Can OpenHab on Android control dumb temperature sensors and relays?


What a fantastic piece of software this is. I’m new to OpenHab and home automation.

I’m in the USA and know programming and electronics. My house has two zones of water radiated heat with continuous pipes and gas broiler by weil-mclain Model VHE-5 Series 3 from around 1995.

Could you recommend the cheapest, most stable full solution for this. If no full solution then piecemeal or else diy.

Three temperature sensors wired to three Android devices (or wireless standalone sensors) on second floor that get averaged. Two same temperature sensors on first floor that get averaged. Both floors on separate heat control zones. Ideally these temperature sensors would be dumb and without displays, wired to a wireless Android device. Can openhub be the logic to transmit the temp to the primary Android mobile controller?

All averaging and daily logic controlled wireless by the primary Android mobile controller that’s permanently powered, on second floor.

The primary mobile wirelessly controls two zone relays (or controllers) next to boiler. The relays have no logic nor display. All the logic is by the primary Android mobile. All these use standard open source software and protocol like z-wave or zigbee. Does openhub replace OpenTherm? “OpenTherm controllers and boilers do not in fact always work properly together.” From wikipedia.

Can openhub on Android mobile serve as a daily boiler control and do sensor averaging?

This primary Android controller gets adjusted and monitored from multiple Android mobile and from desktop that’s off at nights. Off course security is critical. As is privacy from data harvesters like Google and Amazon. So local solution that can be securely adjusts and monitored when away from home.

All this bypasses the existing wired thermostats. But in case of wireless outage, the two wired thermostats would override. Is this paragraph possible by openhub? How about all the other paragraphs?

Any direction on hardware, software and installation reading would be helpful.

Hi Doug,

The short answer is, “no”. The openHAB app for Android is really meant to be a user interface, and is not a full-blown OH system. You can get data from the sensors on an Android device and use it to control your OH system, but you can’t easily send commands to the Android device without using something like Tasker. Moreover, I wouldn’t personally trust that many Android devices to run reliably, particularly when connected to your heating system.

However, if you remove all of those Android devices from the equation, you should be able to accomplish what you want to do in some fashion.

I don’t recommend this approach. You’re better off replacing the existing thermostats with openHAB-compatible thermostats, so that all of your control is synchronized in one system. There’s a lot of discussion of thermostats in the community, so I’d encourage you to do a search and see what others are using (keeping regional differences in mind).

As for sensors, there are lots of choices, particularly in Z-Wave and Zigbee. You could easily have as many as you want in your house, and you can use OH to calculate averages and show historical data.

And really, that’s all you need: sensors and new thermostats. By keeping your hardware simple, you remove failure points that will likely cause you headaches, and retain flexibility to modify your system over time.

Hi @dougstout,

Does openhub replace OpenTherm? “OpenTherm controllers and boilers do not in fact always work properly together.” From wikipedia.

No. OpenTherm is a standard protocol thats used mainly for communication between thermostats and boilers, although it is also used for airconditioners, heaters, heat pumps, etc. As long as the devices implement the OpenTherm protocol conform specifications, things should work without any issues. The possibilities are of course limited by the set of commands each device supports.

There are ways to connect openHAB to the OpenTherm message bus, to allow reading and in some cases setting of values like temperatures, pressures, diagnostics, etc. It usually requires a gateway that is connected in between the boiler and thermostat, and some software.

One relatively easy way is using the OpenTherm Gateway module (or this prebuilt one) together with the OpenTherm Gateway binding in openHAB.

Other options are creating your own gateway using something like an Arduino, or get a consumer ready device like this. Depending on which device you use, you will probably need to configure some middleware like a message bus to link it to openHAB.