[OpenTRV-dev] OpenTRV at local ham club

[Gareth Coleman]

Hello everybody, I thought I'd take the chance of chipping in even though I
almost certainly don't fully understand the situation!

Seems like you have two separate requirements, one to turn the heating on
and off by text message, and the other to turn the heating on/off by the
alarm output (indicating occupancy). And by 'off' you mean set the desired
temperature to 5 degrees C, 'on' is set to 19 or so.

We've experimented with using a cheap 3G dongle attached to a raspberry pi
and using free software called gammu to send text messages. The software
also receives text messages and drops them into a folder on the raspberry
pi's filing system. It's pretty straightforward to set up - to make things
easy we bought a known-compatible dongle off ebay for £10. Just make sure
the Pi has a decent power supply so that the surges of current the dongle
needs don't make the Pi brown-out.

>From there you could use any sort of simple text parsing system that is
familiar (python, node.js, bash etc) to work out if the heating system
should be changed to enter frost mode. Personally I'd use node-red because
I think it's really good at allowing non-programmers to understand the
system configuration. You don't want to be called out every time the system
needs tweaking - the end-users need to 'own' the system. However if they
are hams then they might be comfortable on the command line editing code
directly, maybe not.

One of the many great things about node-red is that you get a web interface
out of the box, it looks like the attached image. It would be fine for
slightly technical people, not so great for the general public as you can
easily deploy new code that breaks things.

Interfacing with the alarm might be more trivial or not, depending on how
the alarm works (I've not experimented with such systems). But assuming
it's something accessible such as a relay contact or a simple signalling
voltage with some ability to source current, you can just whack it into the
Pi's gpio pins (maybe use an opto-coupler or buffer to make things more
robust) and take things from there.

Hope that helps

Gareth


On 29 July 2014 10:35, Kevin Wood <EMAIL ADDRESS HIDDEN> wrote:

> Hi Bo,
>
> I'm actually working on something quite similar at the moment for a second
> home that needs frost protection / monitoring remotely, in this case with
> oil fired heating.
>
> My plan is a raspberry pi attached to an AVR which controls the heating
> system.
>
> I'm thinking that the AVR can harvest temperature data from a couple of
> OneWire sensors, run the heating and hot water schedules and control
> relays that activate the heating system as required. It'll also have an
> RFM on the board for later integration with OpenTRV and, if I can reverse
> engineer it, the wireless oil level sensor on the oil tank.
>
> R-Pi can host a web interface or, more likely in the first iteration,
> provide a mechanism to at least SSH into it and check everything remotely.
> Of course it could also do email notifications and SMS would be possible
> either via an internet SMS gateway, or just hang a GSM module off it with
> a cheap pay as you go SIM installed?
>
> Does this premises have internet connectivity?
>
> Kevin
>
> > I was at local ham club last night at looked at their heating
> >
> > So far i "THINK" its all electrical heating as there is no district
> > heating
> > installed, makes things a bit more easy since heat not used will go back
> > to
> > the cylinder :-D
> >
> >
> > Next bit, there is one big room with 4 rads, which means one box should
> > control them all, the box will be central placed. Its mainly old timers
> so
> > the less complicated the better, the rest of the rooms are one rad per
> > room.
> >
> >
> > Mostly @kevin but others might chip in, they have some kind of remote
> > control where they can send a text to turn stuff on and they would like
> to
> > be able to turn on the heat remotely, how could we get to that?
> >
> > the point is that when the house is locked heating should turn off
> > completely or run at 5degree to prevent frost issues. then either by
> > remote
> > command or when house is unlocked it should go to warm mode, there would
> > be
> > no need to sense if its day or night or if people are in the room etc.
> the
> > alarm will output a signal when its on/off
> >
> > any ideas?
> >
> > /bo
> >
> > --
> >
> >                  |||||
> >                @(~Ô^Ô~)@
> > -------------oOo---U---oOo-------------
> > |                                     |
> > |  Bo Herrmannsen                     |
> > |                                     |
> > |                                     |
> > | "blessed are the "cracked",         |
> > |  for its they who let in the light" |
> > |                         Ooo         |
> > |_________________ooO____(   )________|
> >                  (   )    ) /
> >                   \ (    (_/
> >                    \_)
> > _______________________________________________
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> >
>
>
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-- 
------------------------
Gareth Coleman
layer zero labs
l0l.org.uk
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