Pot for HERMs

[jim80]

MacKiwi, is your code for the on/off as simple as be, in other words something like

if (measuredTemp >= desiredTemp)
{
turnHeatOff()
}else{
turnHeatOn()
}

or do you have something that either smooths out or ignores noise in order to prevent rapid on/off switches close to the desired temperature? I think the term might be something like "hysteresis", but I've forgotten most of my engineering education so I might be wrong about that.

 

[MacKiwi]

Hi Jim - that is exactly what it is. I put that in just to get things running, and it appears to work quite well.

Hysteresis is the right term, but I've not observed any in the system. There is some inertia in the system which prevents any oscillations that are faster than the sample time, so hysteresis doesn't seem to be a problem.

 

[jim80]

Ok, thanks again!
I won't have to stretch my brain too far to try that one then :)
I'm using the dallas 1 wire temp sensors, I've noticed they can show a bit of dithering about so I thought I might average out the last however many readings.
I think the sample period is likely to be a few times a second from memory - I'm using the 3 wire config, which might be a bit faster, although I could of course slow down the effective period in software.
Which sensor are you using (excuse me if it was earlier in the thread and I missed it) ?

Edited to add : Scratch that, you're you using the same, now that I read the thread properly!

 

[jim80]

One more thing (Sorry to keep on with the questions!).
Where did you get that A/C LED volt/amp meter?
I'm pretty sure I don't need one, but I still want one!

 

[MacKiwi]

Hi Jim, yep, same sensor, in 3-wire mode. They are pretty ubiquitous. I'm sampling once per second at maximum resolution (to 1/16th of a degree), which is about as fast as they will go.

I don't think there is any harm in averageing the samples. But I've not seen the need for it myself.

The volt/ammeter is pointless bling, but nice to have. I do have a habit of not plugging in my kettle leads, so the meter makes it obvious when there is no current going through the circuit. It is one of those ebay-shipped-from-Hong-Kong things, and I got it here...

http://www.ebay.co.uk/itm/Blue-Digital- ... OC:GB:3160

 

[jim80]

>The volt/ammeter is pointless bling

But it's not much more than a pint of youngs in one of my locals ( Only just short of five quid for one of those !!! - it's not even very nice beer in my opinion! I only go there because it's a nice pub and I like the barmaid )

 

[Northern Brewer]

I'd like to hear an update from NB about his heat exchanger. I've been thinking about it recently and wishing I could just buy one like that all pre-made. It looks really nice, and I imagine that it's a fairly precise piece of equipment. I don't know if he will post anything though, I don't think he hangs around the forum much anymore.

I agree - his bunker brewery thread inspired me to have a go myself. Lots of great stuff in there

Thanks guys! Much appreciated :hat: I am still hanging around and brewing/reading/posting occasionally but I kind of got side tracked on other projects, some brewing related and with kids/work I'm having difficulty squeezing it all in. I've had an ongoing project for 8 years with an old Fordson Super dexta tractor which I need to use now but is in bits so I've started that again and that triggered me to buys some more tools such as a milling machine and a mechanical hacksaw which both needed repairing, which made me buy a welder and join another forum called the MIG welding forum. All these tools have brewing applications, I do intend to make some more shiny bits soon, starting with a hop filter design i have had in my head for a while. I'm using Alemans' copper pipe design which works brilliantly and uses everyday materials but can be a faff to clean so thinking of making a version in stainless with less fixings now I have the tools.

This weekend one of the guys from the MIG forum came over with 2 of his mates who are thinking of brewing beer for a pub they are buying so I had a brew day with them so they could see what's involved. I think it went down very well. I didn't take any pictures, I was knackered having spent the previous night awake looking after the eldest daughter who threw up on the landing at 2 in the morning :sick:

I'm also automating my underfloor heating controls with a raspbery PI and a couple of Arduino microcontrollers and a bunch of relays, once I have sorted this out I can see a brewing application for similar technology I've seen others post about Arduino's and brewing so will check that out at some point.

Cheers
Andy

 

[PD]

welcome back...your non presence has been of concern....

Keep us informed of your builds as has been said they are appreciated and have spurred other folks on....and if your selling your hermes pot can I be first in line

 

[Northern Brewer]

welcome back...your non presence has been of concern....

Keep us informed of your builds as has been said they are appreciated and have spurred other folks on....and if your selling your hermes pot can I be first in line

Will do, probably worth mentioning that most of my ideas were triggered by other posters before me. I see that there's a few on here with microcontroller skills that I may be in need of, I haven't programmed in anger for a few years so a bit rusty, just waiting for my RF stuff to link my arduinos to the raspberry pi.

Next serious bit of shiny will be perastaltic pumps, I'm really bored with priming pumps, even with bleed valves. I've tried solar and toton, both crap, I haven't tried march may but they are similar technology so don't expect them to be any different. I bought a small perastaltic pump seconh hand for a tenner to play with before moving on to make my own.

Cheers
Andy

 

[Loetz]

I do intend to make some more shiny bits soon, starting with a hop filter design i have had in my head for a while. I'm using Alemans' copper pipe design which works brilliantly and uses everyday materials but can be a faff to clean so thinking of making a version in stainless with less fixings now I have the tools.

Forget all of those other distractions and start building heat exchangers and hop filters and sell them on the internet.

 

[PD]

:thumb: pushes in front of Loetz....

 

[MacKiwi]

Good to hear from you NB - tractors, milling machines, MIG welders. Sounds like you're having fun

As chance would have it, I'm also automating my underfloor heater with some Atmel micros and and a Raspberry Pi (I'm an electronics engineer, so this is a little closer to my core competance than brewing), so I'd be great to hear how you get on...

 

[Northern Brewer]

PD and Loetz, thanks guys. if I get pushed out of my day job I'll think about it

Cheers MacKiwi. I may be picking your brains, I'll have a good go myself first as its the best way to learn but I have some serious gaps in my knowledge. I'm used to C and Perl, Python seems easy enough and there seems to be plenty of libraries around to simplify things. I've bought some one wire thermometers, a couple of 433Mhz RF interfaces, an RPI, an Arduino Due, a 16 channel 12v relay board and I have some spare underfloor heating valve actuators. I've also got a few breadboard etc. I've got 3 different underfloor heating manifold locations so if it works I'll have 3 arduinos/relay boards. I best stop before I completely hijack the thread :whistle:

Cheers
Andy