridge. I'll still need to fill the holes where the sensor cables went, but it's no big problem.

Having done this we attached the heating element. I've used an old brew belt which I was given 10 years ago and have used twice. I stripped off the plug, soldered the ends of this and the wires we'd run into the fridge together and used cable shrink wrap to make it watertight as possible.

The fridge itself, I just snipped the wires from the compressor and control it direct. This means I loose the light but I'm not that bothered. The fridge plug became the plug for the SSRs.

What was a bit odd was the plug socket had a 13A fuse, yet the fridge only used about 0.6A. Seems a bit silly to me.

On each of the hot lines we put an inline fuse.

SSRs were rated at 10A. Though as the circuit will only be drawing a tiny amount, I doubt they'll ever be needed.

We mounted the SSRs in a plastic project box and connected up to the brewpi.

Had a small hardware issue with connecting the sensors. Red = 5v/Live obviously. Thought the blue was the neutral and the black was the control/sensor cable. Turns out I was very much wrong. Was infact the other way round. No problem, switched the cables round and all worked. Shame it took over two hours to work that out.

Once the sensors were working it was possible to run the heating/cooling elements and test. I used the fridge temperature to control, setting to 9 to start with then putting it back up to the outside ambient temp of about 13. I'm going to leave it running overnight and see if burns down the garage. Then I'm going to use my bottle bucked and thermowell to test the temperature control with a beer profile (eg 20'C for 3 days, 16 for 4, 20'C for 3 then crash cool)

Brewpi screen of first test.

http://www.albumonline.net/display.php?id=3f6ae954

 

[jkp]

Can the brewpi take a gravity reading?

Just thinking that if you are going to control the temp remotely you might want to know this before performing a cold crash for example, or just to monitor the fermentation progress.

 

[tim_n]

Can the brewpi take a gravity reading?

Just thinking that if you are going to control the temp remotely you might want to know this before performing a cold crash for example, or just to monitor the fermentation progress.

There's no reason that it can't, but you'd need a sensor capable of taking a hydrometer reading.

I've never had a fermentation that's gone on for more than two weeks, so I'd assume it was done by then. If I change what I'm brewing to something where I would expect it to take longer than two weeks, then I'll adjust the beer profile.

 

[naturals]

Can the brewpi take a gravity reading?

Just thinking that if you are going to control the temp remotely you might want to know this before performing a cold crash for example, or just to monitor the fermentation progress.

There's no reason that it can't, but you'd need a sensor capable of taking a hydrometer reading.

I'd absolutely love this feature! I did a bit of research but couldn't find anyone who had done it so far.

 

[tim_n]

Can the brewpi take a gravity reading?

Just thinking that if you are going to control the temp remotely you might want to know this before performing a cold crash for example, or just to monitor the fermentation progress.

There's no reason that it can't, but you'd need a sensor capable of taking a hydrometer reading.

I'd absolutely love this feature! I did a bit of research but couldn't find anyone who had done it so far.

Quite a lot involved I think. The guy who runs brew pi has been looking into it though. seen talking of measuring by weight, lasers and all sorts. At its simplest maybe a webcam pointing at a hydrometer left in your brew would suffice.