Dumb aircon - smart hack?

Hello SmartThings people, i’m hoping someone could help me with a home automation aircon hack.

As part of my home automation project i’m trying to “smartify” my old dumb ducted aircon. Want to be able to at least on/off control it via Alexa or a phone app. I’m actually not invested in the SmartTHings ecosystem atm, but do have some z-wave devices and a hub, and an alexa.

P.s. im in Sydney, Australia. We have annoying non-standard aircons here.

The aircon is a 10yr old Temperzone ducted multi-zone system which has a proprietary interface (no popular smart thermostats are compatible, i’ve checked), and also doesnt come with an IR remote. The only way to control it is via a physical wall panel (and this sends signals to a control box that’s in the roof void).

I was hoping to achieve some simple on/off control via some home-automation switch/device for this system, preferably with voice control.

The wall panel has a momentary-press button for on, and another one for off.

Would there be some Alexa/z-wave enabled device that would allow me to manipulate these on/off signals? I dont mind doing some wiring/hacking, etc.
Pictures of wall panel are here:

The on/off buttons work with the contacts labelled SW1 on/off.
Not sure how the signal is sent, i imagine its some type of 12v pulse? A fair bit of pressure needs to be applied to the rubber buttons for the press to register. Can i get some remote-controlled device to send this pulse if i wire it to the switch contacts?

Any ideas? :slight_smile:

thank you!

Ok, so if I were you, I take an Arduino+IR receiver and the associated IR stack you can find on the net, and reverse engineer the IR protocol. Hopefully you are not facing a tricky IR protocol like I had once with a Mitsubishi AC I never got decoded since the sequence was kind of encrypted (so that they could sell their wireless wifi module :wink: ).
Then once you have all the commands, the other way around: the Arduino+wifi or RJ45 + IR emitter LED to send IR sequence a http socket is listening from a DTH you create.

You can base on my implementation for a BT air-purifier. Forget the Pi side and replace it by the Arduino. The DTH itself would be very common. I suggest you to go with json over http between your DTH to the Arduino so that you don’t have too complex things to manage.

My code at: https://github.com/philippeportesppo/Honeywell_HPA250B_SmartThings

Have fun!

I probably should’ve been more clear. Unfortunately this system doesnt come with any IR capability at all. Its only physical push-buttons on the panel, thats it :frowning:

Ok, that one is on me… end of the week and the day…

So now that’s the moment to dig a bit on the net or to find a friend with an oscilloscope to spy the protocol.
Now good news, remove the IR portion of my post and the rest should still apply to this time an simple HW setup but if this is 12V, an Arduino might suffer… Up to 9V and reasonable current, that would still make the trick.
Let’s check what is this HAN-L52. Maybe some guys already reverse engineered it.

Look at that:

There seems to be an interesting connector on the partB (please take care with this one as there is 240V coming in, so no jokes…). On this part B, there is a DDC connector that might be maybe good to hack.

The user manual says:

So now the question is what is the protocol used there…

HW wise, http://www.temperzone.biz/SiteAssets/Public/3867/HAN-L6_Support_Info_0306.pdf

Seems to give some hints:

You might now have enough to proto something as I believe DDC and BMS should have some common implementation, you might even find a z-wave remote in the end and all this search will conclude by: well you just have to buy a xxx DDC/BMS z-wave remote… for few bucks :wink:

Nice find, thanks! Temperzone support didn’t mention anything about this.
Certainly some interesting clues there but I’m not sure if I’d be able to do much with that without a detailed guide. Not a hw guy, and a crappy coder unless there’s good samples. I’ll see what Google turns up regarding DDC/BMS


There’s a simple no wiring solution for this, but it’s probably way more money than you want to spend.

There’s a Korean company, Naran, that makes tiny microbots which are essentially a robot finger. They just push a button. And they have their own Wi-Fi bridge which has its own IFTTT channel. So you pop one of the microbots on the on button and one of the micro bots on the off button and there you have it. :sunglasses: Both SmartThings and Alexa compatibility, no wiring required.

I myself am quadriparetic, so I have a couple of these around the house, and they work fine, they’re just expensive. In US dollars, $89 for the bridge and $49 each for each microbot.

I realize that’s probably more than you want to spend, but I did just want to mention it. They just come out with a second generation push micro but which has somewhat stronger gears and an IBeacon feature, so you can find a first generation on clearance at some vendors. The first generation is the one that I have, although I would recommend that most people get the second if the price isn’t that much higher just because it does have more features.

Reviews are all over the place because the initial app was terrible, but they did fix that in January or February 2017.

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Well, this is certainly out-of-the-box thinking :slight_smile:
That could really do the trick for me. More expensive than other methods, but perhaps not by far (after ive bought a Pi and a relay, etc). Will consider this option, thanks!

My on/off buttons are actually pretty stiff, need a good solid push as they’re rubber and need to compress 1st before the push is registered. Do you think these push-robots would be able to handle it?

I’m using one of them on a blender button that has to be pushed pretty hard (harder than I can press it, which is why I use the microbot to begin with). :sunglasses:

It’s spec’d at:

1.6 kgf torque to push any buttons

So if you put a weight of 1 1/2 kg on the button, would that depress it?

It has the advantage that you don’t void the warranty on the other device, and the buttons can be easily removed again later if you want. So it does solve some retrofit cases which can be complicated to solve otherwise. :sunglasses:

1.5kg would most likely do it, they’re not THAT stiff.
Thanks v much - its certainly an options im going to weigh up

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If you’re interested in the microbots, I would buy them from someplace with a good returns policy just in case they don’t work for you. I got mine from Amazon. :sunglasses:

What i ended up going with as a good mix of easy/cost-effective is to order a dry-contact z-wave relay module which i’ll use to “short” the 2 contacts which control the on/off action behind the on/off button.

This will already integrate into my home automation ecosystem (already running a z-wave hub) and would be pretty easy to wire up. I wont be able to control zones or temperature, but simple on/off via voice is a pretty good start.
Could add one of the robots to toggle zones for me at a later date

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