How to: Raspberry Pi HLT/Boiler Controller

[Robbo100]

I think it should be a number and not letters.

I think it may be a row 0 vs row 1 issue.

 

[thear25]

Hi Guys, I've been glued to this thread for the last month or so and am finally in a position to start building and programming, which nicely coincides with filling my last FV on the weekend so there is a lovely window before the next brewday.

 

[Robbo100]

Excellent.

Pacman has got his working, but for some reason has been banned from the forum.

 

[thear25]

Well that's not very good at all. Have many others managed to follow through the "how to" and get it working?

 

[Robbo100]

Yes, Pakman has, and seems to love it!

 

[thear25]

How did you guys get familiar with the raspberry pi in the first place, I'm getting everything in place now but looking at options of using some of the setup to monitor the beer when its not brewday!

 

[Robbo100]

I self taught.

Basically, I had a project in mind, and then went out to make it happen. Lots of research and mistakes!

 

[brewman38]

Brilliant im in process of setting up and this is the best hopefully can follow it and build it brill

 

[yoyomet]

As I have 2.7Kw kettle elements I need over 10A. I've looked at the Beefcake Relay Control Kit referenced in 2.2 of the instructions but think a solid state relay such as the FOTEK Solid State Relay SSR-25 DA would be simpler - http://www.ebay.co.uk/itm/Solid-Sta...onents_Supplies_ET&hash=item3ce45f8c2bhttp://

The question is, will the circuit in this design switch the SSR? The specs of the SSR say the Min. ON > 2.4V and OFF < 1.0V with a trigger Current 7.5mA / 12V.

Thanks in advance for help on this.

 

[hulmea]

I wish I had seen these solid state relays before. I had to use a 2n7000 with old fashioned relays. These look a great idea.

The only thing I would look out for is on start the PI can have a voltage on the pin at around 1V. I used a 10 K pull down resistor on my MOSFET to ensure it is not triggered.

You may have to do the same with this relay to stop it turning on by accident. Once booted if will be less than 1V so it shoud be fine. When the pin is up it will be around 3.3v so that should be plenty to run this. let us know how you get on as i really fancy these.

Cheers

Andy

 

[yoyomet]

Andy - thank you for the response. I'll be getting parts together and trying these relays over the next few weeks along with finishing the brewery build. I'll get back once I've go something to report (or another question!).

Martin.

 

[Fil]

fwiw the 25a fortek SSR's available on ebay for a quid or 2 need 3-32vdc to drive them, and an arduino with a 5v hi on its gpio pins is ample to drive one. Just dont forget the heatsink and be aware even when off these can bleed a load current so further isolate anything fed by them when you want it OFF.

Dont leave your elements dry and plugged into SSR control fed by a live current, they will bleed and your elements will start to heat up, not at a massive rate and will stay just hot to the touch for minutes but could if left unattended be a risk.

 

[yoyomet]

Fil - thanks for the heads up about the advice on the bleed - well worth knowing! You said don't forget the 'heatsink'. Do the SSRs get that hot? Should I stick a heatsink on each one?

 

[Fil]

Fil - thanks for the heads up about the advice on the bleed - well worth knowing! You said don't forget the 'heatsink'. Do the SSRs get that hot? Should I stick a heatsink on each one?

I am using the standard 25a fortek ssrs found at bargain basement prices on ebay, under pid control heating my hlt to a sparge temp of 85C with 2 x 1.5kw elements powered through a single SSR i measured the temperature of the 1st fin on the heatsink under load with an accurate tip mounted probe at circa 60C

you can just make out the probe (long silver thing) wedged in the heatsink..

 

[yoyomet]

I am using the standard 25a fortek ssrs found at bargain basement prices on ebay, under pid control heating my hlt to a sparge temp of 85C with 2 x 1.5kw elements powered through a single SSR i measured the temperature of the 1st fin on the heatsink under load with an accurate tip mounted probe at circa 60C.

you can just make out the probe (long silver thing) wedged in the heatsink..

Thanks Fil - My load on each one will be 2.7Kw so I'll incorporate a couple of heat sinks

 

[Robbo100]

Hi all,

Just to let you know, that I won't be supporting my Boiler/HLT/Fridge controller on this site anymore. If you have any questions, then I will be able to answer them on Pinventor.

I hope the mods don't mind me linking to this other site - it is not a brewing site, so shouldn't be a problem.

Cheers :thumb:

Robbo100

 

[Robbo100]

If you ever wanted to make a Raspberry Pi HLT/Boiler Controller, but didn't want to bother with sourcing all the components and wiring it all together, there is a new Raspberry Pi Add-On Board (called the Pi&Bash>_) which will do the job almost out of the box.

All you would need to do is to connect your relays to the digital outputs, and add your thermometer chips to the GPIO4 output (or use the supplied analogue thermometers), and you are in business!

The code would need tweaking, but it would be a pretty easy job to do. I might get one and give it a try!

Details of the Pi&Bash>_ are here